Sail propulsion element, sail-propelled vehicle

Abstract

The present invention relates to a sail propulsion element comprising a mast (3) and an inflatable sail (1) consisting essentially of two adjacent surfaces (5) substantially fluid-tight, said two adjacent surfaces (5) being joined together around their periphery to form at least one closed cavity therebetween, said sail having an upper part (6), a lower part (7), a leading edge (8) and a trailing edge (9), said sail including various curvatures forming a bulge over its length, at least one air duct arranged between the inside and the outside of the sail cavity, and at least one means for injecting air into the cavity, said sail having a profile which, when inflated, remains permanently symmetrical regardless of the movement of the propulsion element or the direction or strength of the wind, a headboard (10) arranged on the upper part (6) of the sail, and a sail receptacle (11) arranged on the lower part of the sail between the leading edge (8) and the trailing edge (9). The element according to the invention is characterized in that it comprises a guide line (12) arranged in a closed cavity of the sail for the operations of hoisting and dropping the sail, the guide line extending from the leading edge (8) to the trailing edge (9) of the sail through the headboard (10) and the sail receptacle (11).

Description

[Technical field]

[0001] The present invention relates to inflatable sails and is in the field of sail propulsion or hybrid sail propulsion. [Background technology]

[0002] A reminder of some definitions used below is set out below. Reefing: Consists of reducing the surface area of ​​a sail by furling a portion of it from the bottom so as to adapt it to the wind strength. Reefing can be done manually or automatically. Reefing band: A partially reinforced horizontal zone to which a reefing turning block can be attached, for example by means of grommets or pulleys. There are as many reefing bands as there are sail reefing possibilities. Lazy jacks: Devices that guide a sail during the reefing and dropping action of the sail. Boom: A horizontal spar near the base of the mast that holds and allows a particular sail to point. The boom can also receive a sail when it is dropped. Luffing: A luffing sail is one that is underhauled and therefore partially deflated. A well-trimmed sail should be at its luffing limit. If the sail is properly filled, luffing will not occur and you can sail close to the wind. Leading edge: The front part of an aerodynamic profile (wing, propeller, etc.) where the fluid splits into two streams. Trailing edge: The distinctive part of any profile (wing, keel, rudder blade, etc.) that is exposed on either side to the flow of fluid (air, water, etc.) - the part facing away from the sense of direction, i.e. the part aft when viewed in the direction of the flow. Headboard: The upper edge of a sail that conforms to the upper contour of an inflatable sail. Dropping: Consists of lowering a sail. Hoisting: Consists of raising a sail. Rigging: The collection of fixed and movable parts on a sailboat-type boat that enables it to be propelled and steered using the power of the wind. Sail receptacle: In addition to receiving a dropped sail, it can incorporate other functions such as reacting to tension supplied by the sail or housing other actuators, energy storage sensors, and control modules used in the operation of the sail. Hydrodynamic drag: The frictional force between the boat and the water. The more drag there is, the more the boat slows down. Aerodynamic drag: The component of force experienced by an object moving through a fluid that acts in a direction opposite to the direction of movement. In accordance with the present invention, a sail generates aerodynamic drag. Aerodynamic lift: The component of force acting perpendicular to the direction of motion of an object moving through a fluid. In accordance with the present invention, a sail generates aerodynamic lift. Relative or apparent wind: The vector sum of the wind caused by the boat's specific speed and the actual wind speed. Aerodynamic resultant: The vector sum of the aerodynamic lift and aerodynamic drag forces.

[0003] (prior art) A sail propulsion element with an inflatable sail having a symmetrical profile is known from document WO2017 / 221117A1. The propulsion element comprises an inflatable sail consisting essentially of two substantially fluid-tight adjacent faces joined together along their periphery to form at least one closed cavity. The element further comprises a conduit arranged between the inside and the outside of the cavity and a means for injecting air into the cavity. When inflated, the sail has a profile that remains permanently symmetrical, regardless of the movement of the element or the wind direction or strength. The sail of the document is constantly inflated while being used for sailing.

[0004] Unfortunately, such soft sails have the drawback of not providing suitable inflation levels for the various stages of their use, especially the hoisting and dropping stages. Specifically, unlike hard sails, soft sails do not have a clearly defined position during these stages of handling (hoisting and dropping). During these stages, it is important to keep the sail close to the axis of symmetry of the sail profile, to avoid the sail dropping into the water or getting caught in nearby elements, or collapsing in a poorly defined area and becoming unable to be packed compactly. Furthermore, it is important to maintain a slight pressure on the sail during the dropping or reefing stages to prevent the sail from becoming luffing, which could reduce the life of the sail.

[0005] A device for hoisting and dropping a conventional sail of a sailboat using a guide solution external to the sail is also known from document US2006174810A1. This process can be easily performed with one hand and allows continuous control in absolutely any intermediate position during lowering or hoisting, allowing the sail to be quickly adapted to different wind conditions.

[0006] Unfortunately, such sail management devices are located on the outside of the sail, resulting in increased drag, and furthermore, such devices are fixed to the boom and mast and cannot be attached to a telescopic mast.

[0007] Document GB2151199A describes an inflatable boat sail which includes in its internal cavity a system of lace-type flexible mechanical links connecting the two walls forming the sail. This system is distributed over the entire height of the sail and is fixed to the lower part of the mast. The purpose is to allow optimal operation of the sail from an aerodynamic point of view in these various uses.

[0008] Unfortunately, such systems remain complex and unsuitable for managing the repeated hoisting and dropping of an inflated sail.

[0009] Finally, those skilled in the art are aware of the use of line rope rigging devices external to conventional sails that are secured to the boom and for maneuverability of the boom during hoist and drop operations.

[0010] However, such devices increase the drag on the sailboat, thus compromising its speed, and cannot be mounted on telescoping masts. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2017 / 221117 [Patent Document 2] US Patent Publication No. 2006 / 174810 [Patent Document 3] GB 2151199 Summary of the Invention

[0012] Thus, a need remains for an inflatable sail that does not luff, stays correctly on its axis of symmetry along the mast during drop, and can be repeatedly deployed manually or automatically without risk of becoming damaged.

[0013] One subject of the invention is a sail propulsion element comprising a mast, an inflatable sail consisting essentially of two adjacent substantially fluid-tight surfaces joined along their periphery to form at least one closed cavity between them, said sail including an upper part, a lower part, a leading edge and a trailing edge, the sail including a variable camber forming a bulge along its entire length, at least one air conduit arranged between the inside and the outside of the cavity of the sail, at least one means for injecting air into the cavity, such that the inflated sail has a profile that remains permanently symmetrical regardless of the movement of the propulsion element or the direction or strength of the wind, a headboard arranged on the upper part of the sail, and a sail receptacle arranged between the leading and trailing edges of the lower part of the sail.

[0014] The propulsion element according to the present invention comprises at least one guide line arranged in a closed cavity of the sail for the operation of hoisting and dropping the sail, the guide line extending from the leading edge to the trailing edge of the sail through the headboard and the sail receptacle.

[0015] More specifically, the guide line is a device generated through the rigging of the line ropes to enable the sail to be geometrically correctly positioned during operation and during the hoisting or dropping phase. An inflatable sail (or wing) comprises a number of cambers (or sections) separated from each other by ribs, the ribs being located between two adjacent cambers. The ribs of the sail are considered to be, for example, in the middle of the sail's height and are constrained in position by allowing the mast to pass through an orifice formed in the rib, but there is nothing to prevent the sail from rotating relative to the mast under the effect of the pressure on the sail, apart from the stiffness of the sail (which is low). Such a rotation would have the effect of causing a twisting of the sail and thus reducing its performance. To avoid this twisting, each rib has a guide line passing through it, located at a sufficient distance from the mast. During hoisting or dropping, the rib slides along the mast and along this guide line. This also applies to all the ribs that make up the sail's cambers, the guide line passing through all of these ribs.

[0016] In other words, the invention proposes at least one guideline to be placed in the closed cavity of the sail, intended to assist in the hoisting and dropping operations of the sail and to ensure that the inflated sail (or wing) maintains the correct geometric shape under all operating conditions of the sail.

[0017] This guideline is not intended for hoisting a sail, which is furthermore under slight tension during the hoisting phase and for this very reason inhibits the raising of the sail. In the context of the present invention, the sail is hoisted by a telescoping mast supporting a headboard, which pulls the sail upwards as it inflates. In versions of the present invention where the mast is not telescoping, the sail is hoisted by movement of the headboard along the mast.

[0018] The propulsion element according to the invention offers various advantages: The guideline present in the cavity of the sail, unlike conventional rigging, avoids the unnecessary generation of additional drag. The guideline according to the invention makes it possible to guide the lowering and raising of the sail correctly (meaning without twisting) towards its storage place located in the sail receptacle. The guideline according to the invention allows the sail tension to be relatively low (approximately 100m 2 This allows for a maximum load of approximately 50N for a sail.

[0019] Finally, the element according to the invention allows the sail to be reefed without the need to stop the boat: only the sail needs to face the wind, unlike conventional devices which require the entire boat to face the wind.

[0020] Preferably the guide line is one piece and is fixedly attached to a sail receptacle on the trailing edge and movable by rollers on the leading edge, or alternatively it can be movable by rollers at a sail receptacle on the trailing edge and fixedly attached to the leading edge, and is positioned along the headboard so that the guide line can move on at least one pulley between the trailing edge and the leading edge.

[0021] Preferably, the guideline has two parts, a first part on the trailing edge side which is either fixed or movable on a pulley on the headboard and movable by a roller in a receptacle, and a second part on the leading edge side which is either fixed or movable on a pulley on the headboard and movable by a roller in a receptacle.

[0022] Preferably, the pulley provides limited friction compared to the grommet.

[0023] Preferably, at least two guide lines allow for more accurate guidance. The presence of multiple guide lines allows for selective weight distribution, which can improve the accuracy of guidance. Reefing points can also be useful for guidance.

[0024] Preferably, the guideline is 10 to 1000 m. 2 A sail of 2 to 150 m, preferably 100 m 2 The sail is about 50m long.

[0025] Preferably, the guidelines are from 10 to 1000 m. 2 sails of 5 to 500N, preferably 100m 2 The sail has a tension of 50 to 250N.

[0026] Preferably the sail includes at least one reefing panel, more particularly 0 to 10 reefing panels. A cargo boat may have zero reefing points, but a sailboat mainsail may have more than three reefing points.

[0027] Preferably, the leafing panel includes a reinforcing rib.

[0028] Preferably the mast is fixed or telescoping.

[0029] Preferably, the guidelines are made from extra-strong polyethylene fibers.

[0030] Another subject of the invention is a vehicle with sail or hybrid propulsion comprising at least one sail propulsion element as described herein above, a hull and a mast fixed to said hull but still rotatable, characterized in that the mast is arranged in the cavity of the inflatable sail described above.

[0031] A hybrid propulsion vehicle according to the present invention means sail propulsion combined with another propulsion source, such as propulsion using a propeller driven by an electric motor or an internal combustion engine, and has as energy storage sources batteries, hydrogen (with fuel cells), natural gas, ammonia or fuel oil.

[0032] Mobile objects are meant to include land yachts, ice yachts, boats and automobiles.

[0033] Preferably, the sails are oriented, manually or automatically, according to the wind direction and according to the direction of travel of the mobile body, so as to optimize the propulsion along the axis of the boat, or to achieve the desired propulsion while limiting the load, pressure and heeling to acceptable values.

[0034] The invention is illustrated by the following figures, which are schematic and are not necessarily drawn to scale. [Brief description of the drawings]

[0035] [Figure 1] 1 shows the projection of various physical forces applied to a watercraft, for example of the motor sailboat type, and in particular the resulting aerodynamic forces. [Diagram 2] FIG. 1 is a schematic cross-sectional view of a sail propulsion element according to the invention arranged on a boat hull. [Diagram 3] FIG. 11 is a schematic cross-sectional view of a sail propulsion element according to another variant of the invention, arranged on a boat hull. [Figure 4A] 2 shows a schematic view from above of the position of a propulsion element according to the invention according to different relative wind angles; [Figure 4B] 2 shows a schematic view from above of the position of a propulsion element according to the invention according to different relative wind angles; [Figure 4C] 2 shows a schematic view from above of the position of a propulsion element according to the invention according to different relative wind angles; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Before describing in more detail the sail propulsion elements which form the subject of the present invention and with the aid of the figures mentioned above, a reminder of some hydrodynamic and aerodynamic definitions is given below.

[0037] A sail-propelled vehicle (hereafter referred to as a sailboat or vessel) is in contact with air and water. From a physical point of view, the main factors are the hydrodynamic and aerodynamic forces acting on the hull, sails and appendages (centerboard, keel, rudder, propeller).

[0038] As shown in Figure 1, aerodynamic forces (or sail thrust) are the result of air being deflected by at least one sail. Aerodynamic forces are related to the position and surface area of ​​the sail, and the position and strength of the relative wind. Drag is in the direction of the relative wind, and lift is perpendicular to the relative wind, which is not always perpendicular to the sail. For example, at 0°, a symmetrical profile would not generate lift, since the air travels exactly the same distance across the outer and inner arcs. At this point, it would only generate drag.

[0039] The aerodynamic forces generated by a sail can also be resolved, in the frame of reference of the boat rather than the sail, into a sail thrust force (along the axis of the boat's travel) and a drift force (perpendicular to the axis of the boat) which can cause the boat to heel (heel is the lateral tilt of the board as caused by an external phenomenon such as wind).

[0040] Hydrodynamic forces are the result of the friction of water against the hull and centerboard or keel and various underwater appendages. Their direction depends on the opposing aerodynamic forces, the propulsive forces in hybrid mode, sea conditions and currents. The longitudinal component is called hydrodynamic drag and the transverse component is called side force, anti-heeling force or hydrodynamic lift. The direction and strength of hydrodynamic forces do not depend only on aerodynamic forces. For surface vessels (boats) operating in hybrid mode (wind and another energy source), the hydrodynamic forces are highly dependent on the vessel speed generated by the engine or motor propulsion, e.g. sea conditions and currents.

[0041] When the force of the sail is greater than the hydrodynamic force, the boat will accelerate. When the force of the sail is less than the hydrodynamic force, the boat will slow down. Additionally, if the aerodynamic force is greater but directed towards the rear of the boat, the boat will slow down. If the hydrodynamic force is in the direction of the boat's travel (for example as a result of a strong current), the boat (a sailboat) will accelerate.

[0042] By optimizing the trim of the sail, the boat (sailboat) will achieve its maximum performance in terms of sail thrust in the direction of travel. Specifically, by optimizing the angle of the sail with respect to the relative wind and the direction of travel of the boat, and by trimming the surface area of ​​the sail, the boat can achieve the maximum level of sail thrust along the axis of the boat. In addition to this, there can be additional trimming parameters, including varying the internal pressure of the sail. This makes it possible to increase the speed of the boat, while at the same time reducing the consumption of other energy sources in favor of sail power, while maintaining the same speed.

[0043] FIG. 1 again illustrates each of the above defined parameters with a unique specific reference number, all as listed below. a: Lift b: Drag force c: aerodynamic resultant force d: Aerodynamic thrust (along the axis of the ship) e: aerodynamic drift force f: relative wind g: Relative angle between wing and boat axis (e.g. 15°) h: angle between relative wind and boat axis (e.g. 30°) i: Propeller thrust j: Haru k: Sale l: Mast m: center of aerodynamic thrust n: Propeller o: Sensor in fixed part (hull reference frame) p: Sensor of moving part (sail reference frame) The information given in FIG. 1 allows the transition from sensors in the hull reference frame to sensors in the sail reference frame and vice versa.

[0044] Figure 2 shows a sail propulsion element according to the invention mounted on a boat of sailboat type in operating position. The element comprises a sail, with the general reference 1, mounted on the hull 2 ​​of the boat. The element comprises a mast 3, the foot 4 of which is fixed to the hull 2 ​​while allowing a rotational movement. The mast 3 is free-standing. The mast 3 is connected to the hull 2 ​​by means of a support (not shown) intended to absorb the loads of physical forces and leave a degree of rotational freedom. The loads are measured at the support. The sail 1 comprises two adjacent faces 5 (only one is visible in the figure) connected to each other to form a closed cavity. The material used for the two adjacent faces 5 must have limited permeability to reduce air consumption and to allow the various loads involved to react and transmit. In some cases it may be necessary to apply various treatments to the material, for example to ensure a certain UV resistance and / or antistatic behavior.

[0045] The sail 1 has multiple cambers (not shown) evenly distributed over its height (the camber is larger in the lower part of the sail and smaller in the upper part). The height of the cambers is often linked to the length of the chord of the profile. Preferably, the cambers are separated by ribs, allowing air to pass from one camber to another, and each has an orifice through which the mast can pass.

[0046] The camber gives it a concertina-like appearance. The sail 1 includes an upper portion 6, a lower portion 7, a leading edge 8 and a trailing edge 9. At least one air inlet 18 is located, for example, in the lower portion 7 of the sail 1. Another air inlet 30 may also be located in the surface of the leading edge 8. At least one active means 7a for injecting air into the sail cavity is located in the continuation of the air conduit so that air can be injected into the sail cavity. The sail further comprises a headboard 10 located in the upper portion 6 and a sail receptacle 11 located in the lower portion 7 between the leading edge 8 and the trailing edge 9. The receptacle 11 is for receiving all or part of the sail when it is dropped. The receptacle 11 may comprise various actuators and sensors to facilitate manual or automatic operation of hoisting or dropping the sail 1.

[0047] The sail propulsion element according to the invention comprises a guide line 12 arranged in a cavity of the sail 1. This guide line is intended to guide the sail 1 during hoisting and dropping operations and reefing operations. This line 12 comprises a line rope rigging that extends substantially around the circumference of the sail 1. The guide line 12 is fixed removably or non-removably, but is not movable at an end 13 close to the intersection between the trailing edge 9 and the sail receptacle 11. The line then extends towards the upper part 6 of the sail 1 and runs along the headboard 10 between the trailing edge 9 and the leading edge 8. This guide line 12 can move along the headboard 10 with the aid of at least two pulleys or other rotation block systems (not shown), one located on each side of the mast 3. This guide line 12 is adjacent to the leading edge 8 and towards the sail receptacle 11, and is fixed on the sail receptacle 11 by means of rollers 19 substantially at the leading edge 8. The guide line 12 can be pulled up towards the release cleat when manually actuated, whereas in the automated version the guide line 12 is wound on automatic rollers.

[0048] More specifically, the guideline rigging passes through all of the ribs that separate the various cambers that form the inflatable sail. To prevent the various ribs from rotating around the mast, each rib has an oval slot through which the guideline rigging passes on its leading edge and another oval slot through which the guideline rigging passes on its trailing edge. The oval slots allow the line rope rigging to pass through the ribs in all positions that the ribs take along the mast when the sail is being hoisted and dropped. In this way, even though the ribs as well as the sail are made of flexible material, the ribs are prevented from rotating relative to the mast, which allows the sail to maintain its profile during operation, particularly during the hoisting and dropping of the sail.

[0049] Unlike prior art systems that are permanently fixed to the outside of the sail using lazy jacks, the guideline rigging of the present invention is on the inside of the sail and its length is adjusted to ensure a slight tension that keeps the inflatable sail (or wing) in place. This rigging moves with the headboard, which is located at the top of the sail, ensuring a slight tension on the guideline rigging at all times.

[0050] Guideline 12 is approximately 100m 2 It has a length of about 50m for a sail with a total surface area of ​​about 100m and has a tension of about 50 to 250N depending on the application to which it is put during the various drop and hoisting operations.

[0051] The mast 3 can be telescopic or fixed. If the mast 3 is telescopic, the headboard 10 is fixed to the last element of the telescopic mast 3 and can maintain rotational freedom by allowing it to rotate relative to the mast or by allowing the last element of the telescopic mast itself to rotate. If the mast 3 is telescopic, it is made up of various elements that slide sequentially over each other to extend and retract. It is also possible to extend all elements simultaneously if no intermediate sail positions are required.

[0052] When the mast 3 is fixed, only the headboard 10 is movable along the mast 3. The sail 1 is fixed to the headboard 10 and rises or falls together therewith.

[0053] It is also possible to combine a telescoping mast 3 and a headboard 10 which slides along the mast 3 .

[0054] The headboard 10 is sufficiently rigid to be able to impart the physical forces present between the various line ropes and the mast 3, and to withstand the weight of the sail when the sail is uninflated. According to various embodiments of the invention, the headboard 10 may be free to rotate about the mast 3 as desired, may be prevented from rotating about the mast 3, may be prevented from rotating about the mast 3 up to a maximum limiting torque value to limit the load to an acceptable value, or alternatively may be feedback controlled to control the twist of the sail.

[0055] The mast 3 is fixed to the hull 2 ​​using a mast support 14, the purpose of which is to react the various physical forces between the sail and the boat whilst leaving the mast 3 some freedom to rotate so that it can be positioned at the correct angle to the relative wind.

[0056] At the foot of the mast 3, i.e. at the hull 2, there is a system 15 for adjusting the incidence angle, which makes it possible to command the sail 1 to rotate by rotating the mast 3 and all the steering parts fixed to said mast 3. This system 15 may in particular consist of a brake motor. This system 15 makes it possible for the sail 1 to rotate about the axis of rotation of the mast 3 and thus to command the desired incidence angle of the sail 1. This incidence setting system may also be fixedly mounted to the mast 3, for example on a "nest" (or sail receptacle), the brake motor driving, via a pinion, a ring gear fixed to the hull.

[0057] It will be recalled that by measuring the angle of incidence, the angular positioning of sail 1 relative to the axis of the boat can be determined. Such a device allows sail 1, hull 2 ​​and the relative wind to be placed in one and the same reference frame, regardless of where the wind is measured on sail 1 or on hull 2. Such a system simplifies sailing in automatic mode.

[0058] The propulsion element according to the invention, arranged on the hull of the boat, can also be combined with a torque limiter, arranged at the foot of the mast 3 and known for limiting the maximum torque that the sail 1 can transmit to the hull 2.

[0059] The propulsion element according to the invention, arranged on the hull of the boat, may further comprise an electronic control system 16 arranged in the sail receptacle 11, also called the "nest". A rotary electric joint 17 may also be added in the hull, at the lower base of the mast 3. This joint 17 allows the transmission of power and electrical commands between the hull 2 ​​and the lower part 7 of the sail 1. The joint 17 may also be replaced by a conventional suitable cable-bearing chain. If the power used to operate the sail element according to the invention is, for example, hydraulic or pneumatic, the same solution may be adopted with a rotary hydraulic or pneumatic joint.

[0060] Among the various measurement sensors there may be sensors measuring the loads transmitted from the sail 1 to the hull 2, sensors measuring the loads in the transverse axis of the hull 2, sensors measuring the loads in the longitudinal axis of the hull 2, sensors measuring the pressure in the internal cavity of the sail 1, and sensors measuring the relative wind speed and angle. This last measurement may be made equally on the sail 1 or on the hull 2. If the sensor is placed on the part fixed to the mast 3, it measures the loads along the longitudinal and transverse axes of the sail 1.

[0061] FIG. 3 differs from FIG. 2 by the addition of a reefing pendant system consisting of a reefing panel (or grid) 20, reefing lines 21, and a reefing winch 22 (which can be substituted with cleats and muscle power in manual mode).

[0062] The propulsion element according to the invention can include several reefing panels 20, for example up to three reefing panels 20. The number of these panels 20 depends on the boat, the application and the user. A roofing panel 20 is arranged in each reefing band.

[0063] The reefing lines are connected to the reefing panels 20 and allow the sails 1 to be stowed back into the receptacles 11. The grid is sufficiently stiff that point loads at pulleys fixed to the grid can be transmitted to the whole of the reefing panels 20.

[0064] Associated with each reefing point intended to reduce the volume of the sail to a certain level is a reefing panel 20 and a reefing line. The reefing lines can be manufactured as a single line with the turning block or as separate lines.

[0065] In conventional sails of the prior art, each reefing point has a grommet through which a reefing pendant can pass to effect reefing, and an associated pulley, or sail tie (a small length of cord that can be used to attach a furled sail by passing it under the boom from both sides).

[0066] In an inflated sail according to the invention, the grommets (or other leadthroughs) are located on the horizontal portion of the leafing panel 20, rather than on the vertical portion of the sail as in conventional sails, and so must not be fluid tight.

[0067] As a result, the reefing panel 20 (or grid) of the propulsion element of the invention is fixed to the outer wall of the sail 1. In addition to reefing, this panel 20 allows the guide lines 12 to be brought closer to the trailing edge 9 and leading edge 8, especially in the case of sails that are not substantially triangular. Furthermore, the guide lines 12 in combination with the panel 20 simultaneously apply a downward thrust to the headboards 6 on both sides of the mast 3, thereby partially equalizing the load acting on the headboards 6.

[0068] In addition to reefing, the reefing panel 20 allows the guide lines 12 to be moved closer from the leading edge 8 to the trailing edge 9, particularly in sails that are not substantially triangular.

[0069] During sail hoist operations the following steps are performed: Aligning the sail with the relative wind axis Applying initial tension to the guide lines and reefing lines The sail is inflated to a low pressure, and this pressure is feedback controlled. The sail is raised at a set speed and if the internal pressure cannot be maintained the speed limiter is activated. When the sail rises to a certain height, the pressure inside the sail increases slightly. When the reefing point is reached, the leaves are released sequentially if the surface area is to be used. The sail is stopped from rising when the sail surface area is reached, which corresponds to the sail being fully deployed or the sail being at a height corresponding to the amount of reefing in place. The sail cavity is inflated to its nominal pressure (which varies depending on wind strength, sea state and desired running speed) The sail does not need to be permanently inflated: in particular, it is possible to set a range of acceptable pressures, so that the inflation means can be used only when necessary.

[0070] During a sail drop operation, the following steps are performed: Point the sail into the relative wind (facing the wind) The internal pressure of the cavity is reduced Adjusting the tension of the guide lines and reefing lines If internal pressure cannot be maintained, use the speed limiter to lower the sail. Each time a leaf is reached, the relative leafing pendant is blocked. 2m from the final retraction of the mast, the internal pressure is set to zero, creating a slight vacuum inside the sail to compact it.

[0071] The operation of these various steps is preferably carried out in a sailing system, especially when the sail surface area is more than 500 m 2 Manual operation may be automated if sufficient personnel are available to achieve a speed equal to or exceeding 40 m. 2 This can be easily achieved with a surface area of ​​this order.

[0072] 4A, 4B and 4C differ from one another by having different sail incidence angles.

[0073] In Figure 4A the relative wind is along the axis of the sail, in Figure 4B the sail axis is at an angle to the relative wind direction substantially equal to 15°, and in Figure 4C the sail axis is at an angle to the relative wind direction that is symmetrical to and equal to the angle depicted in Figure 4B.

[0074] 4A, 4B and 4C the sail 1 has a substantially symmetrical profile. The mast 3 is represented by a circle. The relative wind is represented by an arrow 23.

[0075] Figure 4A depicts the sail 1 in a stable position facing the wind 23. The various loads are balanced and due to the symmetrical profile of the wing, the aerodynamic lift is zero since they are identical on both sides of the wing. Since the aerodynamic lift is zero, there is only a drag force 24 that keeps the sail 1 on an axis parallel to the axis of the relative wind.

[0076] Figure 4B depicts a sail 1 with its axis at an angle of approximately 15° to the relative wind direction. The axis of rotation of the mast 3 is offset towards the front of the profile with respect to the aerodynamic thrust centre 25 along the axis of symmetry of the profile. Figure 4B shows that the torque generated by the aerodynamic forces at a certain distance from the centre of rotation of the mast 3 tends to return the sail to a position facing the wind, allowing the sail to remain stable thanks to its symmetrical profile.

[0077] Due to the offset between the attachment point of the mast 3 and the centre of propulsion 25, the propulsion element of the invention is able to hold the sail 1 in position in situations of large as well as small angular deviations from the wind direction. Such an offset between the rotation point and the centre 25 of the mast 3 means that the sail 1 can be made to return towards its neutral position, i.e. facing the wind, when it deviates from said position. Such an offset makes it possible to improve sailing safety, since the sail automatically returns to the correct and optimal position with respect to the relative wind direction, thus minimizing the load and keeping the sail facing the wind. However, this distance must be minimized so as not to excessively increase the force required to turn the sail.

[0078] Figure 4C is a symmetrical view of Figure 4B with respect to the axis of the relative wind. The same applies as in Figure 4B. EXAMPLES

[0079] The following examples are presented for illustrative purposes only and are not limiting. The following table collate various possible implementations. TIFF2024521785000002.tif179150The outer layer of the sail, also called the body, is made of a woven fabric, including the outer layer in contact with the outside air and the inner layer. The fabric is a polyurethane-coated polyester fabric. The basis weight of the fabric is approximately 100 m 2180g / m for sail area 2 It is.

[0080] The upper side of the sail may be secured with hook and loop fasteners of the Velcro type. The joints between the outer part of the sail and the ribs (internal joints) and between the components of the outer part may be achieved by fusion or adhesive joints or other joining means (e.g. zip fasteners which may ensure load transfer whilst ensuring a sufficiently low level of permeability to be compatible with existing inflation systems). [Explanation of symbols]

[0081] 1 Sale 3 Mast 5 Adjacent Surfaces 6 Upper part 7 Lower part 8 Leading Edge 9 Trailing Edge 10 Headboard 11 Sail Receptacle

Claims

1. A sail propulsion element, comprising: a. a mast (3); b. an inflatable sail (1) essentially consisting of two adjacent substantially fluid-sealed surfaces (5) joined along their periphery to form at least one closed cavity between said two adjacent surfaces, said sail including an upper portion (6), a lower portion (7), a leading edge (8) and a trailing edge (9), said sail including various cambers forming a bulge along its entire length; c. at least one air duct disposed between the inside and the outside of said cavity of said sail; d. at least one means for injecting air into said cavity, said inflated sail having a profile that remains permanently symmetrical regardless of the movement of said propulsion element or the direction and strength of the wind; e. a headboard (10) disposed on the upper portion (6) of said sail (1); f. a sail receptacle (11) disposed between said leading edge (8) and said trailing edge (9) of the lower portion (7) of said sail; characterized in that it further comprises: at least one guideline (12) disposed in the closed cavity of said sail; for the operation of hoisting and dropping said sail (1), said guideline (12) extending from the leading edge (8) to the trailing edge (9) of said sail through said headboard (10) and said sail receptacle (11). A sail propulsion element, characterized in that.

2. Said guideline (12) is made of one piece and is fixedly attached to said sail receptacle (11) on said trailing edge (9), and can move on said leading edge (8) by means of a roller, or can move within said sail receptacle (11) on said trailing edge (9) by means of a roller; said guideline (12) is disposed along said headboard (10) so as to be able to move over at least one pulley between said trailing edge (9) and said leading edge (8). The element according to claim 1, characterized in that.

3. The guide line (12) is made of two parts, the first part on the side of the trailing edge (9) being fixed or movable by a pulley on the headboard (10) and movable by a roller in the receptacle (11), and the second part on the side of the leading edge (8) being fixed or movable by a pulley on the headboard (10) and movable by a roller in the receptacle (11), the element according to claim 1, characterized in that.

4. The element according to any one of claims 1 to 3, wherein the pulley limits friction as compared to a grommet.

5. The element according to claim 1, wherein at least two guide lines make it possible to improve the accuracy of the guide.

6. The element according to claim 1, wherein the guide line has a length of about 2 to 150 m for a sail of 10 to 1000 m2, preferably about 50 m for a sail of 100 m2.

7. The element according to claim 1, wherein the guide line (12) has a tension of 5 to 500 N for a sail of 10 to 1000 m2, preferably 50 to 250 N for a sail of 100 m2.

8. The element according to claim 1, wherein the sail comprises at least one reefing panel.

9. The element according to claim 1, wherein the sail comprises 0 to 10 reefing panels (20).

10. The element according to any one of claims 8 or 9, wherein each reefing panel (20) includes a reinforcing rib.

11. The element according to claim 1, wherein the mast (3) is fixed or telescopic.

12. A moving body for sail propulsion or hybrid propulsion, comprising at least one element according to claim 1, a hull, and a mast fixed to the hull but still rotatable, wherein the mast (3) is disposed within the cavity of the inflatable sail.

13. The moving body according to claim 12, wherein the sail (1) is oriented according to the wind direction and according to the traveling direction of the moving body manually or automatically.

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