Fairing for stepped hull boat with cambered planing surfaces

Abstract

The present invention relates to stepped hull boats featuring cambered planing surfaces and is intended to reduce hydrodynamic resistance and improve efficiency of such boats in displacement and transitional modes by means of specifically shaped retractable fairings not compromising the operation of boats in the main high-speed planing mode, which is achieved by equating the angles of inclination of tangents to contours of the cambered surface and the fairing in vertical longitudinal sections at the trailing edge of the cambered surface and specific progression of the tangents along said contours, which results in the formation of a bulge in the front part of the fairing, which bulge, in the displacement and transitional modes of operation, protrudes downwards below the trailing edge in projection onto the transverse plane, whereas in the planing mode, the bulge, like the entire fairing, is located above said trailing edge.

Description

RELATED U.S. APPLICATION DATA

[0001] Patent application Ser. No. 18 / 759,866, filing date: Jun. 29, 2024

[0002] patent application Ser. No. 19 / 009,993, filing date: Jan. 4, 2025

[0003] Int. Cl. . . . B63B 1 / 00; B63B 1 / 08; B63B 2001 / 045; B63B 2001 / 145; B63B 2007 / 003

[0004] U.S. Cl . . . 114 / 271; 114 / 284FIELD OF CLASSIFICATION SEARCH

[0005] CPC . . . B63B 1 / 00; B63B 1 / 08; B63B 2001 / 045; B63B 2001 / 145; B63B 2007 / 003REFERENCES CITEDU.S. Patent Documents2,985,130May 1961Jacobs et al.3,019,755February 1962Diamond3,763,810October 1973Payne3,614,032October 1971Purcell4,519,336May 1985Mason5,224,436July 1993Stricker6,042,052March 2000SmithOTHER PUBLICATIONS1. Sighard F. Hoerner, “Fluid-Dynamic Drag”, (1965).2. I. T. Egorov and V. T. Sokolov, “Hydrodynamics of High Speed Vessels”, Sudostroenie, 384 pages, (1965).

[0008] 3. Eugene P. Clement, “The Planing Characteristics of a 15-degree Deadrise Surface with Circular-Arc Camber”, R&D Report 2298, Hydrodynamics Lab., David Taylor Model Basin, Washington D.C., 30 pages, (1966).

[0009] 4. Eugene P. Clement, “How to Design an Efficient Stepped Planing Boat (Dynaplane Boat)”, 65 pages, (2006).FIELD OF THE INVENTION

[0010] The present invention relates to stepped hull planing boats featuring cambered planing surfaces and is intended to improve the efficiency of such boats in low-speed displacement and transitional motion modes by using specifically shaped retractable fairings consistent with cambered planing surfaces, which fairings do not compromise planing mode and ensure high efficiency of boats in a wide range of Froude numbers.BACKGROUND OF THE INVENTION

[0011] Various planing boats, including runabouts, motor yachts, work boats, patrol boats, etc., which are the subject of this invention, are intended to move in their main operating mode at relatively high Froude numbers based on displacement:FrD=V / (g·D1 / 3)1 / 2,where “V” is speed, “g” is acceleration due to gravity, and “D” is displacement.

[0013] This range of relatively high Froude numbers includes FrD from about 1 to 3, called the transitional (or semi-planing) mode, in which hydrodynamic pressures on the bottom of the boat make up a significant proportion of the forces supporting the boat on the water (along with the Archimedean forces) and substantially affect the behavior of the boat, and FrD greater than 3, corresponding to the full planing mode, in which the support of the boat is provided predominantly (by 95% and more, e.g.) by hydrodynamic lift.

[0014] Lower relative speeds (roughly at FrD less than 1) correspond to the displacement mode, in which the boat is kept on the water almost exclusively by Archimedean forces.

[0015] In order to provide efficient, low-drag motion of a planing boat in its primary high-speed planing mode, the flow of water along planing bottom surfaces of the boat must be separated at fairly sharp trailing edges of said bottom surfaces, for which purpose the trailing edges should be arranged substantially transversely (i.e., should be normal or arranged at some substantially large angle to the center plane of the boat) and must be exposed to atmospheric air by means of a step formed by surfaces extending substantially vertically from the trailing edges, which requirement presupposes a stepped configuration of the bottom portion of boat's hull with substantially vertical and transversely arranged transom and additional steps behind any other planing surface in the case the boat has more than one of them like in “stepped hulls”, which reduce hydrodynamic resistance and improve the efficiency of planing boats compared to conventional boats with only one transom step and flat “stepless” bottoms.

[0016] Another effective way to reduce hydrodynamic resistance and improve the efficiency of the boat when planing is to give the planing surfaces a special concave (cambered) profile in vertical substantially longitudinal sections corresponding the direction of the flow along the bottom, while a combination of such cambered planing surfaces with stepped bottom designs ensures the greatest increase in efficiency of planing boats.

[0017] Accordingly, the most hydrodynamically advanced stepped hull boats with cambered planing surfaces is the subject of this invention, including, in particular, a hydrodynamic configuration with successively arranged lengthwise bottom and transom steps, both of which are provided with cambered planing surfaces (that is, the trailing edges of the cambered planing surfaces represent the edges of bottom and transom steps).

[0018] Considering operation of planing boats it should be noted that along with the inevitable sailing in displacement mode during acceleration before taking off on plane, in practical operation, planing boats, including planing motor yachts, are often operated in displacement mode of motion for a substantial portion of their period of use (even more than in the high-speed planing mode, intended as their principal mode of operation).

[0019] This is, in particular, due to the fact that, as a rule, because of a significant reduction in the power required to propel the boat, fuel consumption per mile in displacement mode and even sometimes partially in transitional mode is less than in planing mode, which provides a significantly greater cruising range (at a much lower speed, of course).

[0020] However, the configuration of a typical planing boat with sharp trailing edges and steps (there is at least one step, which is the transom) is far from optimal for the displacement mode of motion, while giving it optimal for low Froude numbers hull shape-without steps and with smoothly curved bottom contours-could significantly reduce resistance, power and fuel consumption and, accordingly, increase efficiency and cruising range.

[0021] On the other hand, smoothly curved streamlined bottom formations are unacceptable regarding the hydrodynamic efficiency of a planing boat in its main high-speed mode.

[0022] This dilemma (i.e., smoothly curved bottom formations required for low speed motion and angular stepped bottom formations with exposed sharp trailing edges required for the high-speed planing mode) can be resolved by equipping the stern and any other step on the boat bottom with a retractable fairing arranged behind the trailing edges of every step, made conformable to the trailing edges and abutting them in its forward part, and provided with a shape transforming, along the length of the fairing, the angular configuration of the step into smoothly curved formations optimal for low-speed motion in the displacement and transitional modes. Such fairing should ensure a smooth undisturbed flow behind the step and this way minimize the hydrodynamic resistance (i.e., maximize hydrodynamic efficiency, reduce consumption of power and fuel resulting in longer cruising range) of the boat in the displacement and transitional modes.

[0023] Whereas, being retracted and located above the trailing edges (in projection onto the transverse plane), such a fairing will not interfere with the flow separation at the trailing edges and thus provide effective high-speed operation of the boat in planing mode.

[0024] Several examples of this kind of retractable fairing design can be found in applications to the steps of seaplanes and the transoms of conventional planing motorboats.

[0025] However, all of these fairings assume smoothing of the flow behind the bottom or transom steps on flat, non-profiled planing bottoms.

[0026] At the same time, the steps with profiled cambered planing surfaces, which are the subject of this invention, require a special configuration of the fairing to ensure efficient operation. Whereas, for example, the use of conventional configurations of known fairings, in which the tangents to the outer contours are usually horizontal in the areas of contact with the edges of the step, in the case of cambered surfaces forms breaks in the contours and can lead to flow disruption and a corresponding decrease in efficiency.

[0027] As examples of known designs of conventional fairings, there can be mentioned fairings proposed in the inventions: U.S. Pat. No. 4,519,336 regarding a transom fairing for a planing boat, and U.S. Pat. No. 6,042,052 concerning steps of seaplanes.

[0028] In the design of a retractable fairing for the transom of planing boat according to the patent U.S. Pat. No. 4,519,336, the upper forward part of the fairing is pivotally connected to the transom, so that it can be rotated about a transverse horizontal axis from a horizontal position (corresponding low speed mode of the boat and forming a leveled, protrusion-free transition from flat planing surfaces of the bottom upstream of the step to the curved surfaces of the fairing) into the substantially vertical position (exposing the transom step for the planing mode).

[0029] This technical solution, however, has a number of significant drawbacks, some of which, in principle, prevent its use in the application to cambered bottom steps.

[0030] First of all, judging by the patent, this design of the fairing was supposed to be used only for boats with non-profiled flat bottoms, therefore it does not assume any special configurations of the fairing that would take into account the cambered bottom profiling. The basic idea of the vertical arrangement of the retracted fairing along the transom in practice would lead to the fact that, considering realistic fairing length, the fairing in the retracted position would probably protrude above the deck of the boat and clutter the stern, creating inconvenience during operation of conventional boats, that would make such fairing inappropriate, e.g., for fishing boats and incompatible with transom swim platforms, while, as for the use in application to the shallow bottom steps considered here, such a design of the retractable fairing seems completely unacceptable.

[0031] When used, as intended in the patent U.S. Pat. No. 4,519,336, only as a transom fairing, as an additional drawback, the long vertically raised fairing leads to a rise in the center of gravity of the boat and a decrease in the metacentric height, which negatively affects the transverse stability of the boat, while the additional inertial forces of the raised fairing increase the unfavorable outward roll when turning the boat at speed.

[0032] When considering the patent U.S. Pat. No. 4,519,336, it should also be noted that the patent's claims, stipulating the establishment of a “laminar water flow when said hollow body (i.e., fairing) is in its lowermost (i.e., operational) position”, are practically impossible to implement at real operational speeds of the boat in displacement mode.

[0033] In real boats moving at speeds that make practical sense in the displacement mode (for which it makes sense to use such fairings), the flow at the transom (and, so, on the fairing) is always not laminar, but turbulent.

[0034] To illustrate this, as a rough example, consider a small boat with a displacement of 1 m3 (35.3 cubic feet) and a waterline length of 5 m (16.4 feet) moving in the displacement mode at a speed of about 6 knots, which corresponds to a Froude number: FrD about 1. For such a boat, the laminar flow in the bow part of the wetted hull will be maintained up to approximately Reynolds numbers of 5.105, which correspond to a laminar flow length of about 0.16 m (6.3 inches), after which the flow becomes turbulent. That is, for this boat, the flow will be turbulent for the remaining and overwhelming 4.84 m (15.9 feet), i.e., 96.8% of the bottom length, so that it inevitably will be turbulent at the transom.

[0035] Larger boats operating in the displacement mode at similar Froude numbers, and especially real boats with a less than perfectly smooth bottom surface, will have an even smaller length of the laminar flow in the bow part of the wetted hull than the above small boat, which makes it virtually impossible to achieve laminar flow at the transom, and thereby makes the claims of the patent U.S. Pat. No. 4,519,336 practically unrealizable. Theoretically, for the considered before 5 m (16.4 feet) boat with a perfectly smooth bottom, the laminar flow can reach the transom at Froude numbers no higher than 0.032, which sets the upper limit of applicability of the patent U.S. Pat. No. 4,519,336 and corresponds to the speed of the specified boat of less than 0.2 knots (about 4 inches per second). For larger and real bottom roughness boats this speed limit is much lower, of course, so operating boats at such negligible speeds loses practical meaning.

[0036] In the seaplane applications, according to the patent U.S. Pat. No. 6,042,052, the fairing, hinged at its aft pat to the fuselage, can rotate, shifting its leading edge vertically, which either exposes the trailing edge of the step, ensuring effective planing during takeoff, or covers it in flight, forming a leveled, protrusion-free transition from flat bottom planing surfaces at the step to streamlined surfaces of the tail of the seaplane.

[0037] It should be noted that, unlike the planing boats considered here, the fairing, according to the patent U.S. Pat. No. 6,042,052, should expose the step at relatively low speeds of the transitional takeoff mode and cover it in the main operational mode of flight at high speeds, whereas in the case of boats, on the contrary, the fairing should be used (be in the lower position and cover the transom step) at low speeds of the displacement and transitional modes and should be raised above trailing edges of bottom surfaces at the step in the main high-speed mode of motion of the planing boat.

[0038] In general, although the method of retracting of the fairing is quite suitable for stepped bottom boats, as in other similar designs of step fairings, the fairing according to patent U.S. Pat. No. 6,042,052 is applicable only to flat bottom surfaces and the patent doesn't consider any possible fairing configurations applicable to cambered bottom surfaces.

[0039] Specifically, the claims of the patent U.S. Pat. No. 6,042,052 assume that “a lower fairing portion” should have “a cross-sectional shape conforming to a cross-sectional shape of the shape of the at least one hull at an edge of the hydrodynamic step”.

[0040] That is, the invention according to the patent U.S. Pat. No. 6,042,052 involves only conformity of cross sections of the fairing and the step and does not take into account the longitudinal profile of the bottom surfaces at the step, while implementation of the fairing following the above claims, in practice, when applied to the cambered bottom surface, will lead to the above-mentioned broken flow contours and a corresponding disruption of the flow and decrease in the efficiency of the fairing.

[0041] Consequently, when examining the existing prior art in this field, one can find examples of retractable fairings for steps of planing boats with flat bottom surfaces. However, none of the designs found in the prior art suggests a solution that provides an optimal configuration of the retractable fairing for the step with the profiled cambered planing surface, which would minimize hydrodynamic resistance and ensure high efficiency of the planing boat when moving in displacement and partially transitional modes, while not compromising the main high-speed planing mode of the boat.

[0042] The solution to this issue in accordance with the present invention is to give the fairing a shape that takes into account the downward bend of the profile of the cambered planing surface of the step, ensures that the leading edges of the fairing are aligned flush with the trailing edges of the step and a subsequent gradual transition to the ascending contours of the fairing, ensuring a smooth, non-separation flow in its aft part.

[0043] Specifically, plotting of such required contours of the fairing (ensuring smooth, separation-free flow behind the step at the trailing edges of cambered planing surfaces) must meet the following conditions:

[0044] the leading edge of the fairing in its lower operational position, corresponding low-speed displacement and transitional modes of the boat, is shaped to conform to, abuts upon and fits flush with the trailing edge of cambered planing surface of the step;

[0045] along the line of abutment of the leading and trailing edges, in sections by vertical longitudinal planes, the angles of inclination of tangents to the outer contours of the sections of the cambered planing surface and the surface of fairing are equal and positive, i.e., the tangents are turned counterclockwise relative to the horizon at angles less than 90 degrees when viewed from the starboard side of the boat;

[0046] in the same sections by vertical longitudinal planes, when moving aft along at least the forward part of the contours of the fairing outer surface, the angles of inclination of the tangents to the contours gradually decrease and, at some distance aft from the leading edge, the tangents come to the zero-angle horizontal position, and then the angles of inclination of the tangents become negative, while their moduli (absolute values) increase when moving along the contour of the fairing further aft, so that, when moving aft along at least the forward part of the contours of the fairing outer surface, the tangents to the contours of the fairing rotate clockwise, when viewed from the starboard side of the boat, at angles greater than the initial angles of inclination of the tangents to the horizon at the point corresponding to the abutment of the outer contours of the cambered planing surface and the fairing, forming convexities of the outer contours of the fairing and a bulge of the fairing arranged along the trailing edge and protruding downwards below the trailing edge in projection onto the transverse plane.

[0047] The formation of the fairing contour further aft beyond the bulge can be achieved either by continuing a gradual rotation of the tangent to the contour clockwise, when viewed from the starboard side of the boat, which provides a convex shape of the fairing in its rear part with ascending contours of the sections, or by straight lines connecting the rearmost points of the sections of the bulge with the rear edges of the fairing (preferably maintaining the slope of the lines corresponding to the slope of the tangent to the contour of the bulge convexity at its end), or by gradual rotation of the tangent counterclockwise to a substantially horizontal position, thus forming a concave contour of the outer surface of fairing at its aft part, which ensures, in the application to the bottom step, the alignment of the aft section of the fairing with the surfaces of the bottom of the boat behind the fairing.

[0048] Thus, the above-described fairing configuration solves the problem of increasing the efficiency of boats with a stepped bottoms and cambered planing surfaces at low Froude numbers before reaching full-scale planing. At the same time, as noted above, to ensure effective operation of the boats in their main high-speed planing mode, the flow of water along planing bottom surfaces must come off the trailing edges of the cambered planing surfaces, for which purpose these trailing edges must be exposed (from behind) to atmospheric air by means of the retractable design of the fairing.

[0049] In the application to the considered configuration of the fairing for a step with a cambered planing surface, this means that in the planing mode the fairing should be raised to its upper inactive position, in which the leading edge of the fairing, the bulge and the fairing as a whole, should be located higher than the trailing edge of the cambered planing surface in projection onto the transverse plane.

[0050] This can be practically implemented in a number of embodiments, among which for the bottom step the simplest is probably the design of a fairing pivotally connected to the hull (specifically, to the bottom structure) along the rear edge of the fairing and capable of rotating on hinges attached to the bottom structure with rotation axes running generally along the edges of the step, i.e., the trailing edges of the planing surface.

[0051] Thus, being in the lower operational position (ensuring the alignment of the edges of the fairing and the step) and being pulled up (into a bottom recess behind the step), for example, by a hydraulic or electro-hydraulic actuator (located and secured inside the boat hull), the fairing will turn upward on its hinges and come to its upper inactive position, exposing the trailing edges of the cambered planing surfaces and not impeding the flow coming off the edges and, thus, ensuring effective movement in planing mode. Such fairing can be made in the form of a panel consisting of a shell curved to the required configuration (with a bulge and a bent or straight tail section), reinforced with stiffening ribs (with hinge eyes for connecting the actuator) and equipped with hinge knuckles on the rear edge for connection to hinge sockets fixed to the bottom structure. Taking into account the deadrise of the bottom and the typical swept-back configuration of the cambered planing surface of the bottom step, it is expedient to divide the fairing for the bottom step into two halves symmetrical relative to the central plane, each of which can rotate on hinges with axes parallel or so to the corresponding edges of the steps (i.e., along the trailing edges of the cambered planing surfaces of the step).

[0052] That is, since the dihedral cambered planing surfaces corresponding to the bottom step usually have a hydrodynamically justified swept-back configuration, the axes of rotation of the hinges on the rear edges of the fairing halves in the plan view will also be inclined to the aft part of the keel line of the boat at an angle less than 90 degrees and arranged at a certain angle of deadrise in projection onto the transverse plane.

[0053] Although hydrodynamic characteristics of cambered planing surfaces can significantly exceed those of flat planing surfaces, it is problematic for a single cambered planing surface on the bottom of the boat to realize its high potential efficiency due to its inability to maintain the optimum trim angle, i.e., the optimum angle of incidence relatively the flow ensuring the highest possible efficiency (which in simple terms is characterized by the ratio of the planing surface's dynamic lift to its drag). Moreover, inability to keep the angle of attack can lead to loss of dynamic stability such as porpoising, which questions the direct practical use of the single cambered planing surface configuration.

[0054] Therefore, in order to secure the required (most effective) angular position of the cambered planing surface, the hydrodynamic configuration of a boat with such a surface must be provided with an additional stabilizing surface, which, for increased efficiency, should also be given a cambered planing surface and located further aft lengthwise.

[0055] Thus, as a reasonable hydrodynamic configuration, the bottom of the boat should be equipped with at least two planing surfaces successively arranged lengthwise: the main cambered planing surface (i.e., generating the bulk of dynamic lift), related to the step in the middle part of the bottom, and the stabilizing surface located at the transom. Correspondingly, the considered above in application to the main bottom step configuration of the fairing according to this invention, can also be used as a fairing for the transom step provided with the stabilizer featuring cambered planing surface.

[0056] In this case, while maintaining the shape of the fairing determined by this invention, which ensures effective smoothing of the flow behind the transom step formed by the trailing edges of the stabilizer with cambered planing surface, for retraction (ensuring the operation in the main planing mode), embodiments of such a fairing for transom cambered stabilizer can use known conventional methods of lifting transom fairings to the position above the transom trailing edges (in projection onto the transverse plane), including use designs of foldable retractable transom fairings corresponding to the patent application Ser. No. 19 / 009,993 (“Planing Boat with Foldable Fairing”).

[0057] That is, the embodiments of the fairing for the transom stabilizer with cambered planing surfaces (which fairing ensures the progression of the tangents to the fairing contours and the formation of the bulge specified by this invention) may include:

[0058] foldable designs, when the fairing consists of at least two parts arranged successively along the length of the boat, while an after part can be slid or rolled forward into a hollow forward part, or can be rotated around the transverse axis relative to the forward part to be folded over it in order to reduce length of the fairing;

[0059] retractable embodiments of the fairing, which involve its vertical lifting, its folding upward by rotation around the transverse axis, or suspension on the transom using parallelogram mechanisms.

[0060] All the mentioned methods of folding and retracting the transom fairing can be implemented using hydraulic or electrohydraulic actuators, worm gears driven by electric motors, electric linear actuators, or manually (in the case of smaller boats).

[0061] Similar to the forward bottom step with its cambered planing surface, in application to the transom stabilizer it should also be established that:

[0062] the leading edge of the transom fairing in its lower operational position, corresponding low-speed displacement mode of the boat, is shaped to conform to, abuts upon and fits flush with the trailing edge of cambered planing surface of the transom stabilizer;

[0063] along the line of abutment of the leading and trailing edges, in sections by vertical longitudinal planes, the angles of inclination of tangents to the outer contours of the aft stabilizing cambered planing surface and the surface of transom fairing are equal and positive, i.e., the tangents are turned counterclockwise relative to the horizon at an angle less than 90 degrees when viewed from the starboard side of the boat;

[0064] in the same sections by vertical longitudinal planes, when moving aft along at least the forward part of contours of the fairing outer surface, the angles of inclination of the tangents to the contours gradually decrease and, at some distance aft from the trailing edge, the tangents come to the zero-angle horizontal position, and then the angles of inclination of the tangents become negative, while their moduli (absolute values) increase when moving along the contour of the fairing further aft, so that, when moving aft along at least the forward part of the contours of the fairing outer surface, the tangents to the contours of the fairing rotate clockwise, when viewed from the starboard side of the boat, at angles greater than the initial angles of inclination of the tangents to the horizon at the points corresponding to the abutment of the outer contours of the cambered planing surface and the fairing, forming convexities of the outer contours of the fairing and a bulge of the fairing arranged along the trailing edge of the transom and protruding downwards below this trailing edge in projection onto the transverse plane.

[0065] The contours of the transom fairing further aft the bulge can be formed by straight or curved lines (convex, e.g., as they are usually more preferable for displacement mode), while keeping the same tangent angle at the junction with the contour of the bulge.

[0066] Similarly, in the planing mode, the transom fairing for the cambered planing surface of stabilizer should be raised to its upper inactive position, in which the leading edge of the fairing, the bulge and the fairing as a whole, should be located higher than the trailing edge of the cambered stabilizer in projection onto the transverse plane.

[0067] As an example of possible foldable and retractable embodiment of such transom fairing according to the present invention, there can be considered a fairing consisting of two parts arranged successively lengthwise in its lower operational position (corresponding to the low-speed displacement mode), while the after part can be slid or rolled forward into the hollow forward part, which is enabled by tapering aftward configuration of the fairing. Such folding can be practically implemented, e.g., by providing the more forward part with longitudinal rails attached from below to the upper surface of its shell, along which the after part of the fairing can slide or roll (if this rail track is equipped with rollers) forward until it stops, ensuring the complete placement inside the cavity of the hollow forward part. Longitudinal movement along the rail track of the after part forward (to fold the fairing when it is in its upper inactive position) and backward (to unfold the fairing when it is deployed into its lower operational position) can be provided by a longitudinally arranged and centrally located electric linear actuator (ball screw drive), the front and rear ends of which are secured in the front and rear extremities of the more forward part of the fairing (attached from below to the upper surface of its shell, e.g.), and the ball nut of the drive is attached to the front end of the after part. In this case the rotation of the linear drive screw, provided by the electric motor, leads to the longitudinal movement of the ball nut, which pulls forward or pushes back the after part.

[0068] As for the retractility of the fairing, the front part of the fairing, adjacent to the transom, can be suspended on the transom by means of double-lever parallelogram mechanisms with rotation axes normal to the boat's centerline plane, which can be embodied in the form of a pair of double-lever parallelogram mechanisms located inside of the fairing shell and spaced transversely and symmetrically relative to the center plane of the boat on both sides of the fairing. So that by turning the levers (by means of hydraulic or electrohydraulic actuators) clockwise, when viewed from the starboard side, the front part of the fairing with the after part folded into its cavity, is moved upward from the lower operational position (from abutting against the trailing edge of the bottom), to the inactive upper position above the trailing edge in the transverse projection.

[0069] The transom fairing compactly packed in this way can be placed, for example, under a swim platform of boat or motor yacht, which arrangement doesn't increase and completely preserves the original dimensions of the boat in planing mode and at rest.

[0070] In the case of using the considered transom fairing on boats employing stern drives, surface drives or outboard motors as their propulsion means, the part of said fairing adjacent to the transom is to be provided with recesses shaped to accommodate these propulsion means, which recesses must ensure steerability and trimability such drives.

[0071] The sections of the transom fairing can be made in the form of either hollow water-permeable thin-walled shells or volumetric structures having certain buoyancy.

[0072] In the latter case, the additional buoyancy of the fairing parts in displacement mode must be taken into account because it could affect the trim of the boat.

[0073] The water-permeable hollow thin-walled structures of the fairing do not have significant buoyancy and should not cause noticeable problems with the boat's trim in the displacement mode. However, the water masses accumulated in the fairing cavity while floating increase the boat's inertia and, so, can affect the boat's dynamics as well as its trim when getting on plane.

[0074] As regards the divided in halves embodiment of the bottom fairing and some possible embodiments of the transom fairing, the considered accumulation of water should not present any particular problems due to the fact that the tilt of the fairing during its retraction should result in rapid removal of water from the cavities of the fairing parts. For some other embodiments, in this regard, it is advisable to provide the bottom sections of the fairing with drainage holes or slots, in order to speed up the removal of water from the fairing cavity and to neutralize the above negative impact on the boat.

[0075] To increase the strength and rigidity of the fairing shells, they can be made three-layer with foam, balsa or honeycomb filler and (or) reinforced with internal frames and stringers. The structural designs of the aft sliding along part can also include bulkheads.

[0076] Thus, giving both the bottom and transom fairings a configuration consistent with the cambered planing surfaces of the bottom step and transom stabilizer according to this invention, forms in the lower operational position of the fairings (corresponding to displacement and partially transitional modes) a single continuous smooth surface of the boat bottom (without bottom and transom steps), which ensures a smooth, separation-free flow all through the length of the bottom, resulting in low hydrodynamic drag (i.e., high hydrodynamic efficiency) and corresponding reduction of consumption of power and fuel, leading to an increase in cruising range, that is, to a general improvement in the operational properties of the boat in the low-speed cruising modes.

[0077] At the same time, being retracted into the upper inactive position above the trailing edges of corresponding cambered planing surfaces (including by the methods mentioned above), the bulged fairings according to this invention do not compromise the operation of the boat in its main high-speed planing mode of movement.

[0078] Summarizing the above, we can conclude that known designs of fairings for planing boats cruising in low-speed displacement mode do not offer solutions for the most hydrodynamically advanced stepped hull boats with cambered planing surfaces. That is, they do not define proper configuration of fairings consistent with such profiled surfaces. Suffice it to say that none of the known designs of fairings of the prior art mention the need to rotate the tangents to the longitudinal contours of the fairing at an angle greater than the initial positive angle at the point of contact with the trailing edge of the cambered planing surface and to form a bulge protruding below the trailing edges, which is indispensable to ensure a smooth, continuous flow behind the trailing edges. That is, only such configuration can prevent disturbance of flow along the edges of the steps (i.e., the trailing edges of cambered planing surfaces) and can form a smooth, separation-free flow along the entire bottom of the stepped hull boat with profiled planing surfaces and this way ensure efficient (with low hydrodynamic resistance) operation in the low-speed displacement and partially transitional modes, resulting in reduction of consumption of power and fuel, longer cruising range, and, thus, the highest efficiency of such boats in the widest operational range of Froude numbers.

[0079] Accordingly, the object of this invention is to provide a solution regarding the optimal configuration of the fairing for the advanced stepped hull boats with cambered planing surfaces, so that the proper configuration of the fairing would ensure minimum drag in the low-speed displacement and partially transitional modes, which is achieved by means of the fairing shape featuring specific progression of tangents to the contours of the fairing, leading to formation of a bulge protruding below the trailing edges and a smooth, separation-free low-drag shape of the boat bottom, while the retractability of the fairing ensures efficient operation of the boat in its main high-speed planing mode.SUMMARY OF THE INVENTION

[0080] The present invention provides a solution to the problem of reducing hydrodynamic resistance and increasing the efficiency of the most hydrodynamically advanced stepped hull planing boats with cambered planing surfaces in displacement and partially transitional modes, without having a negative effect on the operation of the boats in the main high-speed planing mode, which involves the use of retractable fairings for steps on boats' bottoms. Known designs of retractable transom fairings, which assume a flat, non-profiled planing bottom, so that when applied to the profiled (cambered) planing surface of the step, they can lead to flow separation, increased drag and reduced efficiency of the fairing, do not provide a solution to this problem, while some of them are generally incompatible with bottom steps. Following the present invention, the solution regarding the step fairings for displacement and partially transitional modes of the stepped hull boats with cambered planing surfaces is achieved by giving the fairing a special shape consistent with the cambered planing surfaces.

[0081] Like the known fairing designs, the step fairing according to this invention, in its lower operational position corresponding to the low-speed displacement mode, along its leading edge should conform to and abut upon the trailing edge of the step.

[0082] At the same time, taking into account the profile of the cambered planing surface of the step, following this invention, such a fairing must have a configuration determined by the requirements for its outer contours in longitudinal vertical sections, establishing:

[0083] equality of the angles of inclination of tangents to the outer contours of the sections of the cambered planing surface of boat bottom and the surface of fairing at points of their abutment, which angles should be positive, that is, the tangents should be turned counterclockwise relative to the horizon at an angle less than 90 degrees when viewed from the starboard side of the boat, and

[0084] gradual rotation clockwise of the tangents to the outer contours of the fairing when moving aft along at least its forward part, at angles greater than the initial angles of inclination of the tangents to the horizon at the points corresponding to the abutment of the outer contours of the cambered planing surface and the fairing, so that the angles of inclination of the tangents to the horizon gradually decrease, then the angles come to the zero corresponding to the horizontal position of the tangents, and then the angles become negative, while their moduli (absolute values) increase, resulting in formation of convexities of the outer contours of the fairing and a bulge of the fairing arranged substantially along the trailing edge and protruding downwards below the trailing edge.

[0085] This configuration of the fairing according to this invention provides a smooth, continuous and separation-free flow aft of the bottom step, while the same configuration can also be used for the transom fairing behind the stabilizing planing surface of the cambered profile, which forms a single continuous smooth surface of the boat bottom, ensuring a through separation-free flow along the bottom with minimal resistance in displacement and partially transitional motion modes. Whereas, when the boat is in its main operational high-speed planing mode, both the bottom and transom fairings supposed to be retracted to their upper inactive position, in which the leading edges of the fairings, said bulges and the fairings as a whole, are to be located higher than the trailing edges of cambered planing surfaces of the bottom and transom steps in projection onto the transverse plane, to expose trailing edges required for the planing.

[0086] Thus, the step fairing according to this invention improves the efficiency of stepped hull planing boats in displacement and partially transitional operating modes, without compromising the operational properties of boats in the main high-speed planing mode, and this way ensures highest efficiency of the boat in widest range of Froude numbers. Various embodiments are disclosed herein for the method and apparatus related to the special designs of retractable fairings intended to reduce hydrodynamic resistance and increase the efficiency of stepped hull planing boats with cambered planing surfaces in the displacement and partially transitional modes of motion, not compromising the operation of boats in the main high-speed planing mode at high Froude numbers.

[0087] In some embodiments, parts of the contours of the outer surface of the fairing aft of said convexities are straight lines.

[0088] In some embodiments, the angles of inclination to the horizon of the straight lines aft of the convexities are substantially equal to the angles of inclination of the tangents to said convexities at their rearmost points.

[0089] In some embodiments, the tangents to the outer contours of the fairing, when moving aft along the contours and aft of said convexities, gradually turn counterclockwise when viewed from the starboard side of the boat, forming a concave contour of the outer surface of fairing in its aft part.

[0090] In some embodiments, at least one fairing is movable substantially vertically relative to the boat hull.

[0091] In some embodiments, at least one fairing is rotatable relative to the boat hull about an axis at the aft part of the fairing.

[0092] In some embodiments, at least one fairing is suspended on the hull by means of at least one double-lever parallelogram mechanism comprising levers and hinges at the ends of these levers, so that the hinges of one end of the levers are attached to the hull, and the hinges of the other end of the levers are attached to the fairing.

[0093] In some embodiments, a planing boat has at least two cambered planing surfaces, successively arranged lengthwise, and at least one fairing is located aft of each of said cambered planing surfaces breadthwise.

[0094] In some embodiments, a planing boat has a bottom step with a swept back substantially dihedral forward cambered planing surface, symmetrical relative to its vertical longitudinal center plane, wherein each symmetrical relative to the center plane half of said forward planing surface is provided with its own fairing, rotatable relative to the hull around an axis in the aft part of the fairing, which axis in the plan view is arranged at an angle less than 90 degrees to the aft part of boat keel line, and inclined at some angle of deadrise in projection onto the transverse plane.

[0095] In some embodiments, the axis of rotation of each half of the fairing behind the adjacent half of the forward planing surface is substantially parallel to the corresponding trailing edge of the forward cambered planing surface.

[0096] In some embodiments, the transom fairing of the boat with at least two cambered planing surfaces successively arranged lengthwise, comprises at least two parts, successively arranged lengthwise when in the low operational position, while the rear part of the fairing is made movable relative to the adjacent front part.

[0097] In some embodiments, the rear part of the transom fairing consisting of at least two parts, successively arranged lengthwise when in the low operational position, can be moved along forward into the cavity of the adjacent hollow front part of the fairing.

[0098] In some embodiments, the rear part of the transom fairing consisting of at least two parts, successively arranged lengthwise when in the low operational state, is made rotatable relative to the adjacent front part about a substantially normal to the center plane axis and can be rotated forward for folding over the front part of the fairing.

[0099] In some embodiments, the shell of the fairing is reinforced with frames and stringers.

[0100] In some embodiments, the fairing is hollow and provided with drainage holes or slots.

[0101] In some embodiments, the transom fairing is provided with at least one recess shaped to accommodate outboard motor, stern drive or surface drive.

[0102] In some embodiments, the fairing, movable relative to the hull as a whole, as well as each movable part of the fairing, are driven by at least one hydraulic or electrohydraulic actuator, a worm drive or electric linear actuator.BRIEF DESCRIPTION OF THE DRAWINGS

[0103] The accompanying drawings, which are incorporated herein and constitute a part of this specification, illustrate exemplary embodiments and, together with the general description given above and the detailed description given below, serve to explain the features of the various embodiments.

[0104] FIG. 1 depicts a schematic diagram illustrating the side elevation view of a stepped hull planing boat with cambered planing surfaces, floating on the surface of water and provided with bottom and transom fairings according to some embodiments, which fairings are deployed for operation in displacement and partially transitional modes.

[0105] FIG. 2 depicts a schematic diagram illustrating the side elevation view of a stepped hull planing boat featuring cambered planing surfaces and provided with bottom and transom fairings according to some embodiments, wherein the depicted boat represents basically the same boat as shown in FIG. 1, but with the fairings folded and retracted for operation in the main high-speed planing mode.

[0106] FIG. 3 depicts a schematic diagram illustrating the plan bottom view of a stepped hull planing boat featuring cambered planing surfaces and provided with bottom and transom fairings according to some embodiments, wherein the depicted boat represents basically the same boat as shown in FIG. 1 with the fairings shown lowered, unfolded and deployed for operation in displacement and partially transitional modes.

[0107] FIG. 4 depicts a schematic diagram illustrating the plan bottom view of a stepped hull planing boat featuring cambered planing surfaces and provided with bottom and transom fairings according to some embodiments, wherein the depicted boat represents basically the same boat as shown in FIG. 2 with the fairings shown folded and retracted for operation in the main high-speed planing mode.

[0108] FIG. 5 depicts a schematic diagram illustrating a sectional view corresponding to section 1-1 in FIG. 3 and shows a broken-away portion of the boat at the bottom step with the bottom fairing unfolded for operation in displacement mode.

[0109] FIG. 6 depicts a schematic diagram illustrating a sectional view corresponding to section 3-3 in FIG. 4 and shows a broken-away portion of the boat at the bottom step with the bottom fairing retracted for operation in planing mode.

[0110] FIG. 7 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 1 and FIG. 3, provided with the transom fairing according to some embodiments, wherein the fairing, suspended on the transom by means of double-lever parallelogram mechanisms, is shown unfolded and lowered for operation in displacement and partially transitional modes.

[0111] FIG. 8 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 2 and FIG. 4, provided with a transom fairing according to some embodiments, wherein the fairing, suspended on the transom by means of double-lever parallelogram mechanisms, is shown folded and raised to its inactive position, ensuring effective operation of the boat in the main planing mode.

[0112] FIG. 9 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 1 and FIG. 3, provided with the transom fairing according to some embodiments, wherein the fairing, unfolded and lowered for operation in displacement mode, is shown in a sectional view corresponding to section 2-2 in FIG. 3.

[0113] FIG. 10 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 2 and FIG. 4, provided with the transom fairing according to some embodiments, wherein the fairing, folded and raised for operation in planing mode, is shown in a sectional view corresponding to section 4-4 in FIG. 4.

[0114] FIG. 11 depicts a schematic diagram illustrating a view of the transom fairing when looking aft from the transom, corresponding to the view designated by the letters A-A in FIG. 9, in which the fairing is shown unfolded and lowered for operation in displacement and partially transitional modes.

[0115] FIG. 12 depicts a schematic diagram illustrating a perspective view of a half of the bottom fairing according to some embodiments, wherein the shell of the fairing featuring convex tail section is reinforced with stringers.

[0116] FIG. 13 depicts a schematic diagram illustrating a perspective aft bottom view of a stepped hull planing boat featuring cambered planing surfaces, provided with bottom and transom fairings according to some embodiments, wherein the fairings are shown lowered, unfolded and deployed for operation in displacement and transitional modes.

[0117] FIG. 14 depicts a schematic diagram illustrating a perspective aft bottom view of a stepped hull planing boat featuring cambered planing surfaces, provided with bottom and transom fairings according to some embodiments, wherein the fairings are shown folded and retracted for operation in high-speed planing mode of motion.DETAILED DESCRIPTION OF THE INVENTION

[0118] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the claims.

[0119] FIG. 1 depicts a schematic diagram illustrating the side elevation view of a stepped hull planing boat featuring cambered planing surfaces, floating on the surface of water and provided with bottom and transom fairings according to some embodiments, located behind bottom and transom steps, wherein the fairings are shown lowered, unfolded and deployed for operation in displacement and partially transitional modes.

[0120] The planing boat 101, floating being submerged up to the waterline “WL” corresponding to the stationary displacement state, has a substantially vertical transom 102, sides 103, dihedral bottom surfaces 104, chines 105, a keel line 106 and a swim platform 107.

[0121] As a stepped hull planing boat with cambered planing surfaces, the shown boat 101 features a hydrodynamic system comprising a bottom step provided with a dihedral and swept-back cambered planing surface 108, as the forward planing surface of the hydrodynamic system, with its trailing edges 109 representing the edges of the bottom step, and a dihedral aft stabilizing cambered planing surface 110 with its trailing edges 111 representing the lower edges of the transom 102, wherein cambered planing surfaces 108 and 110 are arranged successively along the bottom 104 of the boat 101 and represent a single interconnected hydrodynamic planing system of the boat 101.

[0122] The boat 101 is provided with a system of movable relative to the hull of the boat 101 retractable fairings comprising a swept-back dihedral bottom fairing 112, divided breadthwise into two halves, each of which with its leading edge 113, a bulge 114, a straight tail section 115 and a rear edge 116 that extends along the axis of rotation of each half of the fairing 112 and is substantially parallel to the swept-back trailing edge 109 (i.e., the edge of the bottom step) of the forward cambered planing surface 108, and a transom fairing consisting of a hollow front part 117 with its leading edge 118, a rear edge 119 and an upper edge 120, and an after part 121 movable relative to the front part 117, while the shape of the transom fairing features a bulge 122 and a convex tail section 123, which retractable fairings, i.e., the bottom fairing 112, as well as the front part 117 and the after part 121 of the transom fairing, are shown in their lower unfolded operational positions corresponding to displacement and transitional modes.

[0123] The lower operational position of the bottom fairing 112 presupposes that its leading edge 113, which is shaped to conform to the trailing edge 109 of the forward cambered planing surface 108, abuts upon and fits flush with the trailing edge 109.

[0124] To ensure a smooth, continuous and separation-free flow along the bottom 104 at the bottom step (at and aft of the trailing edge 109) during the low-speed cruising in displacement mode, in sections by vertical longitudinal planes, tangents to contours of the bottom fairing 112 at the leading edge 113 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to angles of inclination of tangents to contours of the cambered planing surface 108 at the trailing edge 109.

[0125] Then, following the contours of the fairing 112 aftward, the tangents rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at the leading edge 113.

[0126] Such progression of tangents forms the bulge 114 in the forward part of the bottom fairing 112, which bulge 114 is arranged along the leading edge 113 and trailing edge 109, and protrudes below the trailing edge 109 in projection onto the transverse plane. The tail portion 115 of the fairing 112 is represented in sections by vertical longitudinal planes with straight lines connecting the aft points of the bulge 114 with the rear edge 116. The angles of inclination of these straight lines are equal to the angles of inclination of the tangents to the contours of the bulge 114 at their rearmost points, which means that when moving along the contours, the rotation of the tangents to the contours in the longitudinal vertical sections of the fairing 112 stops at the rear points of the bulge 114 and their angles of inclination are fixed right up to the rear edge 116.

[0127] Similar to the bottom fairing 112, in the lower operational position, the leading edge 118 of the transom fairing is shaped to conform to the trailing edge 111 of the aft cambered planing surface 110, abuts upon it and fits flush with the trailing edge 111.

[0128] To ensure a smooth, continuous and separation-free flow at and behind the transom 102 (at and aft of the trailing edge 111) during the low-speed cruising in displacement mode, in sections by vertical longitudinal planes, tangents to contours of the transom fairing at the leading edge 118 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to angles of inclination of tangents to contours of the aft cambered planing surface 110 at the trailing edge 111.

[0129] Following the contours of the transom fairing aftward, the tangents rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli increase when moving further aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at the leading edge 118.

[0130] Such progression of tangents forms the bulge 122 in the forward part of the transom fairing, which bulge 122 is arranged along the leading edge 118 and the trailing edge 111, and protrudes below the trailing edge 111 in projection onto the transverse plane.

[0131] The tail portion 123 of the transom fairing is represented in sections by vertical longitudinal planes with convex lines behind the rearmost points of the bulge 122, while, at the points of connection, the angles of inclination of tangents to these convex lines and the tangents to the contours of the bulge 122 are equal, which means that the tangents to the contours of the sections of this fairing beyond the bulge 122 continue to gradually rotate clockwise, forming a convex tail shape of the transom fairing.

[0132] Thus, the system of two fairings, i.e., the bottom fairing 112 and the transom fairing consisting of the front 117 and after 121 parts, located, respectively, behind the bottom step and the transom 102 and shaped to match the profiles of the cambered planing surfaces 108 and 110 of the boat 101, in the shown lower operational position, ensures the formation of a continuous smooth bottom surface, providing at small Froude numbers a smooth, continuous and separation-free flow along the bottom of boat 101, which results in low hydrodynamic resistance and the efficient operation of the boat 101 in displacement and partially transitional motion modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat 101.

[0133] At the same time, in order to ensure efficient operation of the boat 101 in its main high-speed planing mode of motion, at high Froude numbers the flow must come off the trailing edges 109 and 111 of planing surfaces 108 and 110, for which the trailing edges 109 and 111 (their back sides) must be exposed to the atmospheric air by means of the formation of substantially vertical steps along the contours of these edges. For this purpose, it is assumed that each half of the bottom fairing 112 is made retractable and can be raised to the upper inactive position by rotation around the axis extending along the rear edge 116, so that, being turned upward (by hydraulic actuator, e.g.), the entire fairing 112, including its bulge 114, would be located above the trailing edges 109 in projection onto the transverse plane, which position should raise the leading edge 113 and form a substantially vertical step, and this way expose the trailing edge 109 and ensure efficient operation of the boat 101 in its main high-speed planing mode.

[0134] As regards the transom fairing, in order to ensure the possibility of exposing the trailing edge 111, necessary for effective planing of the surface 110, it is assumed that the transom fairing is made both foldable and retractable.

[0135] In the FIG. 1 the transom fairing, represented in the shown lower operational position by successively composed front part 117 and after part 121, is assumed to have a smooth continuous surface and a configuration tapering from the transom 102 further aft both in the plan view and, as shown in this side elevation view, with contours rising gradually from the bulge 122 to the waterline “WL”. Such a shape of the fairing ensures a smooth and separation-free flow aft of the transom 102 and results in low hydrodynamic resistance (meaning higher hydrodynamic efficiency), which leads to a decrease in the power required to propel the boat 101, a decrease in fuel consumption and a corresponding increase in cruising range when sailing in the displacement mode.

[0136] The indicated tapering aftward shape of the fairing suggests that, in projection onto the transverse plane, the after part 121 does not extend beyond the boundaries of the contour 119, and, so, can be moved forward into the cavity of the hollow front part 117 (to be completely folded and stored there) by means of, e.g., electric linear actuator.

[0137] At the same time, the swim platform 107 of the boat 101, mounted on the transom 102, extends aftward of the transom 102 and above the waterline “WL”, while the upper edge 120 of the front part of fairing 117 is located below the swim platform 107 and above the waterline “WL”, so that the front part 117 with the after part 121 folded inside its cavity can be raised upward until the upper edge 120 touches the swim platform 107, which can be accomplished, e.g., by parallelogram mechanisms suspending the front part 117 on the transom 102 and driven by hydraulic or electrohydraulic actuators.

[0138] In this case, the leading edge 118 should rise above the trailing edge 111 and expose a substantially vertical surface of the lower part of the transom 102 and thus form a vertical step exposing the trailing edge 111, providing access of atmospheric air to the edge 111 and effective planing of the aft cambered stabilizing surface 110.

[0139] Thus, the fairing can be folded lengthwise to the length of the front part 117 and moved up to the platform 107 to be completely covered by the platform 107 in the plan view (which makes this design compatible with the swim platform 107 and does not affect dimensions of the boat 101), while exposing the tailing edges 111.

[0140] In this way, the combined simultaneous retraction of the bottom fairing 112 (by rotating its halves around the axes at the rear edges 116), as well as the folding the after part 121 into the cavity of the hollow front part 117 and retraction of the transom fairing (pulling it up to the swim platform 107), should expose the trailing edges 109 and 111 of the forward cambered planing surface 108 and the aft cambered planing surface 110, ensuring the efficient operation of the boat 101 in its main high-speed planing mode.

[0141] FIG. 2 depicts a schematic diagram illustrating the side elevation view of a stepped hull planing boat featuring cambered planing surfaces and provided with bottom and transom fairings according to some embodiments, wherein the depicted boat represents basically the same boat as shown in FIG. 1, but with the fairings folded and retracted for operation in the main high-speed planing mode.

[0142] The boat 101, assumed to be in planing mode, has a substantially vertical transom 102, sides 103, bottom surfaces 104, chines 105, a keel line 106 and a swim platform 107.

[0143] As a stepped hull planing boat with cambered planing surfaces, the shown boat 101 features the hydrodynamic system comprising a bottom step provided with a dihedral and swept-back cambered planing surface 108, as the forward planing surface of the hydrodynamic system, with its trailing edges 109 representing the edges of this bottom step, and a dihedral aft stabilizing cambered planing surface 110 with its trailing edges 111 representing the lower edges of the transom 102, wherein cambered planing surfaces 108 and 110 are arranged successively along the bottom 104 of the boat 101 and represent a single interconnected hydrodynamic planing system of the boat 101.

[0144] The boat 101 is provided with a movable relative to the hull of the boat 101 system of fairings shown retracted into their upper inactive position in order to expose the trailing edges 109 and 111 and ensure effective operation in high-speed planing mode, which fairing system comprises a swept-back dihedral bottom fairing 112, divided breadthwise into two halves, each of which with its leading edge (not visible in this upper state), a bulge 114, a straight tail section 115 and a rear edge 116 that extends along the axis of rotation of each half of the fairing 112 and is substantially parallel to the trailing edge 109 of the forward cambered planing surface 108, and a transom fairing shown folded and represented here by only the hollow front part 117 with its leading edge 118, a rear edge 119 and an upper edge 120, while the shape of the transom fairing features a bulge 122 and a convex tail section 123 (shown partially).

[0145] It is assumed that the longitudinal profiling of both the front bottom 112 and transom fairings is made according to the present invention and, so, in their lower operational position, ensures in the vertical longitudinal sections the equality of positive angles of inclination of tangents to the contours of the cambered planing surfaces and fairings at the abutment of the trailing and leading edges, as well as the progressive rotation of the tangents when moving along the contours of the fairings aft, forming bulges 114 and 122, whereas in FIG. 2 the fairings are brought to their upper inactive position exposing the trailing edges 109 and 111 and preventing contact of the fairings with the flow.

[0146] The transom fairing of FIG. 2 in its unfolded state, corresponding low-speed mode, supposed to be composed of two successively arranged lengthwise and adjoining parts (as in the embodiment of FIG. 1), and features a tapering configuration further aft from the transom 102, while because of such rearwardly tapering configuration of the fairing, the after part of the fairing does not extend beyond the boundaries of the contour 119 of the front part 117 in projection onto the transverse plain, and, so, when moved forward, the after part can be folded and placed inside the hollow front part 117. Thus, in the FIG. 2 it is assumed that the after part is pulled into the cavity of the hollow front part 117, is accommodated there in its folded position and, so, not visible here, which reduces the length of the transom fairing to the length of its front part 117, while the swim platform 107 completely covers the front part of the fairing 117 in the plan view.

[0147] As it was mentioned in application to the embodiment of the FIG. 1, in order to ensure efficient operation of the boat 101 in its main high-speed planing mode of motion, at high Froude numbers the flow must come off the trailing edges 109 and 111 of planing surfaces 108 and 110, for which the trailing edges 109 and 111 (their back sides) must be exposed to the atmospheric air by means of the formation of vertical steps, like the shown step 201 along the contour of the edge 111. For this purpose, in FIG. 2 the bottom fairing 112 is retracted, i.e., raised to the upper inactive position by rotating its halves around the axes extending along their rear edges 116, so that each half is turned upward (by hydraulic actuator, e.g.), thereby providing that the entire fairing 112, including its bulge 114, is located above the trailing edges 109 in projection onto the transverse plane, which resulted in raising the leading edge 113 and the formation of a substantially vertical step, and this way exposing the trailing edge 109 and ensuring the efficient operation of the boat 101 in its main high-speed planing mode.

[0148] The transom fairing represented here by the front part 117 (assuming that the after part is folded inside its cavity) is supposed to be suspended on the transom 102 on parallelogram mechanisms driven by hydraulic or electrohydraulic actuators. So, by pulling the parallelogram mechanisms' levers upwards using actuators, the transom fairing (visible as the front part 117) was raised to its upper inactive position, thus lifting the leading edge 118 above the trailing edge 111, forming the vertical step 201 of the transom 102, exposing the trailing edges 111, ensuring access of atmospheric air to the edges 111 and the effective planing of the aft cambered stabilizing surface 110.

[0149] In the depicted configuration of FIG. 2, where the boat 101 is equipped with a swim platform 107, the transom fairing represented by the front part 117 can be raised until its upper edge 120 touches the lower part of the platform 107. By means of this, considering that in this embodiment the swim platform 107 totally covers the front part 117 of the transom fairing in the plan view, the compactly folded transom fairing is entirely placed under the swim platform 107, which makes this design completely compatible with the platform 107 and does not increase the dimensions of the boat 101. Thus, this embodiment of the stepped hull boat 101 featuring cambered planing surfaces and equipped with the system of foldable retractable fairings being consistent with said cambered planing surfaces according to this invention, providing in the lower operational position of the fairings low hydrodynamic resistance in the displacement mode of motion (i.e., increasing hydrodynamic efficiency), resulting in low power and fuel consumption, and a corresponding increase in the cruising range (i.e., improving the operational properties of boats), ensures in the shown upper inactive state of the fairings exposure of trailing edges 109 and 111 of planing surfaces 108 and 110 of the boat 101 and efficient operation of the boat 101 in its main high-speed planing mode.

[0150] FIG. 3 depicts a schematic diagram illustrating the plan bottom view of a stepped hull planing boat featuring cambered planing surfaces and provided with bottom and transom fairings according to some embodiments, wherein the depicted boat represents basically the same boat as shown in FIG. 1 with the fairings shown lowered, unfolded and deployed for operation in displacement and partially transitional modes.

[0151] The planing boat 101, shown presumably operating in the low-speed displacement mode, has a substantially vertical transom 102, sides 103, bottom surfaces 104, chines 105, a keel line 106 and a swim platform 107.

[0152] As features characterizing the boat 101 as a stepped hull planing boat with cambered planing surfaces, the hydrodynamic system of boat 101 comprises a bottom step provided with a dihedral swept-back cambered planing surface 108, as the forward planing surface of the hydrodynamic system, with its trailing edges 109 representing the edges of this bottom step, and an aft cambered planing surface 110 with its trailing edges 111 representing the lower edges of the transom 102, wherein cambered planing surfaces 108 and 110 are arranged successively along the bottom 104 of the boat 101 and represent a single interconnected hydrodynamic planing system of the boat 101.

[0153] The boat 101 is provided with a system of retractable fairings shown brought to their lower operational position (upper position in this bottom view) in order to cover the trailing edges 109 and 111 from behind, maintaining a smooth, continuous and separation-free flow along the entire bottom, and this way ensuring effective operation of the boat 101 in displacement and partially transitional modes, which fairing system comprises a swept-back dihedral bottom fairing 112, divided breadthwise into two halves, each of which with its leading edge 113, a bulge 114, a tail section (which is assumed to be concave) and a rear edge 116 that extends along the axis of rotation of each half of the bottom fairing 112 and is substantially parallel to the swept-back trailing edge 109 (i.e., the edge of the bottom step) of the forward cambered planing surface 108, and a transom fairing consisting of a hollow front part 117 with its leading edge 118 and a rear edge 119, and an after part 121 adjoined, movable and arranged successively lengthwise relative to the front part 117, while the shape of the transom fairing features a bulge 122 and is assumed to be convex aft of the bulge 122.

[0154] The lower operational position of the bottom fairing 112 presupposes that its leading edge 113, which is shaped to conform to the trailing edge 109 of the forward cambered planing surface 108, abuts upon and fits flush with the trailing edge 109.

[0155] To ensure a smooth, continuous and separation-free flow along the bottom 104 at the bottom step (at and aft of the trailing edge 109) during the low-speed cruising in displacement mode, in sections by vertical longitudinal planes, tangents to contours of the bottom fairing 112 at the leading edge 113 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to angles of inclination of tangents to contours of the cambered planing surface 108 at the trailing edge 109.

[0156] Then, following the contours of the fairing 112 aftward, the tangents rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at the leading edge 113.

[0157] Such progression of tangents, as stipulated by the present invention, forms the bulge 114 in the forward part of the bottom fairing 112, which bulge 114 is arranged along the leading edge 113 and trailing edge 109, and protrudes below the trailing edge 109 (upward in this bottom view) in projection onto the transverse plane.

[0158] Similar to the bottom fairing 112, in the lower operational position, the leading edge 118 of the transom fairing is shaped to conform to the trailing edge 111 of the aft cambered planing surface 110, abuts upon it and fits flush with the trailing edge 111.

[0159] To ensure a smooth, continuous and separation-free flow at and behind the transom 102 (at and aft of the trailing edge 111) during the low-speed cruising in displacement mode, in sections by vertical longitudinal planes, tangents to contours of the transom fairing at the leading edge 118 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to angles of inclination of tangents to contours of the aft cambered planing surface 110 at the trailing edge 111. Following the contours of the transom fairing aftward, the tangents rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at the leading edge 118. Such progression of tangents forms the bulge 122 in the forward part of the fairing, which bulge 122 is arranged along the leading edge 118 and the trailing edge 111, and protrudes below the trailing edge 111 (upward in this bottom view) in projection onto the transverse plane.

[0160] Thus, the system of two fairings, i.e., the bottom fairing 112 and the transom fairing consisting of the front 117 and after 121 parts, located, respectively, behind the bottom step and the transom 102 and shaped to match the profiles of the cambered planing surfaces 108 and 110 of the boat 101, in the shown in FIG. 3 lower operational position, ensures the formation of a continuous smooth bottom surface, providing at low Froude numbers a smooth, continuous and separation-free flow along the bottom of boat 101, which results in low hydrodynamic resistance and the efficient operation of the boat 101 in displacement and partially transitional motion modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat 101.

[0161] At the same time, in order to ensure efficient operation of the boat 101 in its main high-speed planing mode of motion, at high Froude numbers the flow must come off the trailing edges 109 and 111 of planing surfaces 108 and 110, for which the trailing edges 109 and 111 (their back sides) must be exposed to the atmospheric air by means of the formation of substantially vertical steps along the contours of these edges. For this purpose, it is assumed that the bottom fairing 112 is made retractable and can be raised to the upper inactive position (lowered in this bottom view) by rotating its halves upward around the axes extending along their rear edges 116 (by hydraulic or electrohydraulic actuator, e.g.), so that the entire fairing 112, including its bulge 114, would be located above the trailing edges 109 (below the edges 109 in this bottom view) in projection onto the transverse plane, which position should raise the leading edge 113 and form a substantially vertical step, and this way expose the trailing edge 109 and ensure efficient operation of the boat 101 in its main high-speed planing mode.

[0162] As regards the transom fairing, in order to ensure the possibility of exposing the trailing edge 111, necessary for effective planing of the surface 110, it is assumed that the transom fairing is made both foldable and retractable.

[0163] In the FIG. 3 the transom fairing, represented in the shown lower operational position by successively composed front part 117 and after part 121, is assumed to have a smooth continuous surface and a configuration tapering from the transom 102 further aft both in the plan view, as shown in this bottom view, and with contours rising gradually from the bulge 122 to the waterline. Such a shape of the fairing ensures a smooth and separation-free flow aft of the transom 102 and results in low hydrodynamic resistance (meaning higher hydrodynamic efficiency), which leads to a decrease in the power required to propel the boat 101, a decrease in fuel consumption and a corresponding increase in cruising range when sailing in the displacement mode.

[0164] The indicated tapering aftward shape of the fairing suggests that, in projection onto the transverse plane, the after part 121 does not extend beyond the boundaries of the contour 119, and, so, can be moved forward into the cavity of the hollow front part 117 (to be completely folded and stored there) by means of, e.g., electric linear actuator.

[0165] At the same time, the front part 117 with the after part 121 folded inside its cavity can be raised up (lowered in this bottom view) to the swim platform 107, which can be accomplished, e.g., by parallelogram mechanisms suspending the front part 117 on the transom 102 and driven by electrohydraulic actuators.

[0166] Thus, the transom fairing can be folded lengthwise to the length of the front part 117 and moved up to the platform 107 to be completely covered by the platform 107 in the plan view (which makes this design compatible with the swim platform 107 and does not affect dimensions of the boat 101), while exposing the tailing edges 111.

[0167] In this way, the combined simultaneous retraction of the bottom fairing 112 (by rotating its halves around the axes at the rear edges 116), as well as the folding the after part 121 into the cavity of the hollow front part 117 and retraction of the transom fairing (pulling it up to the swim platform 107), should expose the trailing edges 109 and 111 of the forward cambered planing surface 108 and the aft cambered planing surface 110, ensuring the efficient operation of the boat 101 in its main high-speed planing mode.

[0168] The numbers 1-1 in FIG. 3 indicate a section by a plane substantially normal to the trailing edge 109.

[0169] The numbers 2-2 in FIG. 3 indicate a section by the central vertical longitudinal plane.

[0170] FIG. 4 depicts a schematic diagram illustrating the plan bottom view of a stepped hull planing boat featuring cambered planing surfaces and provided with bottom and transom fairings according to some embodiments, wherein the depicted boat represents basically the same boat as shown in FIG. 2 with the fairings shown folded and retracted for operation in the main high-speed planing mode.

[0171] The boat 101, assumed to be in planing mode, has a substantially vertical transom 102, sides 103, bottom surfaces 104, chines 105, a keel line 106 and a swim platform 107.

[0172] As a stepped hull planing boat with cambered planing surfaces, the boat 101 features a hydrodynamic system of comprising a bottom step provided with a dihedral swept-back cambered planing surface 108, as the forward planing surface of the hydrodynamic system, with its trailing edges 109 representing the edges of this bottom step, and the aft stabilizing cambered planing surface 110 with its trailing edges 111 representing the lower edges of the transom 102, wherein cambered planing surfaces 108 and 110 are arranged successively along the bottom 104 of the boat 101 and represent a single interconnected hydrodynamic planing system of the boat 101.

[0173] The boat 101 is provided with a movable relative to the hull of the boat 101 system of fairings shown retracted into their upper inactive position (corresponding to the lower position in this bottom view) in order to expose the trailing edges 109 and 111 and ensure effective operation in high-speed planing mode, which fairing system comprises a swept-back dihedral bottom fairing 112, divided breadthwise into two halves, each of which with its leading edge 113, a bulge 114, a tail section (which is assumed to be concave) and a rear edge 116 that extends along the axis of rotation of each half of the bottom fairing 112 and is substantially parallel to the swept-back trailing edge 109 (i.e., the edge of the bottom step) of the forward cambered planing surface 108, and a transom fairing shown folded and represented here by only the hollow front part 117 with its leading edge 118 and a rear edge 119, while the shape of the transom fairing features a bulge 122 and presupposes a convex tail section aft of the bulge 122.

[0174] It is assumed that the longitudinal profiling of both the front bottom 112 and transom fairings is made according to the provisions of the present invention and, in their lower operational position, ensures in the vertical longitudinal sections the equality of positive angles of inclination of tangents to the contours of the cambered planing surfaces and fairings at the abutment of the trailing and leading edges, as well as the progressive rotation of the tangents when moving aft along the contours of the fairings forming bulges 114 and 122, whereas in the embodiment of FIG. 4 the fairings are brought to their upper (lower in this bottom view) inactive position exposing the trailing edges 109 and 111 and preventing contact of the fairings with the flow along the bottom 104.

[0175] The transom fairing in its unfolded state, corresponding low-speed mode, supposed to be composed of two successively arranged lengthwise and adjoining parts (as in the embodiments of FIG. 1 and FIG. 3), and feature a tapering configuration aft from the transom 102, while because of such rearwardly tapering configuration of the fairing, the after part of the fairing does not extend beyond the boundaries of the contour 119 of the front part 117 in projection onto the transverse plain, and, so, when moved forward, the after part can be folded and placed in the hollow front part 117. Thus, in FIG. 4 it is assumed that the after part is pulled into the cavity of the hollow front part 117, is accommodated there in its folded position and, so, not visible here, which reduces the length of the transom fairing to the length of its front part 117, while the swim platform 107 completely covers the front part of the fairing 117 in the plan view.

[0176] In order to ensure efficient operation of the boat 101 in its main high-speed planing mode, the flow must come off the trailing edges 109 and 111 of planing surfaces 108 and 110, for which the trailing edges 109 and 111 (their back sides) must be exposed to the atmospheric air by means of the formation of vertical steps. For this purpose, in the FIG. 4 the bottom fairing 112 is retracted, i.e., raised to the upper (lower in this bottom view) inactive position by rotating its halves upward (down in this bottom view) around the axes extending along their rear edges 116 (by hydraulic actuators, e.g.), whereby the entire fairing 112, including its bulge 114, is located above (below in this bottom view) the trailing edges 109 in projection onto the transverse plane, preventing contact of the fairing 112 with the flow, which raised the leading edge 113 above the trailing edge 109 and formed a substantially vertical step, thereby exposing the trailing edge 109 and ensuring access of atmospheric air to the trailing edge 109 and efficient operation of the boat 101 in its main high-speed planing mode.

[0177] The transom fairing represented here by the front part 117 (assuming that the after part is folded inside its cavity) is supposed to be suspended on the transom 102 by parallelogram mechanisms driven by hydraulic or electrohydraulic actuators.

[0178] So, by pulling the parallelogram mechanisms' levers upwards using the actuators, the transom fairing was raised to its upper (lower in this bottom view) inactive position, whereby the entire transom fairing, including its bulge 122, turned out to be located above (below in this bottom view) the trailing edges 111 in projection onto the transverse plane, thus raising the leading edge 118 above the trailing edges 111 and forming a vertical step, thereby exposing the trailing edge 111 and ensuring access of atmospheric air to the trailing edge 111 and the effective operation of the boat 101 in the planing mode, while preventing the contact of the transom fairing with the flow.

[0179] In the depicted configuration of FIG. 4, where the boat 101 is equipped with a swim platform 107, the transom fairing represented by the front part 117 can be raised until its upper edge touches the lower part of the platform 107. By means of this, considering that in this embodiment the swim platform 107 totally covers the front part 117 of the transom fairing in the plan view, the compactly folded transom fairing is entirely placed under the swim platform 107, which makes this design completely compatible with the platform 107 and does not increase the dimensions of the boat 101.

[0180] Thus, this embodiment of the stepped hull boat 101 featuring cambered planing surfaces and equipped with the system of foldable retractable fairings being consistent with said cambered planing surfaces according to this invention, providing in the lower operational position of the fairings low hydrodynamic resistance in the displacement mode (i.e., high hydrodynamic efficiency), resulting in low power and fuel consumption, and a corresponding increase in the cruising range (i.e., improving the operational properties of boats), ensures in the shown upper inactive state of the fairings exposure of trailing edges 109 and 111 of planing surfaces 108 and 110 of the boat 101 and efficient operation of the boat 101 in its main high-speed planing mode.

[0181] The numbers 3-3 in FIG. 4 indicate a section by a plane substantially normal to the trailing edge 109.

[0182] The numbers 4-4 in FIG. 4 indicate a section by the central vertical longitudinal plane.

[0183] FIG. 5 depicts a schematic diagram illustrating a sectional view corresponding to section 1-1 in FIG. 3 and shows a broken-away portion of the boat at the bottom step with the bottom fairing unfolded for operation in displacement mode.

[0184] The broken-away portion of the hull of the boat 101 depicted in the FIG. 5 comprises a side 103, a piece of bottom 104, a section of the bottom step provided with a cambered planing surface 108 with its trailing edge 109 representing the edge of this bottom step, and a recess 501 behind the bottom step (i.e., aft of the trailing edge 109) formed by the substantially vertical surface of the step extending upwards from the trailing edge 109 and correspondingly recessed bottom surface, which recess 501 is used to accommodate a retractable bottom fairing 112 (its port half) with its leading edge 113, a bulge 114, a concave tail section 502 and a rear edge 116 that extends along an axis 503 of rotation of this half of the bottom fairing 112, which axis 503 is assumed to be substantially parallel to the swept-back trailing edge 109 of the forward cambered planing surface 108. In order to strengthen the structure of the fairing 112, the shell of the fairing 112 is provided with stiffening ribs represented by a stringer 504.

[0185] The fairing 112 is shown in its lower operational position corresponding to the low-speed displacement and partially transitional modes, which, in accordance with the provisions of the present invention, presupposes that:

[0186] (1) the leading edge 113 is shaped to conform to the trailing edge 109 of the forward cambered planing surface 108, abuts upon and fits flush with the trailing edge 109;

[0187] (2) the tangent to contour of the bottom fairing 112 at the leading edge 113 is inclined at a positive angle (i.e., the tangent is turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to the angle of inclination of the tangent to the contour of the cambered planing surface 108 at the trailing edge 109;

[0188] (3) following the contour of the fairing 112 aftward, the tangent rotates clockwise, i.e., its positive angle of inclination decreases and the tangent gradually comes to the zero-angle horizontal position, and then the angle becomes negative, while its modulus (absolute value) increases when moving aft, providing that in total the tangent rotates by an angle greater than the initial angle of its inclination at the leading edge 113.

[0189] Such progression of tangents forms the bulge 114 in the forward part of the bottom fairing 112, which bulge 114 is arranged along the leading edge 113 and trailing edge 109, and protrudes below the trailing edge 109 in projection onto the transverse plane.

[0190] The tail portion 502 of the fairing 112 is represented by a concave curve connecting the aft point of the bulge 114 with the rear edge 116. The angle of inclination of the tangent to such concave contour at its most forward point corresponding to the rearmost point of the bulge 114 is negative and is equal to the angle of inclination of the tangent to the contour of the bulge 114 at this rearmost point, while, when moving aft along the contour of the tail portion 502, the tangent to the contour rotates counterclockwise up to the substantially horizontal position aligned with the bottom 104.

[0191] The above described configuration of the bottom fairing 112, shaped to match the profiles of the cambered planing surface 108 following the provisions of this invention, ensures the formation of a continuous smooth bottom surface, providing at small Froude numbers a smooth, continuous and separation-free flow at the bottom step (at and aft of the trailing edge 109) and further aft along the bottom 104, which results in low hydrodynamic resistance and the efficient operation of the boat 101 in displacement and partially transitional motion modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat 101.

[0192] At the same time, in order to ensure efficient operation of the boat 101 in its main high-speed planing mode of motion, at high Froude numbers the flow must come off the trailing edge 109 of the planing surface 108, for which the trailing edge 109 (its back side) must be exposed to the atmospheric air by means of the formation of substantially vertical step along the contour of this edge. For this purpose the bottom fairing 112 is made retractable, i.e., enabling rotating each half upward around (for this half) the axis 503 by means of a hydraulic actuator 505, installed vertically and attached in the upper part to boat's hull structures, and in the lower part to the eye 506 in the stringer 504.

[0193] So that, being pulled upward by the hydraulic actuators 505, each half of fairing 112 can be raised to the upper inactive position by rotation around its axis (like 503), thereby providing that the entire fairing 112, including its bulge 114, would be located above the trailing edge 109 in projection onto the transverse plane, which position should raise the leading edge 113 and form a substantially vertical step, and this way expose the trailing edge 109 and ensure efficient planing of the forward cambered planing surface 108.

[0194] Thus, this embodiment of the bottom fairing 112 consistent with the cambered planing surface 108 according to this invention, provides in the shown lower operational position of the fairing low hydrodynamic resistance (i.e., high hydrodynamic efficiency) in displacement and partially transitional modes of motion, resulting in low power and fuel consumption, and a corresponding increase in the cruising range (i.e., improving the operational properties of the boat 101), whereas its retractability enables effective planing of the surface 108 and efficient operation of the boat 101 in the planing mode.

[0195] FIG. 6 depicts a schematic diagram illustrating a sectional view corresponding to section 3-3 in FIG. 4 and shows a broken-away portion of the boat at the bottom step with the bottom fairing retracted for operation in planing mode.

[0196] The broken-away portion of the hull of the boat 101 depicted in the FIG. 6 comprises a side 103, a piece of bottom 104, a section of the bottom step provided with a cambered planing surface 108 with its trailing edge 109 representing the edge of this bottom step, which bottom step and correspondingly recessed bottom surface aft of the step and the trailing edge 109 form a bottom recess accommodating a port half of retractable bottom fairing 112 (divided into two halves) with its leading edge 113, a bulge 114, a concave tail section 502 and a rear edge 116 that extends along the axis 503 of rotation of this half of the bottom fairing 112, which axis 503 is assumed to be substantially parallel to the swept-back trailing edge 109 (i.e., the edge of the bottom step) of the forward cambered planing surface 108. In order to strengthen the structure of the fairing 112, the shell of the fairing 112 is provided with stiffening ribs represented by a stringer 504. It is presupposed that the longitudinal profiling of the bottom fairing 112 is made in accordance with the provisions of the present invention and, in the lower operational position of the fairing 112, ensures the equality of positive angles of inclination of tangents to contours of the cambered planing surface 108 and the fairing 112 at the abutment of the trailing edge 109 and the leading edge 113, as well as the progressive rotation of the tangent, when moving aft along the contour of the fairing 112, forming the bulge 114, whereas in the embodiment of FIG. 6 the fairing 112 is brought to its upper inactive position preventing contact of the fairing 112 with the flow.

[0197] In order to be raised to the shown upper inactive position, each half of the fairing 112 is provided with a hydraulic actuator 505, installed vertically and attached at the top to the boat hull structures, and in the lower part to the eye 506 in the stringer 504.

[0198] So that in FIG. 6, the retraction of the hydraulic actuator 505 pulled the shown port half of fairing 112 upward by rotation around the axis 503 (as was done for the starboard half), as a result of which the entire fairing 112, including its bulge 114 and the leading edge 113, rose above the trailing edge 109 in projection onto the transverse plane, which exposed the trailing edge 109 and provided access of atmospheric air to the area behind the step at the edge 109 and effective planing of the cambered surface 108.

[0199] Thus, this embodiment of the retractable bottom fairing 112 according to this invention, consistent with the cambered planing surface 108 and ensuring in lower operational position of the fairing 112 low hydrodynamic resistance (i.e., high hydrodynamic efficiency) in displacement and partially transitional modes of motion, resulting in low power and fuel consumption, and a corresponding increase in the cruising range, provides in the shown retracted inactive position effective planing of the cambered planing surface 108 and efficient operation of the boat 101 in its main high-speed mode.

[0200] FIG. 7 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 1 and FIG. 3, provided with the transom fairing according to some embodiments, wherein the fairing, suspended on the transom by means of double-lever parallelogram mechanisms, is shown unfolded and lowered for operation in displacement and partially transitional modes.

[0201] In the broken-away stern portion of the hull of the boat shown in the FIG. 7, the planing boat 101 with its substantially vertical transom plane 102, sides 103, bottom surfaces 104, chines 105, the keel line 106 and the aft cambered planing surface 110 with its trailing edge 111 limited laterally by deflectors 701, is assumed to be floating on the surface of the water, while submerged up to its waterline “WL” corresponding to the stationary displacement state.

[0202] The boat 101 is provided with a movable relative to the hull of the boat 101, located aft of transom 102, foldable retractable transom fairing comprising two successively arranged along the length of the boat 101 a hollow front part 117 with its leading edge 118, a rear edge 119 and an upper skin panel 702 with its substantially horizontal upper edge 120, and an after part 121, which is movable relative to the hollow front part 117 and is in contact with the hollow front part 117 along the rear edge 119.

[0203] The foldable and retractable transom fairing composed of the front part 117 and the after part 121, features a bulge 122 and a convex tail section 123, and is shown in its lower operational position corresponding to the low-speed displacement and partially transitional modes, which, in accordance with the present invention, presupposes that:

[0204] (1) the leading edge 118 is shaped to conform to the trailing edge 111 of the aft cambered planing surface 110, abuts upon and fits flush with the trailing edge 111;

[0205] (2) in sections by vertical longitudinal planes, tangents to contours of the transom fairing (specifically, to its front part 117) at the leading edge 118 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to angles of inclination of tangents to contours of the cambered planing surface 110 at the trailing edge 111;

[0206] (3) following the contours of the transom fairing aftward, the tangents rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at the leading edge 118.

[0207] Such progression of tangents forms the bulge 122 in the forward part of the transom fairing (specifically, in the forward bottom portion of the front part 117), which bulge 122 is arranged along the leading edge 118 and the trailing edge 111, and protrudes below the trailing edge 111 in projection onto the transverse plane.

[0208] The tail section 123 of the transom fairing is formed by convex curves, smoothly rising from the aft points of the bulge 122 to the waterline “WL”. The angles of inclination of tangents to such convex contours at their most forward points corresponding to the rearmost points of the bulge 122 are negative and are equal to the angles of inclination of the tangents to the contours of the bulge 122 at their rearmost points, while, when moving aft along the contours of the tail portion 123, the tangents to the contours continue to rotate clockwise (i.e., the moduli of the negative angles continue to rise).

[0209] As a result the transom fairing is assumed to have a smooth continuous surface and a configuration tapering further aft from the transom 102 both in the plan view and in the shown side view, where the contours gradually rise from the bulge 122 to the waterline “WL”, which is optimal for displacement vessels sailing at low Froude numbers.

[0210] Such configuration of the transom fairing, shaped to match the profiles of the cambered planing surface 110 following the provisions of this invention and tapering further aft from the transom 102 and the bulge 122, ensures the formation of a continuous smooth bottom surface aft of the transom 102, providing at low Froude numbers a smooth, continuous and separation-free flow at and behind the transom 102 (aft of the trailing edge 111), which results in low hydrodynamic resistance and the efficient operation of the boat 101 in displacement and partially transitional modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat 101.

[0211] The tapered aftward shape of the transom fairing suggests that the after part 121 does not extend beyond the boundaries of the contour 119 in projection onto the transverse plane, which makes it possible to move the after part 121 forward, fold it and store it in the cavity of the hollow front part 117. Such folding can be carried out by not shown in the FIG. 7 longitudinally arranged electric linear actuators, e.g.

[0212] The hull of the boat 101 is also equipped with a swim platform 107, mounted on the transom 102, extending aftward of the transom 102 and above the waterline “WL”, so that in this mode the substantially horizontal upper edge 120 of the transom fairing is located below the platform 107 and above the waterline “WL”, and the platform 107 partially covers the fairing in the plan view, while completely covering the front part 117. In the embodiment shown in the FIG. 7, the fairing (specifically, its front part 117) is suspended on the transom 102 by means of double-lever parallelogram mechanisms schematically shown in the conventional cutout 703 in the side of the front part 117.

[0213] The parallelogram mechanisms comprise the levers 704 arranged presumably in pairs on both sides of the front part 117 and shown inclined downwards to ensure the lower operational position of the transom fairing, the front hinges 705 of the levers 704, fixed on the transom 102 one above the other vertically, and the rear hinges 706 of the levers 704, assumed to be fixed one above the other vertically on the sides and inside the shell of the front part 117, and are driven by two vertical hydraulic actuators 505, located each on its side of the front part 117 and attached at their tops from below to the swim platform 107, as shown in the conventional cutout 708 in the side part of the swim platform 107, and in the lower part to the levers 704 through the eyes 707.

[0214] The axes of rotation of hinges 705 and 706 are substantially normal to the boat's center plane, so that in the case of retraction of hydraulic actuators 505, the parallelogram levers 704 will rotate clockwise around the axes of the front hinges 705, when viewed from the starboard side of the boat, from the position in which the levers 704 are inclined as shown downwards relative to the front hinges 705, to their upper position, in which the levers 704 will be inclined upwards relative to the front hinges 705, resulting in raising the transom fairing (meaning the front part 117 with the after part 121 folded inside) from its lower operational position to the upper inactive position.

[0215] Thus, the embodiment of the transom fairing shown in FIG. 7 provides the after part of the boat 101 with smooth and separation-free flow at and aft of the trailing edge 111, given to it by the configuration of the fairing (featuring abutting edge 118, the bulge 122 and progression of tangents to contours of the fairing according this invention), consistent with the aft cambered planing surface 110, and rounded stern formations, optimal for displacement sailing at low Froude numbers, which result in low hydrodynamic resistance in displacement mode (meaning higher efficiency) leading to a decrease in the power required to propel the boat 101, a decrease in fuel consumption and a corresponding increase in cruising range when sailing in the displacement mode.

[0216] At the same time, the foldability of this transom fairing, provided by sectioning the fairing with the after part 121 movable relative to the front part 117, as well as the ability of the compactly folded fairing to be lifted (retracted) using parallelogram mechanisms, allow for efficient operation of the boat 101 in the main high-speed planing mode.

[0217] FIG. 8 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 2 and FIG. 4, provided with a transom fairing according to some embodiments, wherein the fairing, suspended on the transom by means of double-lever parallelogram mechanisms, is shown folded and raised to its inactive position, ensuring effective operation of the boat in the main planing mode.

[0218] In the broken-away stern portion of the hull of the boat shown in the FIG. 8, the planing boat 101 with its substantially vertical transom plane 102, sides 103, bottom surfaces 104, chines 105, the keel line 106 and the aft cambered planing surface 110 with its trailing edge 111 limited laterally by deflectors 701, is assumed to be moving in its main high-speed planing mode.

[0219] The boat 101 is provided with a movable relative the hull of the boat 101, located aft of transom 102, foldable retractable transom fairing comprising the hollow front part 117 with its the leading edge 118 adjacent to the transom 102, the rear edge 119, and the upper skin panel 702 of the shell of the hollow front part 117 with its upper edge 120, and the after part not extending beyond the contour of the edge 119 in projection onto the transverse plane, which made it possible to move the after part forward and fold it inside the cavity of the hollow front part 117, so that the shown fairing is presumed to be folded and only the front part 117 of the folded fairing is visible in the FIG. 8.

[0220] It is presupposed that the profiling of the transom fairing (represented here by the front part 117) is made in accordance with the present invention and, in the lower operational position of the fairing, ensures the equality of positive angles of inclination of tangents to contours of the cambered planing surface 110 and the fairing at the abutment of the trailing edge 111 and the leading edge 118, as well as the progressive rotation of tangents when moving aft along the contour of the fairing forming the bulge 122 and the convex tail 123, whereas in the embodiment of FIG. 8 the transom fairing is brought to its upper inactive position preventing contact of the fairing with the flow.

[0221] In order to provide efficient, low-drag motion of the boat 101 in its primary high-speed planing mode, the flow of water must come off the trailing edge 111, for which the trailing edge 111 must be exposed by means of a transom step 201 formed by the surface of the transom 102 extending substantially vertically from the trailing edge 111. This is achieved by raising the folded transom fairing, i.e., raising the front hollow part 117 adjacent to the transom 102 with the after part folded inside, from the lower operational position of the front part 117 (covering from behind the trailing edge 111 in the displacement mode) to the position somewhat above the edge 111, as shown in the FIG. 8, which exposes the edge 111 and forms the transom step 201 extending from the trailing edge 111 up to the raised leading edge 118 of the front part 117.

[0222] In the embodiment of FIG. 8, wherein the boat 101 is equipped with a swim platform 107 completely covering the front part 117 in the plan view, the transom fairing (represented by the front part 117) is raised up to the position where its upper edge 120 touches the lower edge of the platform 107, while the compactly folded fairing is completely placed under the swim platform 107, which makes this design perfectly compatible with the swim platform 107 and does not increase the dimensions of the boat 101.

[0223] To carry out said lifting of the fairing, in the embodiment shown in the FIG. 8, the fairing (specifically its front part 117) is suspended on the transom 102 by means of double-lever parallelogram mechanisms schematically shown in the conventional cutout 703 in the side of the front part 117.

[0224] The parallelogram mechanisms comprise the levers 704 arranged presumably in pairs on both sides of the front part 117 and shown inclined upwards to ensure the high inactive position of the fairing, the front hinges 705 of the levers 704, fixed on the transom 102 one above the other vertically, and the rear hinges 706 of the levers 704, supposed to be fixed one above the other vertically on the sides and inside the shell of the front part 117, and are driven by two vertical hydraulic actuators 505 (shown retracted), located each on its side of the front part 117 and attached at their tops from below to the swim platform 107, and in the lower part to the levers 704 through the eyes 707, as shown in the conventional cutout 708 in the side part of the swim platform 107. The axes of rotation of hinges 705 and 706 are substantially normal to the boat's center plane, so that as the result of the retraction of the actuators 505, the parallelogram levers 704 rotated clockwise around the axes of the front hinges 705, when viewed from the starboard side of the boat, from the position in which the levers 704 were inclined downwards relative to the front hinges 705, to their upper position, in which the levers 704 are inclined upwards relative to the front hinges 705, resulting in the transom fairing (i.e., the front part 117 with the after part folded inside) has risen from its lower operational position to the upper inactive position, ensuring efficient operation in planing mode and a compact configuration of the boat 101 when at high speed or rest.

[0225] Thus, the embodiment of the transom fairing shown in FIG. 8, made in accordance with the present invention and providing the consistence of its shape with the aft cambered planing surface 110, a smooth, continuous and separation-free flow behind the trailing edge 111, and the effective cruising of the boat 101 in displacement and partially transitional modes, enabled, with the help of double-lever parallelogram mechanisms, to pull the transom fairing to the upper inactive position, thereby ensuring the effective planing of the surface 110 and operation of the boat 101 in its main high-speed planing mode, while maintaining minimal dimensions when moving at high speed and at rest.

[0226] FIG. 9 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 1 and FIG. 3, provided with the transom fairing according to some embodiments, wherein the fairing, unfolded and lowered for operation in displacement mode, is shown in a sectional view corresponding to section 2-2 in FIG. 3.

[0227] In the broken-away stern portion of the hull of the boat shown in the FIG. 9, the planing boat 101 with its substantially vertical transom plane 102, sides 103, bottom surfaces 104, chines 105, the keel line 106 and the aft cambered planing surface 110 with its trailing edge 111 limited laterally by deflectors 701, is assumed to be floating on the surface of the water, while submerged up to its waterline “WL” corresponding to the stationary displacement state.

[0228] The boat 101 is provided with a movable relative the hull of the boat 101, located aft of transom 102, foldable and retractable transom fairing (shown with shaded shells in the center plane sectional view corresponding to section 2-2 in FIG. 3) comprising two successively arranged along the length of the boat 101 a hollow front part 117 with its leading edge 118, a rear edge 119 and an upper skin panel 702 with its substantially horizontal upper edge 120, and an after part 121, which is movable relative to the hollow front part 117 and is in contact with the front part 117 along the rear edge 119.

[0229] The foldable and retractable transom fairing, composed of the front part 117 and the after part 121, features a bulge 122 and a convex tail section 123, and is shown in its lower operational position corresponding to the low-speed displacement and partially transitional modes, which, in accordance with the present invention, presupposes that:

[0230] (1) the leading edge 118 is shaped to conform to the trailing edge 111 of the aft cambered planing surface 110, abuts upon and fits flush with the trailing edge 111;

[0231] (2) in sections by vertical longitudinal planes, tangents to contours of the transom fairing (specifically, to its front part 117) at the leading edge 118 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to angles of inclination of tangents to contours of the cambered planing surface 110 at the trailing edge 111;

[0232] (3) following the contours of the transom fairing aftward, the tangents rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at the leading edge 118.

[0233] Such progression of tangents forms the bulge 122 in the forward part of the transom fairing (specifically, in the forward bottom portion of the front part 117), which bulge 122 is arranged along the leading edge 118 and the trailing edge 111, and protrudes below the trailing edge 111 in projection onto the transverse plane.

[0234] The tail section 123 of the transom fairing is formed by convex curves, smoothly rising from the aft points of the bulge 122 to the waterline “WL”. The angles of inclination of tangents to such concave contours at their most forward points corresponding to the rearmost points of the bulge 122 are negative and are equal to the angles of inclination of the tangents to the contours of the bulge 122 at their rearmost points, while, when moving aft along the contours of the tail portion 123, the tangents to the contours continue to rotate clockwise (i.e., the moduli of the negative angles continue to rise).

[0235] As a result the transom fairing is assumed to have a smooth continuous surface and a configuration tapering further aft from the transom 102 both in the plan view and in the shown side view, where the contours gradually rise from the bulge 122 to the waterline “WL”, which is optimal for displacement vessels sailing at low Froude numbers.

[0236] The above described configuration of the transom fairing, shaped to match the profiles of the cambered planing surface 110 following the provisions of this invention and tapering further aft from the transom 102, ensures the formation of a continuous smooth bottom surface aft of the transom 102, providing at low Froude numbers a smooth, continuous and separation-free flow at and behind the transom 102 (aft of the trailing edge 111), which results in low hydrodynamic resistance and the efficient operation of the boat 101 in displacement and partially transitional modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat 101.

[0237] The tapered aftward shape of the transom fairing suggests that the after part 121 does not extend beyond the boundaries of the contour 119 in projection onto the transverse plane, which makes it possible to move the after part 121 forward, fold it and store it in the cavity of the hollow front part 117.

[0238] For this purpose the front part 117 is provided with longitudinal inverted T-shaped rails 901 attached from below to the upper skin panel 702 of the shell of the hollow front part 117, along which inverted T-slot sliders 902 of the after part 121 can slide forward until the after part 121 should stop in its extreme forward position, ensuring the complete placement of the after part 121 inside the cavity of the hollow front part 117.

[0239] To perform such folding, the fairing is equipped with a longitudinally arranged and centrally located electric linear actuator, which provides longitudinal movement of the after part 121 and comprises the linear drive screw 903, supported by the front end support 904 (combined with drive) and rear end support 905, secured from below to the upper skin panel 702 in the front and rear extremities of the front part 117, respectively, and the ball nut 906 of the drive attached to the front end of the after part 121 by brackets (not shown). The rotation of the linear drive screw 903, provided by the electric motor 907 through the drive of the front end support 904, leads to the longitudinal movement of the ball nut 906, which pulls forward or pushes back the after part 121.

[0240] So that, in the shown operational position of unfolded fairing, the ball nut 906 is brought along the linear drive screw 903 to the rearmost position of the linear actuator.

[0241] The hull of the boat 101 is also equipped with a swim platform 107, mounted on the transom 102, extending aftward of the transom 102 and above the waterline “WL”, so that in this mode the substantially horizontal upper edge 120 of the transom fairing is located below the platform 107 and above the waterline “WL”, and the platform 107 partially covers the fairing in the plan view, while completely covering the front part 117. In the embodiment shown in the FIG. 9, the fairing (specifically its front part 117) is suspended from below the swim platform 107 by means of vertical hydraulic actuators 505 shown in the conventional breakout 908 in the side part of the swim platform 107.

[0242] Retraction of hydraulic actuators 505, arranged assumably in pairs on both sides of the front part 117, leads to vertical lifting of the fairing (i.e. its front part 117 with the after part 121 folded inside) and its transfer to the upper inactive position, which ensures efficient operation of the boat in planing mode and minimal dimensions when at rest.

[0243] To ensure a tight fit of the leading edge 118 of the front part 117 to the transom 102, the edge 118 and the plane of the transom 102 can be provided with vertical rail slides (not shown), which would hold the front part 117 in constant contact with the transom 102 during lifting and lowering of the transom fairing.

[0244] Thus, the embodiment of the transom fairing shown in FIG. 9, made in accordance with the present invention, provides the consistence of its shape with the aft cambered planing surface 110, and, so, a smooth, continuous and separation-free flow behind the trailing edge 111, and effective cruising of the boat 101 in displacement and partially transitional modes, while it is capable of folding to the length of the front part 117 (using the electric linear actuator) and retracting up to the swim platform 107 (to be completely covered by the swim platform 107) using vertical hydraulic actuators, thereby ensuring efficient operation of the boat 101 in its main high-speed planing mode of movement.

[0245] The letters A-A designate the view of fairing rearwards from the transom 102.

[0246] FIG. 10 depicts a schematic diagram illustrating the side elevation view of the aft part of a stepped hull planing boat featuring cambered planing surfaces, basically similar to boats shown in FIG. 2 and FIG. 4, provided with the transom fairing according to some embodiments, wherein the fairing, folded and raised for operation in planing mode, is shown in a sectional view corresponding to section 4-4 in FIG. 4.

[0247] In the broken-away stern portion of the hull of the boat shown in the FIG. 10, the planing boat 101 with its substantially vertical transom plane 102, sides 103, bottom surfaces 104, chines 105, the keel line 106 and the aft cambered planing surface 110 with its trailing edge 111 limited laterally by deflectors 701, is assumed to be moving in its main high-speed planing mode.

[0248] The boat 101 is provided with a movable relative the hull of the boat 101 and located aft of transom 102 foldable and retractable transom fairing, shown in the folded upper inactive position in a sectional view corresponding to the section 4-4 in FIG. 4 and featuring hatched center plane sections of fairing shells.

[0249] The fairing, which shells, in order to not clutter the view of its foldable and retractable design, are shown not reinforced with internal frames and stringers, comprises the hollow front part 117 with its the leading edge 118 adjacent to the transom 102, the rear edge 119, and the upper skin panel 702 with its upper edge 120, and the after part 121.

[0250] It is presupposed that, in the lower operational position of the transom fairing, the profiling of the compound two-part fairing corresponds to the present invention and ensures the equality of angles of inclination of tangents to contours of the cambered planing surface 110 and the fairing at the abutment of the trailing edge 111 and the leading edge 118, as well as the progressive rotation of tangents when moving aft along the contour of the fairing, forming the bulge 122 and the convex tail 123, whereas in FIG. 10 the transom fairing is shown brought to its upper inactive position preventing contact of the transom fairing with the flow and with disconnected front 117 and rear 121 parts. Due to the assumed tapering aft configuration of the fairing, the after part 121 does not extend beyond the contour of the edge 119 in projection onto the transverse plane, which made it possible to move the after part 121 forward and fold it inside the cavity of the hollow front part 117 (their shell sections are shaded), so that the shown fairing is presumed to be folded with the after part 121 accommodated inside the front part 117. For the purpose of folding, the front part 117 is provided with longitudinal inverted T-shaped rails (not visible here) attached from below to the upper panel 702 of the shell of the hollow front part 117, along which inverted T-slot sliders 902 of the after part 121 slid forward until the after part 121 stopped in its extreme forward position, ensuring the complete placement of the after part 121 inside the cavity of the hollow front part 117.

[0251] To perform such folding, the fairing is equipped with a longitudinally arranged and centrally located electric linear actuator, which provides longitudinal movement of the after part 121 and comprises the linear drive screw 903, supported by the front end support 904 (combined with drive) and rear end support 905, secured from below to the upper panel 702 in the front and rear of the front part 117, respectively, and the ball nut 906 of the drive attached to the front end of the after part 121 by brackets (not shown).

[0252] The rotation of the linear drive screw 903, provided by the electric motor 907 through the drive of the front end support 904, leads to the longitudinal movement of the ball nut 906, which pulls forward or pushes back the after part 121. So that, in the shown in FIG. 10 upper inactive position of folded and retracted fairing, the ball nut 906 is brought along the linear drive screw 903 to the most forward position of the linear actuator.

[0253] In order to provide efficient, low-drag motion of the boat 101 in its primary high-speed planing mode, the flow of water must come off the trailing edge 111, for which the trailing edge 111 must be exposed by means of a transom step 201 formed by the surface of the transom 102 extending substantially vertically from the trailing edge 111. This is achieved by raising the folded transom fairing, i.e. raising the front hollow part 117 adjacent to the transom 102 with the after part 121 folded inside, from the lower operational position of the front part 117 (covering from behind the trailing edge 111 in the displacement mode) to the position somewhat above the edge 111, as shown in the FIG. 10, which exposes the edge 111 and forms the transom step 201 extending from the trailing edge 111 up to the raised leading edge 118 of the front part 117.

[0254] In the embodiment of FIG. 10, wherein the boat 101 is equipped with a swim platform 107 completely covering the front part 117 in the plan view, the transom fairing (the front part 117 with the after part 121 placed inside) is raised up to the position where its upper edge 120 contacts the platform 107 from below, while the compactly folded fairing is completely placed under the swim platform 107, which makes this design compatible with the swim platform 107 and does not increase the dimensions of the boat 101.

[0255] To accomplish such retraction, in the embodiment shown in the FIG. 10, the transom fairing (specifically its front part 117) is suspended from below the swim platform 107 by means of vertical hydraulic actuators 505 shown in the conventional breakout 908 in the side part of the swim platform 107. Retraction of actuators 505, arranged presumably in pairs on both sides of the front part 117, has resulted in vertical lifting of the fairing (i.e. its front part 117 with the after part 121 folded inside) and its transfer to the upper inactive position, which ensures efficient operation of the boat 101 in planing mode and minimal dimensions when moving at high speed and at rest.

[0256] To ensure a tight fit of the leading edge 118 of the front part 117 to the transom 102, the edge 118 and the plane of the transom 102 can be provided with vertical guides, e.g., rail slides (not shown), which would keep the front part 117 in constant contact with the transom 102 during the raising and lowering of the fairing.

[0257] Thus, the embodiment of the transom fairing shown in FIG. 10, made in accordance with the present invention and providing the consistence of its shape with the aft cambered planing surface 110, a smooth, continuous and separation-free flow behind the trailing edge 111, and the effective cruising of the boat 101 in displacement and partially transitional modes, made it possible, with the help of the electric linear actuator and vertically arranged hydraulic actuators, to fold the transom fairing to the length of the front part 117 and pull the transom fairing to the upper inactive position, thereby ensuring the effective operation of the boat 101 in its main high-speed planing mode, while maintaining minimal dimensions when moving at high speed and at rest.

[0258] FIG. 11 depicts a schematic diagram illustrating a view of the fairing when looking aft from the transom, corresponding to the view designated by the letters A-A in FIG. 9, in which the fairing is shown unfolded and lowered for operation in displacement mode.

[0259] The transom fairing, which shells, in order to not clutter the view of its foldable and retractable design, are shown in the embodiment not reinforced with internal frames and stringers, comprises two successively arranged lengthwise portions: the hollow front part 117 and the after part 121, which are in contact along a longitudinal cylindrical surface corresponding to the peripheral contour of the rear edge of the front part 117 and visible here as contour 1101, while the hollow front part 117 has a peripheral leading edge 118 shaped to conform to the lower peripheral edge of the boat's transom and supposed to be abutting the trailing edge of the aft cambered planing surface.

[0260] The shells of the transom fairing feature protruding chines 1102 and deflectors 1103 tapering astern and representing continuations of the chines and deflectors of the boat hull and, actually, the aft fairings of these hull protrusions.

[0261] The shell of the front part 117 is covered by the upper skin panel 702 forming the upper edge 120 of the front part 117.

[0262] As can be seen from FIG. 11, the after part 121 does not extend beyond the boundaries of the contour 1101, which makes it possible to move the after part 121 forward, fold it and store it inside the hollow front part 117.

[0263] For this purpose the front part 117 is provided with longitudinal inverted T-shaped rails 901 attached from below to the upper skin panel 702, and the after part 121 is provided with longitudinal inverted T-slot sliders 902 structurally connected to the shell of the after part 121 by vertical longitudinal supports 1104, so that the sliders 902 of the after part 121 can slide along the rails 901 forward until the after part 121 stops in the extreme forward position, ensuring the complete placement of the after part 121 inside the cavity of the hollow front part 117.

[0264] To perform such folding, the fairing is equipped with a longitudinally arranged and centrally located electric linear actuator, represented here by the only visible in the FIG. 11 front end support 904, which is secured from below to the upper skin panel 702 at the forward extremity of the front part 117 and assumed to be combined with a drive.

[0265] The longitudinal thrust of the linear actuator is transmitted to the after part 121, and more specifically to the forward part of the inverted T-slot sliders 902 of the after part 121, via brackets 1105, so that if pulled by the linear actuator from the shown rearmost unfolded position, the after part 121 will move (slide along rails 901) forward up to complete placement and folding in the cavity of the hollow front part 117.

[0266] In the embodiment shown in the FIG. 11, the fairing (specifically its front part 117) is suspended from below the swim platform 107 (the cross-section of which is shaded) by means of vertical hydraulic actuators 505, arranged assumably in pairs on both sides of the front part 117 and released to provide the lower operational position of the fairing.

[0267] If retracted, the actuators 505 will lift the fairing (i.e., its front part 117 with the after part 121 folded inside) vertically and transfer it to the upper inactive position, which ensures efficient operation of the boat in planing mode and compactness at high speed and rest. In the shown lower operational position of the transom fairing, the profiling of the compound two-part fairing corresponds to the present invention and ensures the equality of angles of inclination of tangents to contours of the aft cambered planing surface and the fairing at the abutment of the trailing edge of the aft cambered planing surface and the leading edge 118, as well as the progressive rotation of tangents when moving aft along the contours of the fairing, forming the bulge 122 and the convex tail.

[0268] Thus, the embodiment of the transom fairing shown in FIG. 11, made in accordance with the present invention, provides the consistence of its shape with the aft cambered planing surface, a smooth, continuous and separation-free flow behind the trailing edge of the aft cambered planing surface, and the effective cruising of the boat 101 in displacement and partially transitional modes, while enabling, with the help of the electric linear actuator and vertically arranged hydraulic actuators, to be folded to the length of the front part 117 and pulled to the upper inactive position, thereby ensuring the effective operation of the boat 101 in its main high-speed planing mode, while maintaining minimal dimensions when moving at high speed and at rest.

[0269] FIG. 12 depicts a schematic diagram illustrating a perspective view of a half of the bottom fairing according to some embodiments, wherein the shell of the fairing featuring convex tail section is reinforced with stringers.

[0270] The half of the swept-back and installed at some angle of deadrise bottom fairing 112, supposed to be accommodated in the starboard part of the bottom recess behind the bottom step and shown in perspective corresponding to the view from the central plane of the boat towards the starboard side, comprises a leading edge 113 and a rear edge 116, while the shell of the fairing 112 features a curvature forming a bulge 114 in the front part and a convex tail part 1201 between the bulge 114 and the rear edge 116.

[0271] The shape and profiling of the fairing 112 are made in accordance with the provisions of the present invention, and thus, in the lower operational position of the fairing 112 corresponding to the low-speed displacement and transitional modes, it assumes that:

[0272] (1) the leading edge 113 is shaped to conform to the trailing edge of the forward cambered planing surface, abuts upon and fits flush with said trailing edge;

[0273] (2) in sections by vertical longitudinal planes, tangents to contours of the bottom fairing 112 at the leading edge 113 are inclined at a positive angle (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat) being equal to angles of inclination of tangents to contours of the forward cambered planing surface at its trailing edge;

[0274] (3) in sections by vertical longitudinal planes, following contours of the fairing 112 aftward, the tangents to contours rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving further aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at the leading edge 113.

[0275] Such progression of tangents forms the bulge 114 in the forward part of the bottom fairing 112, which bulge 114 is arranged along the leading edge 113 and said trailing edge, and protrudes below the trailing edge in projection onto the transverse plane.

[0276] The tail section 1201 of the bottom fairing 112 is formed by convex curves, smoothly rising from the aft points of the bulge 114 to the rear edge 116. The angles of inclination of tangents to such convex contours at their most forward points corresponding to the rearmost points of the bulge 114 are negative and are equal to the angles of inclination of the tangents to the contours of the bulge 114 at their rearmost points, while, when moving aft along the contours of the tail portion 1201, the tangents to the contours continue to rotate clockwise (i.e., the moduli of the negative angles continue to rise).

[0277] The above described configuration of the bottom fairing 112, shaped to match the profiles of the forward cambered planing surface following the provisions of this invention, ensures the formation of a continuous smooth bottom surface, providing at low Froude numbers a smooth, continuous and separation-free flow at and aft of the trailing edge of the forward cambered planing surface and further aft along the bottom, which results in low hydrodynamic resistance and the efficient operation of the boat in displacement and partially transitional motion modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat.

[0278] The shell of the fairing 112 is reinforced with stiffening ribs (stringers) 504, while the enlarged stringer 1202 on the side edge of the fairing 112 serves as an end cover, preventing water from flowing into the cavity between the lowered to operational position fairing 112 and the bottom recess when the boat is moving in displacement and transitional modes (which flowing can lead to an increase in hydrodynamic resistance).

[0279] The rear ends of the stringers 504 are provided with knuckles 1203 for hinges ensuring rotation of this half of bottom fairing 112 around an axis parallel to the rear edge 116. The matching knuckles for the knuckles 1203 are to be fixed on bottom structures located at the aft part of the bottom recess used to accommodate the fairing 112.

[0280] In order to ensure efficient operation of the boat in its main high-speed planing mode, the flow must come off the trailing edge of the forward planing surface, for which the trailing edge (its back side) must be exposed to the atmospheric air by means of the formation of substantially vertical step along the contour of this edge. For this purpose the bottom fairing 112 is made retractable by means of the ability to rotate on hinges of knuckles 1203 around the axis being substantially parallel to the rear edge 116 and equipment with a hydraulic actuator, installed vertically and attached in the upper part to boat's hull structures, and in the lower part to the eye 506 in one of the stringers 504.

[0281] So that, being pulled upward by the hydraulic actuator, the bottom fairing 112 can be raised to the upper inactive position by rotation around said axis, providing that the entire fairing 112, including its bulge 114, would be located above the trailing edge of the forward cambered planing surface in projection onto the transverse plane, which position should raise the leading edge 113 and form a substantially vertical step, and this way expose the trailing edge of the forward cambered planing surface and ensure efficient operation of the boat in its main high-speed planing mode.

[0282] Thus, this embodiment of the bottom fairing 112 consistent with the bottom cambered planing surface according to this invention, provides, in the lower operational position of the bottom fairing, low hydrodynamic resistance (i.e., high hydrodynamic efficiency) in displacement and partially transitional modes of motion, resulting in low power and fuel consumption, and a corresponding increase in the cruising range (i.e., improving the operational properties of the boat), whereas its retractability enables efficient operation of the boat in the planing mode at high Froude numbers.

[0283] FIG. 13 depicts a schematic diagram illustrating a perspective aft bottom view of a stepped hull planing boat featuring cambered planing surfaces, provided with bottom and transom fairings according to some embodiments, wherein the fairings are shown lowered, unfolded and deployed for operation in displacement and transitional modes.

[0284] The planing boat 101, presumably cruising in displacement or transitional mode and shown in an upside-down position, has a substantially vertical transom 102, sides 103, dihedral bottom surfaces 104, chines 105, a keel line 106 and a swim platform 107.

[0285] As a stepped hull planing boat with cambered planing surfaces, the shown boat 101 features a hydrodynamic system comprising a bottom step provided with a dihedral and swept-back cambered planing surface 108, as the forward planing surface, with its trailing edges 109 representing the edges of the bottom step, and a dihedral aft stabilizing cambered planing surface 110 with its trailing edges 111, representing the lower edges of the transom 102, and lateral deflectors 701, wherein cambered planing surfaces 108 and 110 are arranged successively along the bottom 104 of the boat 101 and represent a single interconnected hydrodynamic planing system of the boat 101.

[0286] In this embodiment the forward planing surface 108 extends laterally beyond the width of the chines 105 by means of external projections 1301 representing profiled continuations of the planing surface 108 outside the chines 105, which provides the planing surface 108 with a higher aspect ratio (and, so, higher hydrodynamic efficiency), while the streamlined longitudinal profiles of the projections 1301 do not have a significant effect on the hydrodynamic resistance of the boat 101 in displacement mode. The boat 101 is provided with a system of movable relative to the hull of the boat 101 retractable fairings comprising a swept-back dihedral bottom fairing 112, divided breadthwise into two halves symmetrical relative to the central plane of the boat 101, and a transom fairing, located aft of the transom 102 under the swim platform 107 and consisting of a hollow front part 117 and an after part 121 movable relative to the front part 117, while, in the shown lower (upper in this inverted view) operational position corresponding to displacement and partially transitional modes, the hollow front part 117 and the after part 121 are adjoined and arranged successively along the length of the boat 101 forming a continuous smooth surface of the transom fairing.

[0287] Each half of the bottom fairing 112 features a leading edge 113, a bulge 114, a convex tail section 1201, an end cover 1202 and a rear edge 116 that extends along the axis of rotation of the bottom fairing 112 and is substantially parallel to the swept-back trailing edge 109 of the forward cambered planing surface 108 and, so, the edge of the step.

[0288] The hollow front part 117 of the transom fairing has a leading edge 118, a rear edge 119 an upper edge 120, while the shape of the transom fairing in general features a bulge 122, a convex tail section 123 and protruding chines 1102 and deflectors 1103 tapering astern and representing a continuation of the chines 105 and deflectors 701 of the hull of the boat 101, so, they are, actually, the aft fairings for these hull protrusions. The shape and profiling of the bottom 112 and transom fairings are made in accordance with the provisions of the present invention, and thus, in the shown lower (upper in this upside down view) operational position of the fairings corresponding to the low-speed displacement and partially transitional modes, it assumes that:

[0289] (1) the leading edges 113 and 118 of the bottom fairing 112 and the transom fairing are shaped to conform to the trailing edges 109 of the forward cambered planing surface 108 and 111 of the aft cambered planing surface 110, abut upon and fit flush with the trailing edges 109 and 111, respectively;

[0290] (2) in sections by vertical longitudinal planes, tangents to contours of the bottom fairing 112 at leading edges 113 and the transom fairing at leading edges 118 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to the angles of inclination of tangents to corresponding same-plane contours of the forward cambered planing surface 108 at its trailing edges 109 and the aft cambered planing surface 110 at its trailing edges 111, respectively;

[0291] (3) in sections by vertical longitudinal planes, following the contours of the bottom fairing 112 and the transom fairing aftward, the tangents to said contours rotate clockwise, i.e., their positive angles of inclination decrease and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at leading edges 113 and 118.

[0292] Such progression of tangents forms the bulge 114 in the forward part of the bottom fairing 112 and the bulge 122 in the forward part of the transom fairing, which bulges 114 and 122 are arranged along the leading edges 113 and 118 (and, so, trailing edges 109 and 111) and protrude below the trailing edges 109 and 111 in projection onto the transverse plane, respectively.

[0293] The tail portions: 1201 of the bottom fairing 112 and 123 of the transom fairing, are represented in sections by vertical longitudinal planes with convex curves behind the rearmost points of the bulges 114 and 122, while, at the points of connection, the angles of inclination of tangents to these convex curves and the tangents to the contours of the bulges 114 and 122 are equal, which means that, following the contours aftward, the tangents to the contours of the sections of the fairings aft of the bulges 114 and 122 continue to gradually rotate clockwise, forming convex tail shapes of the fairings.

[0294] Thus, the system of two fairings, i.e., the bottom fairing 112 and the transom fairing consisting of the front part 117 and after part 121, located, respectively, behind the bottom step and the transom 102 and shaped to match the profiles of the cambered planing surfaces 108 and 110 of the boat 101, in the shown lower operational position, ensures the formation of a continuous smooth bottom surface, providing at low Froude numbers a smooth, continuous and separation-free flow along the bottom of boat 101, which results in low hydrodynamic resistance and the efficient operation of the boat 101 in displacement and partially transitional motion modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat 101.

[0295] At the same time, in order to ensure efficient operation of the boat 101 in its main high-speed planing mode of motion, at high Froude numbers the flow must come off the trailing edges 109 and 111 of planing surfaces 108 and 110, for which the trailing edges 109 and 111 (their back sides) must be exposed to the atmospheric air by means of the formation of substantially vertical steps along the contours of these edges. For this purpose, it is assumed that the bottom 112 and transom fairings are made retractable and can be raised to the upper inactive position to expose said trailing edges.

[0296] The bottom fairing 112 can be rotated around the axis extending along the rear edge 116, so that, being turned upward (by hydraulic or electrohydraulic actuator, e.g.), the entire fairing 112, including its bulge 114, would be located above (below in this inverted view) the trailing edges 109 in projection onto the transverse plane, which position should raise the leading edge 113 and form a substantially vertical step, and this way expose the trailing edge 109 and ensure efficient planing of the cambered surface 108. As regards the transom fairing, in order to ensure the possibility of exposing the trailing edge 111, necessary for effective planing of the surface 110, it is assumed that the transom fairing is made both foldable and retractable.

[0297] In the FIG. 13 the transom fairing, represented in the shown lower operational position by successively composed front part 117 and after part 121, is assumed to have a smooth continuous surface and a configuration tapering aftward from the transom 102. Such a shape of the fairing (which is optimal for small Froude numbers) ensures a smooth and separation-free flow aft of the transom 102 and results in low hydrodynamic resistance (meaning higher hydrodynamic efficiency), which leads to a decrease in the power required to propel the boat 101, a decrease in fuel consumption and a corresponding increase in cruising range when sailing in the displacement mode.

[0298] The indicated tapering aftward shape of the fairing suggests that, in projection onto the transverse plane, the after part 121 does not extend beyond the boundaries of the contour 119, and, so, can be moved forward into the cavity of the hollow front part 117 (to be completely folded and stored there) by means of, e.g., electric linear actuator.

[0299] At the same time, the swim platform 107 of the boat 101, mounted on the transom 102, extends aftward of the transom 102 and above the upper edge 120 of the front part of fairing 117, so that the front part 117 with the after part 121 folded inside its cavity can be raised upward till the upper edge 120 contacts the lower edge of the swim platform 107, which supposed to be carried out by parallelogram mechanisms suspending the front part 117 on the transom 102 and driven, e.g., by electrohydraulic actuators. In this case, the leading edge 118 (and the bulge 122) would have to rise above the trailing edge 111 and expose a vertical surface of the lower part of the transom 102 and thus form a vertical step exposing the trailing edge 111, providing access of atmospheric air to the edge 111 and effective planing of the aft cambered stabilizing surface 110.

[0300] Thus, the fairing can be folded lengthwise to the length of the front part 117 and moved up to the platform 107 to be completely covered by the platform 107 in the plan view (which makes this design compatible with the swim platform 107 and not affecting the dimensions of the boat 101), while exposing the tailing edges 111.

[0301] In this way, the combined simultaneous retraction of the bottom fairing 112 (by rotating it around the axis at the rear edge 116), as well as the folding the after part 121 into the cavity of the hollow front part 117 and retraction of the transom fairing (pulling it up to the swim platform 107), should expose the trailing edges 109 and 111 of the forward cambered planing surface 108 and the aft cambered stabilizing planing surface 110, ensuring the efficient operation of the boat 101 in its main high-speed planing mode.

[0302] FIG. 14 depicts a schematic diagram illustrating a perspective aft bottom view of a stepped hull planing boat featuring cambered planing surfaces, provided with bottom and transom fairings according to some embodiments, wherein the fairings are shown folded and retracted for operation in high-speed planing mode of motion.

[0303] The planing boat 101, presumably operating in high-speed planing mode and shown here in an upside-down position, has a substantially vertical transom 102, sides 103, dihedral bottom surfaces 104, chines 105, a keel line 106 and a swim platform 107.

[0304] As a stepped hull planing boat with cambered planing surfaces, the boat 101 features a hydrodynamic system comprising a bottom step provided with a dihedral and swept-back cambered planing surface 108, as the forward planing surface, with its trailing edges 109 representing the edges of the bottom step, and a dihedral aft stabilizing cambered planing surface 110 with its trailing edges 111 representing the lower edges of the transom 102, and lateral deflectors 701, wherein cambered planing surfaces 108 and 110 are arranged successively along the bottom 104 of the boat 101 and represent a single interconnected hydrodynamic planing system of the boat 101.

[0305] In this embodiment the forward planing surface 108 extends laterally beyond the width of the chines 105 by means of external projections 1301 representing profiled continuations of the planing surface 108 outside the chines 105, which provides the planing surface 108 with a higher aspect ratio (and, so, higher hydrodynamic efficiency), while the streamlined longitudinal profiles of the projections 1301 do not have a significant effect on the hydrodynamic resistance of the boat 101 in displacement mode.

[0306] The boat 101 is provided with a system of movable relative to the hull of the boat 101 retractable fairings comprising two halves of a swept-back dihedral bottom fairing 112, symmetrical relative to the central plane of the boat 101, and a transom fairing located aft of the transom 102 under the swim platform 107, and consisting of a hollow front part 117 and an after part 121 movable relative to the front part 117.

[0307] Each half of the bottom fairing 112 features a leading edge 113, a bulge 114, a convex tail section 1201, an end cover 1202 and a rear edge 116 that extends along the axis of rotation of the bottom fairing 112 and is substantially parallel to the swept-back trailing edge 109 of the forward cambered planing surface 108 and, so, the edge of the step.

[0308] It is assumed that in the operational position corresponding to the boat's movement in displacement and partially transitional modes, the front part 117 and after part 121 should be arranged successively along the length of the boat 101 forming a continuous smooth surface of the transom fairing, whereas in the embodiment shown in FIG. 14, corresponding to the high-speed planing mode of the boat 101, the transom fairing is shown folded, with the after part 121 placed inside the hollow front part 117, and retracted, that is, raised up (lowered down in this inverted view) to the platform 107.

[0309] The transom fairing represented here by the hollow front part 117 (with the after part 121 placed inside) has a leading edge 118, a rear edge 119 an upper edge 120, while the shape of the transom fairing features a bulge 122, a convex tail section 123 and protruding chines 1102 and deflectors 1103 tapering astern and representing a continuation of the chines 105 and deflectors 701 of the hull of the boat 101, so that the chines 1102 and deflectors 1103 are, actually, the aft fairings for these hull protrusions.

[0310] The shape and profiling of the bottom 112 and transom fairings are supposed to be made in accordance with the provisions of the present invention, and thus, in the lower operational position of the fairings corresponding to the low-speed displacement and partially transitional modes, it assumes that:

[0311] (1) the leading edges 113 and 118 of the bottom fairing 112 and the transom fairing are shaped to conform to the trailing edges 109 of the forward cambered planing surface 108 and 111 of the aft cambered planing surface 110, abut upon and fit flush with the trailing edges 109 and 111, respectively;

[0312] (2) in sections by vertical longitudinal planes, tangents to contours of the bottom fairing 112 at leading edges 113 and the transom fairing at leading edges 118 are inclined at positive angles (i.e., the tangents are turned counterclockwise relative to the horizon when viewed from the starboard side of the boat 101) being equal to the angles of inclination of tangents to corresponding same-plane contours of the forward cambered planing surface 108 at its trailing edges 109 and the aft cambered planing surface 110 at its trailing edges 111, respectively;

[0313] (3) in sections by vertical longitudinal planes, following the contours of the bottom fairing 112 and the transom fairing aftward, the tangents to said contours rotate clockwise, i.e., their positive angles of inclination decrease, and the tangents gradually come to the zero-angle horizontal position, and then the angles become negative, while their moduli (absolute values) increase when moving aft, providing that in total the tangents rotate by angles greater than the initial angles of their inclination at leading edges 113 and 118.

[0314] Such progression of tangents forms the bulge 114 in the forward part of the bottom fairing 112 and the bulge 122 in the forward part of the transom fairing, which bulges 114 and 122 are arranged along the leading edges 113 and 118 (and, so, trailing edges 109 and 111), and should protrude in the lower operational position of the fairings below the trailing edges 109 and 111 in projection onto the transverse plane.

[0315] The tail portions: 1201 of the bottom fairing 112 and 123 of the transom fairing, are represented in sections by vertical longitudinal planes with convex curves behind the rearmost points of the bulges 114 and 122, while, at the points of connection, the angles of inclination of tangents to these convex curves and the tangents to the contours of the bulges 114 and 122 are equal, which means that, following the contours aftward, the tangents to the contours of the sections of the fairings aft of the bulges 114 and 122 continue to gradually rotate clockwise, forming convex tail shapes of the fairings.

[0316] Following the above requirements, which correspond the provisions of this invention, the system of two fairings, i.e., the bottom fairing 112 and the transom fairing consisting of the front 117 and after 121 parts, located, respectively, behind the bottom step and the transom 102 and shaped to match the profiles of the cambered planing surfaces 108 and 110 of the boat 101, being put to the lower operational position, would ensure the formation of a continuous smooth bottom surface, providing at low Froude numbers a smooth, continuous and separation-free flow along the bottom of boat 101, which would result in low hydrodynamic resistance and the efficient operation of the boat 101 in displacement and partially transitional motion modes, manifested in a decrease in power and fuel consumption and an increase in the cruising range of the boat 101.

[0317] In order to ensure efficient operation of the boat 101 in the presumed in FIG. 14 main high-speed planing mode of motion, at high Froude numbers the flow must come off the trailing edges 109 and 111 of planing surfaces 108 and 110, for which the trailing edges 109 and 111 (their back sides) must be exposed to the atmospheric air by means of the formation of substantially vertical steps along the contours of these edges.

[0318] For this purpose, the retractable bottom 112 and transom fairings are raised to the upper (shown as lower in this upside-down view) inactive position, intended to expose the trailing edges 109 in the case of the fairing 112 and, in the case of the transom fairing, to expose the trailing edges 111 in order to form the transom step 201 extending from the trailing edges 111 up to the raised leading edges 118 of the front part 117.

[0319] To carry out such retraction, each half of the bottom fairing 112 was rotated around the axis extending along the rear edge 116, so that, having been turned upward (by hydraulic or electrohydraulic actuator, e.g.), the halves of the fairing 112, including their bulges 114, came to the position above (below in this inverted view) the trailing edges 109 in projection onto the transverse plane, which position raised the leading edge 113 of each half and formed a substantially vertical step, and this way exposed the trailing edge 109 to ensure efficient operation of the boat 101 in its high-speed planing mode.

[0320] In order to expose the trailing edge 111, which is necessary for effective planing of the surface 110, the transom fairing is made both foldable and retractable.

[0321] In the lower operational position, the transom fairing supposed to be composed by successively arranged the front part 117 and the after part 121, which adjoining parts form a configuration tapering aftward from the transom 102.

[0322] Such a shape of the transom fairing (which is optimal for small Froude numbers) ensures a smooth and separation-free flow aft of the transom 102 and results in low hydrodynamic resistance (meaning higher hydrodynamic efficiency), which leads to a decrease in the power required to propel the boat 101, a decrease in fuel consumption and a corresponding increase in cruising range when sailing in the displacement mode. Due to the assumed tapering aft configuration of the fairing, the after part 121 does not extend beyond the contour of the edge 119 in projection onto the transverse plane, which made it possible to move the after part 121 forward and fold it (by means of electric linear actuator, e.g.) inside the cavity of the hollow front part 117.

[0323] Then, in order to expose the trailing edge 111, the transom fairing (i.e., the front part 117 with the after part 121 folded inside) is raised up to the position where its upper edge 120 touches the bottom of the platform 107. In the embodiment of FIG. 14, wherein the boat 101 is equipped with a swim platform 107 completely covering the front part 117 in the plan view, the transom fairing (compactly folded to the length of the front part 117) is completely placed under the swim platform 107, which makes this design compatible with the platform 107 and does not increase the dimensions of the boat 101.

[0324] To carry out said lifting, in the embodiment shown in the FIG. 14, the transom fairing (specifically its front part 117) is supposed to be suspended on the transom 102 by means of double-lever parallelogram mechanisms driven by electrohydraulic actuators. As a result, the leading edge 118 (and the bulge 122) rose above the trailing edge 111 and exposed a substantially vertical surface of the lower part of the transom 102 and thus formed a vertical step 201 opening the trailing edge 111, providing access of atmospheric air to the edge 111 and effective planing of the aft cambered surface 110. Consequently, the combined simultaneous retraction of the bottom fairing 112 (by rotating it around the axis at the rear edge 116), as well as the folding the after part 121 into the cavity of the hollow front part 117 and retraction of the transom fairing (pulling it up to the swim platform 107), exposed the trailing edges 109 and 111 of the forward cambered planing surface 108 and the aft cambered stabilizing planing surface 110, ensuring the efficient operation of the boat 101 in its main high-speed planing mode.

Claims

1. A planing boat with its vertical longitudinal center plane and a hull featuring a stepped bottom with at least one step provided with a cambered planing surface as a bottom surface of this step, so that edges of said step represent trailing edges of said cambered planing surface, which boat is provided with at least one movable relative the hull fairing located aft of said trailing edges and having a leading edge, while said leading edge of the fairing in its lower operational position, corresponding to low-speed displacement and transitional modes of the boat, is predominantly shaped to conform to, abuts upon and fits flush with said trailing edges at least along some length of said trailing edges,wherein, within said length of the trailing edges and along the line of abutment of said leading and trailing edges, in sections by vertical longitudinal planes, at the points of abutment of the outer contours of the cambered planing surface of boat bottom and the surface of fairing, the angles of inclination of tangents to the outer contours of the surface of fairing are positive and substantially equal to the angles of inclination of tangents to the outer contours of the cambered planing surface of boat bottom, that is, at said points of abutment, the tangents are turned counterclockwise relative to the horizon at an angle less than 90 degrees when viewed from the starboard side of the boat,while, when moving aft along at least the forward part of said contours of the fairing outer surface, the angles of inclination of the tangents to the contours gradually decrease and, at some distance aft from the leading edge, the tangents come to the zero-angle horizontal position, and then the angles of inclination of the tangents become negative, while their absolute values increase when moving along the contours of the fairing further aft,so that, when moving aft along at least the forward part of the contours of the fairing outer surface, the tangents to the contours of the fairing outer surface rotate clockwise, when viewed from the starboard side of the boat, at angles greater than the initial angles of inclination of the tangents to the horizon at the point corresponding to the abutment of the outer contours of the cambered planing surface and the fairing, forming convexities of the outer contours of the fairing and a bulge of the fairing arranged substantially along the trailing edges and protruding downwards below the trailing edges in projection onto the transverse plane,whereas, when the boat is in its main operational high-speed planing mode, the fairing is in its upper inactive position, in which the leading edge of the fairing, said bulge and the fairing as a whole, are located higher than the trailing edges of said cambered planing surface of boat bottom in projection onto the transverse plane.

2. A planing boat according to claim 1, wherein parts of the contours of the outer surface of the fairing aft of said bulges are straight lines.

3. A planing boat according to claim 2, wherein the angles of inclination to the horizon of the straight lines aft of the convexities are substantially equal to the angles of inclination of the tangents to said convexities at their rearmost points.

4. A planing boat according to claim 1, wherein the tangents to the outer contours of the fairing, when moving aft along the contours and aft of said convexities, gradually turn counterclockwise when viewed from the starboard side of the boat, forming a concave contour of the outer surface of fairing in its aft part.

5. A planing boat according to claim 1, wherein at least one fairing is movable substantially vertically relative to the boat hull.

6. A planing boat according to claim 1, wherein at least one fairing is rotatable relative to the boat hull about an axis at the aft part of the fairing.

7. A planing boat according to claim 1, wherein at least one fairing is suspended on the hull by means of at least one double-lever parallelogram mechanism comprising levers and hinges at the ends of these levers, so that the hinges of one end of the levers are attached to the hull, and the hinges of the other end of the levers are attached to the fairing.

8. A planing boat according to claim 1, having at least two cambered planing surfaces, successively arranged lengthwise, and at least one fairing located aft of each of said cambered planing surfaces breadthwise.

9. A planing boat according to claim 8, having a bottom step with a swept back substantially dihedral forward cambered planing surface, symmetrical relative to its vertical longitudinal center plane, wherein each symmetrical relative to the center plane half of said forward planing surface is provided with its own fairing, rotatable relative to the hull around an axis in the aft part of the fairing, which axis in the plan view is arranged at an angle less than 90 degrees to the aft part of boat keel line, and inclined at some angle of deadrise in projection onto the transverse plane.

10. A planing boat according to claim 9, wherein said axis is substantially parallel to the corresponding trailing edge of said forward cambered planing surface.

11. A planing boat according to claim 8, wherein the rear transom fairing comprises at least two parts, successively arranged lengthwise when in the low operational position, while the rear part of the fairing is made movable relative to the adjacent front part.

12. A planing boat according to claim 11, wherein the rear part of the transom fairing can be moved forward into the cavity of the adjacent hollow front part of the fairing.

13. A planing boat according to claim 11, wherein the rear part of the transom fairing is made rotatable relative to the adjacent front part about a substantially normal to the center plane axis and can be rotated forward for folding over the front part of the fairing.

14. A planing boat according to claim 1, wherein the shell of said fairing is reinforced with frames and stringers.

15. A planing boat according to claim 1, wherein the fairing is hollow and provided with drainage holes or slots.

16. A planing boat according to claim 1, wherein the transom fairing is provided with at least one recess shaped to accommodate outboard motor, stern drive or surface drive.

17. A planing boat according to claim 1, wherein said fairing, movable relative to the hull as a whole, as well as each movable part of the fairing, are driven by at least one hydraulic or electrohydraulic actuator, a worm drive or electric linear actuator.

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