Improved hydrofoil boat

Abstract

The boat comprises a hull (2), a first hydrofoil (301) fixed to the hull (2) by a first fixing device (302), and a second hydrofoil (601) fixed to the hull (2) by a second fixing device (503) separated from the first fixing device (302), the second fixing device including a strut (503) arranged to extend at least partially downwardly from the hull (2), the second hydrofoil being fixed to the strut. The boat comprises a motor pod (502) fixed to the strut (503), the strut and the motor pod being rotatable relative to the hull to steer the boat, the motor pod including a casing, a power assembly housed in the casing, and two propellers (5011, 5012) arranged to be driven by the power assembly, the two propellers (5011, 5012) being counter-rotating.

Description

[Technical Field]

[0001] The present invention relates to a boat comprising a hull, a first hydrofoil fixed to the hull by a first fixing device, and a second hydrofoil fixed to the hull by a strut separate from the first fixing device. [Background technology]

[0002] For example, internal combustion engines remain dominant in the propulsion of watercraft, such as pleasure craft, despite environmental and noise concerns. The engines may be, for example, inboard or outboard engines. The propulsion mode of a non-hydrofoil boat may be converted from displacement mode to planar mode if sufficient power capacity is available for its propulsion. Hydrofoils allow the boat to assume a propulsion mode. In hydrofoil mode, the hull is lifted out of the water, and compared to planar mode, the propulsion requirements are significantly lower, e.g., 50% less. Nevertheless, it is desirable to further reduce the propulsion requirements of boats. This can be done by reducing the boat's drag. Summary of the Invention

[0003] SUMMARY OF THE INVENTION An object of the present invention is to reduce the drag of a hydrofoil boat.

[0004] The object is achieved by a boat having a hull, the boat further comprising a first hydrofoil secured to the hull by a first securing device and a second hydrofoil secured to the hull by a second securing device separated from the first securing device. The second securing device includes a strut arranged to extend at least partially downward from the hull, and the second hydrofoil is secured to the strut. The boat includes a motor pod secured to the strut, the strut and motor pod being rotatable relative to the hull to steer the boat. The motor pod includes a casing, a power assembly housed in the casing, and two propellers arranged to be driven by the power assembly. The two propellers are counter-rotating.

[0005] The boat may thus be a hydrofoil boat. The motor pod allows for the omission of a mechanical power transmission assembly, such as a propeller shaft extending from the hull to the two propellers. Furthermore, the relatively low thrust requirements provided by the hydrofoil mode mean that the motor pod motor can be relatively small in volume while still providing sufficient thrust for this mode. This reduces the drag of the boat.

[0006] Also, the torque distributed to each of the two propellers, compared to a single propeller, makes a higher total torque, and thereby more thrust, available for propelling the boat.

[0007] Furthermore, the struts supporting the second hydrofoils can be relatively long and slender. The counter-rotation of the two propellers can cancel out the torques around the boat's rotation axis caused by the propellers. The rotation axis is understood to be an axis substantially parallel to the forward direction of the boat. The counter-rotation of the two propellers cancels out the torques of the two propellers, thereby reducing or eliminating the bending moment that would otherwise be caused by the propeller torque. This reduces the strength requirements of the struts, allowing them to be slender. This reduces the drag of the boat.

[0008] The prop and motor pod may also be rotated relative to the hull to steer the boat. In this manner, the prop with the motor pod and second hydrofoil is rotatable relative to the hull to steer the boat. By rotatable, the prop may be rotatable. With a single propeller, gyroscopic effects that occur when rotating the prop can cause deflection in the prop. Such deflection can be reduced by adding material or dimension to the prop. However, adding dimension adds drag. Using two counter-rotating propellers can counteract such gyroscopic effects and avoid the resulting prop deflection. This allows the prop to be kept slender, thereby keeping its drag low.

[0009] The first fixing device may include one, two, or more first struts, each extending from the hull to a first hydrofoil. The first hydrofoil may be fixed to the first fixing device. However, as exemplified below, the first hydrofoil is fixed relative to the first fixing device but is movable relative thereto.

[0010] The first hydrofoil may be the main hydrofoil, whereby the first hydrofoil may be adapted to carry the majority of the mass of the boat, hi some embodiments, the first hydrofoil is located at or near the center of gravity of the boat.

[0011] The second hydrofoil may be secured to a second securing device, which may include one or more struts extending between the hull and the second hydrofoil, such struts of the second securing device also being referred to herein as second struts.

[0012] Preferably, the second hydrofoil is positioned aft of the first hydrofoil when viewed in the forward direction of the boat. This may also be referred to as the aft hydrofoil. This allows the second fixing device to be positioned aft of the first fixing device when viewed in the forward direction of the boat. This provides a convenient position for the motor pod fixed to the second fixing device.

[0013] However, in some embodiments, the second fixing device may comprise a second hydrofoil, and the motor pod may be located forward of the first hydrofoil when viewed in the direction straight ahead of the boat.

[0014] The boat may be a pleasure boat, however, the boat may alternatively be adapted specifically for the transport of passengers and / or goods.

[0015] Preferably, the power assembly includes two electric motors housed coaxially within a casing. It is understood that, during use, the motor pod will be submerged in the water carrying the boat. Therefore, by locating the motors within the motor pod, noise levels can be reduced. The motors may also be effectively cooled by the surrounding water. Furthermore, electric motors can be relatively small compared to, for example, hydraulic motors, reducing the cross-sectional area of ​​the motor pod and thereby reducing drag.

[0016] Each of the two propellers can be arranged to be driven by a respective electric motor. Preferably, each of the two propellers is arranged to be driven directly by a respective electric motor without gearing. This eliminates the need for lubrication in the propeller drives, allowing for longer service intervals for the motor pod. The lack of gearing also allows for reduced noise levels and a less complex assembly for driving the propellers.

[0017] The two electric motors may be arranged one after the other in the longitudinal direction of the motor pod (i.e., in the direction of the rotation axis of the propellers). As mentioned above, the two propellers rotate in opposite directions.

[0018] The distribution of torque to two propellers reduces the torque demands on each motor, allowing for smaller motor sizes and therefore a smaller motor casing diameter. It also allows for smaller propeller diameters, allowing for higher rotational speeds and therefore a reduced motor torque demand without changing the available power, which allows for a smaller motor casing diameter.

[0019] Generally, one or more motors may be provided in the motor pod. In some embodiments, the power assembly includes a single electric motor arranged to drive both propellers, whereby one propeller may be provided with gearing for counter-rotation of the propeller. Preferably, when the casing has a cylindrical outer surface, the one or more motors are housed concentrically within the casing.

[0020] Optimizing the heat dissipation of the motors can increase the motor torque density, thereby further reducing the motor volume. Each motor may be a permanent magnet motor. The inner rotor of each motor may include a magnet, and the outer stator may include a heat-generating coil. The stator may be connected to the motor pod casing so that heat generated by the motor is conducted to the outer surface of the casing. This allows the heat to be transferred to the surrounding water. Preferably, the casing is made of a material with relatively high thermal conductivity, such as a metal such as bronze, brass, or stainless steel. This allows the casing to provide effective cooling of one or more motors by the surrounding water.

[0021] The diameter of each propeller is preferably in the range of 180 to 350 mm, for example, approximately 230 mm. When two propellers are provided, the total length of the propeller hubs is preferably in the range of 100 to 300 mm, preferably in the range of 130 to 250 mm, for example, approximately 180 mm. The casing preferably has a cylindrical outer surface. The entire casing can have a cylindrical outer surface, or one or more portions of the casing can have a cylindrical surface. The cylindrical outer surface of the casing preferably has a diameter in the range of 80 to 140 mm, for example, approximately 105 mm. The ratio of the length of the motor pod to the outer diameter of the casing is preferably at least 5, preferably at least 7, for example, approximately 9.5. The diameter of each motor is preferably in the range of 70 to 130 mm, for example, approximately 95 mm. The length of each motor is preferably in the range of 130 to 240 mm, for example, approximately 180 mm. This results in a relatively high length-to-diameter ratio of the motor, which reduces drag. Also, the relatively high ratio of exposed surface to motor volume allows for increased heat dissipation of the motor. Preferably, the ratio of the diameter of each motor to the outer casing diameter is at least 0.8, preferably at least 0.85, for example about 0.9.

[0022] Preferably, the length of the motor pod is in the range of 700 to 1400 mm, for example, approximately 1000 mm. Preferably, the ratio of the length of the motor pod to the outer diameter of the casing is at least 5, preferably at least 7, for example, approximately 9.5. Preferably, the ratio of the length of the motor pod to the outer diameter of the casing is 13 or less, preferably 17 or less. When two propellers are provided, it is preferable that the ratio of the combined length of the propeller hub to the length of the motor pod is in the range of 0.09 to 0.36, preferably in the range of 0.12 to 0.26, preferably in the range of 0.15 to 0.22.

[0023] Preferably, at cruising speed, the rotational speed of each motor is in the range of 1500 to 3500 rpm, for example around 2200 rpm. Preferably, the maximum torque of each motor is in the range of 60 to 130 Nm, for example around 90 Nm.

[0024] When the motor pod includes two motors, the motor shafts may be arranged concentrically, one inside the other. Preferably, the inner shaft has a diameter in the range of 14-28 mm, e.g., about 20 mm. Preferably, the outer shaft has a diameter in the range of 25-48 mm, e.g., about 35 mm.

[0025] The volume of an electric motor increases in proportion to the torque at a given magnetic load. Therefore, the volume of an electric motor increases in proportion to the maximum torque of the motor. Therefore, the hydrofoil mode with its relatively low power requirements allows for an electric motor with a relatively low volume. The small motor volume allows for a relatively low casing volume. Furthermore, a relatively long and slender motor, and / or motors arranged one after the other along the length of the motor pod, allows for a large distribution of the motor volume along the length of the motor pod, resulting in a relatively low cross-sectional area of ​​the motor pod. In a pushing configuration of the motor pod, this allows for a relatively small propeller diameter without the risk of flow disturbances at the propeller caused by the casing. A relatively small propeller diameter avoids the risk of cavitation of the propeller blade tips (which can occur at approximately 45 m / s). This allows for a relatively high Froude Number to be achieved with a relatively small amount of power. (The Froude Number, Fr, is given by Fr = v / (g·h) m ) 1 / 2 where v is the velocity, g is the gravitational acceleration, and h is the characteristic length.

[0026] As mentioned, the second fixing device includes a strut arranged to extend at least partially downward from the hull, and the second hydrofoil is fixed to the strut. The strut may extend substantially straight downward from the hull when the boat is floating upright. As mentioned above, the motor pod is fixed to the strut. The motor pod may be fixed to the strut at a lower end of the strut. Alternatively, the motor pod may be fixed to the strut above the lower end of the strut.

[0027] Preferably, the boat includes a prop mounting device for securing the prop to the hull, and the prop is pivotally connected to the prop mounting device by one or more prop bearings so that the prop can rotate relative to the hull. Therefore, the prop, together with the second hydrofoil and the motor pod, can rotate relative to the hull. This allows the boat to be steered by controlling the prop with the motor pod. The prop can rotate about an axis that is substantially parallel to a main extension of the prop. The rotation axis can be substantially vertical when the propulsion device is attached to the boat and when the boat is floating upright. Therefore, the prop can rotate relative to the hull about an axis that is substantially vertical when the boat is floating upright.

[0028] The struts may extend between one or more strut bearings and the motor pod in the range of 0.7 to 2.0 meters. Preferably, the ratio of the strut extension between one or more strut bearings and the motor pod, on the one hand, to the diameter of each propeller, on the other hand, is at least 2.0, preferably at least 3.9, preferably at least 5.7. Preferably, the ratio between the strut extension between one or more strut bearings and the motor pod, on the other hand, to the diameter of the cylindrical outer surface of the casing, on the other hand, is at least 5.0, preferably at least 8.0, preferably at least 14.0.

[0029] In some embodiments, the strut of the second securing device is tilted about an axis that is substantially horizontal when the boat is floating upright and that is substantially transverse to the boat's forward direction. The second hydrofoil may be fixed to the strut. The motor pod may be fixed to the strut. The strut may be tilted backward so that the strut can be tilted to reduce the boat's draft and / or to move the motor pod out of the water, for example, when docking. The tilt of the strut may also be used to trim the boat when running in extended hydrofoil mode.

[0030] In some embodiments, the strut of the second securing device is arranged to tilt about an axis that is substantially horizontal and substantially parallel to the direction of travel of the boat when the boat is floating upright.

[0031] Preferably, when the boat is floating upright, the second hydrofoil is positioned above the motor pod. This allows the second hydrofoil to be fixed to a strut between the motor pod and one or more strut bearings. The position of the second hydrofoil above the motor pod can have a beneficial effect on the propeller of the motor pod. The second hydrofoil can also prevent air from above the surface of the surrounding water from being sucked into the propeller. Preferably, the ratio of the vertical distance between the propeller rotation axis and the second hydrofoil, on the one hand, and the vertical distance between the propeller rotation axis and one or more strut bearings, on the other hand, is in the range of 0.09 to 0.19, preferably in the range of 0.12 to 0.16, e.g., 0.14.

[0032] In some embodiments, the second hydrofoil and the motor pod are at the same location along the strut.

[0033] The strut of the second securing device may include a lower strut portion and an upper strut portion, whereby the second hydrofoil may be attached to the strut between the lower strut portion and the upper strut portion. The lower strut portion may extend between the motor pod and the second hydrofoil. The second hydrofoil may be provided as a single component extending between the two wing tips. The second hydrofoil may extend spanwise between the wing tips, perpendicular to the boat's forward direction, and horizontally when the boat is at rest in an upright position. The second hydrofoil may extend at least partially through the strut. The second hydrofoil may be attached to the strut in the region between the wing tips, preferably centrally between the wing tips.

[0034] This can provide a rigid attachment of the second hydrofoil to the strut. In particular, the second hydrofoil can be attached to the strut between the lower strut section and the upper strut section, extending between the wing tips. The lower strut section can be made of the same material as the motor pod casing, such as a metal, e.g., bronze, brass, or stainless steel. The lower strut section and the casing can be formed in a single piece, e.g., by casting. This facilitates manufacturing of the interface between the strut and the casing. The upper strut section can be made of a different material than the lower strut section. For example, the upper strut section can be made of a fiber-reinforced plastic material, such as glass and / or carbon fiber-reinforced plastic material. This can provide the upper strut section with a high stiffness-to-weight ratio and / or a high strength-to-weight ratio. This can also facilitate maintenance and service of the motor pod, the strut, and / or the second hydrofoil. In particular, the lower strut section can be detached from the upper strut section to allow easy access to the second hydrofoil for replacement or repair.

[0035] The trailing edge of the strut preferably merges with the fin of the motor pod. The fin may gradually decrease in height toward the propeller. Preferably, the ratio of the horizontal extension of the fin to the maximum vertical extension of the fin is at least 1.5, more preferably at least 2.2, e.g., about 2.7. This allows the junction between the trailing edge of the strut and the motor pod to be parallel to the relative free flow of water over a relatively long distance. This avoids the risk of cavitation due to an increase in relative water velocity at the strut and therefore a decrease in pressure. In some embodiments, the ratio of the horizontal extension of the fin to the maximum vertical extension of the fin is preferably at least 3.0, at least 4.0, or at least 5.0.

[0036] Preferably, the motor pod is positioned so that when the boat is moving straight and the hull is carried by the first and second hydrofoils, it is lower in the water than the first hydrofoil, whereby the motor pod is positioned aft of the first hydrofoil and the water reaching the propeller may not be disturbed by the first hydrofoil.

[0037] Preferably, the first hydrofoil is a submerged hydrofoil. The second hydrofoil may also be a submerged hydrofoil. A submerged or submerged hydrofoil is a foil designed to be fully submerged in water during the boat's cruising mode. The submerged hydrofoil may have an adjustable pitch azimuth to vary the angle of attack of the foil. The submerged hydrofoil may be arranged to be controlled to present different lift coefficients and / or different angles of attack along its length for rotational stability of the boat. Rotation may be defined as movement about an axis of rotation that is substantially parallel to the forward direction of movement of the vessel. The axis of rotation may extend within the hull symmetry plane and may be substantially horizontal.

[0038] By making the first hydrofoil a submerged hydrofoil, the resistance of the podded electric boat is further reduced, thereby reducing the power required and allowing for a smaller motor housing diameter, further reducing resistance.

[0039] However, in some embodiments, the first hydrofoil type is a surface perforated hydrofoil. In some embodiments, the second hydrofoil type is a surface perforated hydrofoil.

[0040] Further advantages and advantageous features of the present invention are disclosed in the following description and in the dependent claims. [Brief explanation of the drawings]

[0041] [Figure 1] FIG. 1 shows a perspective view of a boat according to one embodiment of the present invention. [Figure 2] FIG. 2 shows a side view of the boat in FIG. [Figure 3] FIG. 3 is a front view of the boat of FIG. [Figure 4] 4A and 4B are diagrams showing vertical and longitudinal sections of the motor pod of the boat in FIG. [Figure 5] FIG. 5 is a diagram illustrating a side view of a boat according to an alternative embodiment of the present invention. [Figure 6] FIG. 6 is a diagram illustrating a side view of a boat according to an alternative embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0042] 1 to 3 show a hydrofoil boat 1. The boat comprises a hull 2. As shown in FIG. 3, the hull 2 ​​presents an imaginary vertical plane of symmetry SP and an imaginary horizontal plane HP that coincides with the waterline of the hull 2 ​​when the boat is stationary and floating.

[0043] The boat includes a first hydrofoil 301 fixed to the hull 2 ​​by a first fixing device 302. The first hydrofoil 301 is a submerged hydrofoil. The first hydrofoil 301 has an adjustable pitch azimuth angle so as to change the angle of attack of the first hydrofoil. The first hydrofoil 301 is connected to the hull by the first fixing device 302. The first fixing device 302 includes two wing retaining members 302. The wing retaining members 302 are in the form of struts, also referred to herein as first struts. The first hydrofoil 301 may be located approximately at the center of gravity CG of the boat 1 in the direction of travel of the boat 1, as illustrated in FIG. 2 .

[0044] In some embodiments, the boat does not include an adjustable hydrofoil.In some embodiments, the boat includes a surface perforating first hydrofoil.

[0045] The boat also includes a second hydrofoil 601. The second hydrofoil 601 is a submerged hydrofoil. The second hydrofoil is fixed to the hull 2 ​​by a second fixing device 503. The second fixing device 503 is separate from the first fixing device 302. The second fixing device includes a strut 503 arranged to extend downward from the hull 2. The second hydrofoil is fixed to the strut. The strut is fixed to the hull at the stern of the hull. The second hydrofoil is arranged aft of the first hydrofoil 301 when viewed in the forward direction of the boat. The second hydrofoil is arranged to support the aft part of the hull in hydrofoil drive mode.

[0046] The hull 2 ​​in this embodiment includes an aft extension 201. The strut 503 extends through an opening or recess (not shown) in the aft extension. In some embodiments, the strut 503 is mounted on the transom of the hull. In other embodiments, the strut extends through an opening in the hull between the stern of the boat and the first securing device 302.

[0047] The boat also includes a motor pod 502. The motor pod 502 is fixed to a support 503. The motor pod 502 is thus provided below the stern of the hull. When the boat is floating upright, the motor pod 502 is located below the second hydrofoil 601. The length MPL of the motor pod is 1000 mm in this example.

[0048] See also Figure 4. The motor pod comprises a casing 5021. The casing has a cylindrical outer surface. The diameter CD of the casing outer surface is 105 mm in this example. Two electric motors 5051, 5052 are housed coaxially within the casing. Two propellers 5011, 5012 are arranged to be driven by each of the motors. The diameter PD of the propellers 5011, 5012 is approximately 230 mm in this example. The propellers 5011, 5012 rotate counter-rotatingly. The propellers are located aft of the motors as viewed in the straight ahead direction of the boat. The propellers are pushing propellers. In some embodiments, the aft propeller may have a smaller diameter than the forward propeller. The propellers comprise blades mounted on a propeller hub. The composite length PHL of the propeller hub is approximately 240 mm in this example.

[0049] In some embodiments, the propeller is a pushing propeller, which means that the propeller is located forward of the motor when viewed in the direction of the boat's straight-on motion.

[0050] The motor is configured to be powered by a power source such as the battery pack 504 shown in Figure 2. Cables 506 for motor power and control are shown in Figure 4.

[0051] Each motor includes a stator 5071, 5072. The stators are fixed to the inner surface of the casing 5021. Each motor also includes a rotor 5081, 5082 fixed to each of two propeller shafts 5091, 5092. The inner shaft 5091 of the plurality of shafts connects a forward motor 5051 of the plurality of motors to a rearward propeller 5011 of the plurality of propellers. The outer shaft 5092 of the plurality of shafts connects a rearward motor 5051 of the plurality of motors to a forward propeller 5011 of the plurality of propellers. The inner shaft 5091 extends through the outer shaft 5092.

[0052] The diameter MD of each motor is 95 mm in this example. The length ML of each motor is 180 mm in this example. The inner shaft has a diameter of 20 mm in this example. The outer shaft has a diameter of 35 mm in this example.

[0053] In some embodiments, only one electric motor is housed within the casing and one propeller is configured to be driven by the motor.

[0054] The pole 503 holding the motor pod 502 is pivotally connected by one or more pole bearings 5033 to a pole mounting device 5034 so that the pole can rotate relative to the hull. The pole mounting device may be in the form of a bracket. The pole mounting device is preferably fixed to the hull. This allows the boat to be steered by controlling the pole carrying the motor pod. Preferably, the pole 503 extends 0.7 to 2.0 meters between the one or more pole bearings and the motor pod 502.

[0055] The strut 503 is arranged to tilt about an axis that is substantially horizontal when the boat is floating upright and that is substantially transverse to the direction of travel of the boat, allowing the strut to tilt clockwise or counterclockwise as seen in Figure 2.

[0056] As can be seen in FIG. 4 , the strut 503 includes a lower strut section 5031 and an upper strut section 5032. The lower strut section extends between the motor pod and the second hydrofoil 601. The second hydrofoil 601 is attached between the lower and upper strut sections. The second hydrofoil may be provided as a single component extending between the two wing tips. The second hydrofoil is attached to the strut in the central region between the wing tips. The second hydrofoil extends through the strut. The second hydrofoil is sandwiched between the strut sections. The strut may have a streamlined cross-section, such as an aerofoil-like cross-section, which may have a symmetrical shape. In this example, the rear of the second hydrofoil 601 is located behind the trailing edge of the strut 503. The lower strut section and / or the upper strut section may present respective protrusions 50311, 50321 for supporting the second hydrofoil. The protrusion may continue into the surface of the second hydrofoil in the chord direction of the second hydrofoil. The upper and lower strut portions may be fixed to each other and to the second hydrofoil in any suitable manner, for example by means of bolts and / or adhesive.

[0057] In some embodiments, a portion of the second hydrofoil 601 may extend aft and / or forward of the strut 503, such that the second hydrofoil may extend partially through the strut.

[0058] As shown in Figures 2 and 4, the trailing edge of the strut 503 merges into the fin 511 on the motor pod 502. The fin gradually decreases in height towards the propellers 5011, 5012. The ratio of the horizontal extension of the fin DFH to the maximum vertical extension of the fin DFV is approximately 6 in this example.

[0059] As can be seen from Figures 2 and 3, when the boat is moving straight and the hull 2 ​​is being carried by the first and second hydrofoils 301, 601, the motor pod 502 is positioned so that it is submerged more than the first hydrofoil 301.

[0060] One aspect of the present invention provides a boat according to any one of the following paragraphs:

[0061] (1) The boat Hull 2 ​​and a first hydrofoil assembly including a first hydrofoil 301 and a first fixing device 302, wherein the first hydrofoil 301 is fixed to the hull 2 ​​by the first fixing device 302; a second hydrofoil assembly separated from the first hydrofoil assembly and including a second hydrofoil 601 and a second fixing device 503, wherein the second hydrofoil 601 is fixed to the hull 2 ​​by the second fixing device 503; a motor pod 502 fixed to the first hydrofoil assembly or the second hydrofoil assembly; The motor pod includes a casing, a power assembly housed in the casing, and a propeller arranged to be driven by the power assembly.

[0062] (2) In the boat described in (1), The casing has a cylindrical outer surface; The ratio of the length MPL of the motor pod to the outer diameter CD of the casing is at least 5, preferably 7, for example around 9.5.

[0063] (3) In the boat according to (1) or (2), The diameter of the two propellers 5011, 5012 ranges from 180 to 350 mm.

[0064] (4) In the boat according to any one of (1) to (3), The ratio between the length MPL of the motor pod and the diameter MD of the propeller is at least 3.0, preferably at least 3.7, for example 4.3.

[0065] (5) In the boat according to any one of (1) to (4), The casing has a cylindrical outer surface with a diameter ranging from 80 to 140 mm.

[0066] (6) In the boat according to any one of (1) to (5), the power assembly includes one or more electric motors; The casing has a cylindrical outer surface; The ratio between the outer diameter CD of the casing and the diameter MD of each electric motor is less than or equal to 1.2, preferably less than or equal to 1.15, for example 1.1.

[0067] (7) In the boat according to any one of (1) to (6), The casing is made of bronze.

[0068] (8) In the boat according to any one of (1) to (7), the power assembly includes one or more electric motors; In each electric motor, the ratio between the motor length ML and the motor diameter MD is at least 1.4, preferably at least 1.7, for example 1.9.

[0069] (9) In the boat according to any one of (1) to (8), the power assembly includes one or more electric motors; The ratio between the length ML of each motor and the length MPL of the motor pod is at least 0.12, preferably at least 0.15, for example 0.18.

[0070] (10) In the boat according to any one of (1) to (9), The second securing device includes a post 502 positioned to extend at least partially downwardly from the hull; The second hydrofoil is fixed to the support.

[0071] (11) In the boat according to (10), The support post is located aft of the first fixing device when viewed from the direction of the boat's forward movement.

[0072] (12) In the boat according to (10), The support post is located forward of the first fixing device when viewed in the direction of the boat's forward movement.

[0073] (13) In the boat according to any one of (10) to (12), The motor pod 502 is fixed to a support 503 .

[0074] (14) In the boat according to any one of (1) to (12), The motor pod 502 is fixed to the first fixing device.

[0075] (15) In the boat according to any one of (1) to (14), The trailing edge of the strut 503 joins with the fin 511 of the motor pod 502, The ratio of the horizontal extension of the fin (DFH) to the maximum vertical extension of the fin (DFV) is at least 1.5.

[0076] When the stator of the motor is in contact with the casing, the ratio of the outer diameter CD of the casing to the diameter MD of each motor is 1.2 or less, so that the motor can be effectively cooled by the relatively thin wall of the casing.When the stator of the motor is in contact with the casing and the casing is made of bronze, which has a relatively high thermal conductivity, the casing can provide effective cooling for the motor.

[0077] An embodiment in which the second securing device comprises a strut 503 positioned aft of the first securing device as viewed from the straight ahead of the boat is shown in Figures 1-3. An embodiment in which the strut 503 is located forward of the first securing device 302 as viewed from the straight ahead of the boat is shown in Figure 5.

[0078] Regardless of whether the strut 503 is located aft or forward of the first fixing device, the boat may be provided with a strut mounting device 5034 for fixing the strut 503 to the hull 2, the strut being pivotally connected to the strut mounting device by one or more strut bearings 5033 so that the strut and motor pod can be rotated relative to the hull to steer the boat.

[0079] The strut 503 may extend 0.7 to 2.0 meters between one or more strut bearings and the motor pod 502. The strut may be positioned to tilt about an axis that is substantially horizontal when the boat is floating upright and that is substantially transverse to the boat's forward direction. When the boat is floating upright, the second hydrofoil 601 may be located above the motor pod 502. However, in some embodiments, the second hydrofoil 601 and the motor pod 502 are in the same position along the strut. The strut may include a lower strut section and an upper strut section, and the second hydrofoil is attached to the strut between the lower strut section and the upper strut section. The second hydrofoil 601 may be provided as a single component extending between the two wing tips.

[0080] It should be noted that within the scope of the paragraph, the second fixing device may comprise two or more struts for holding the second hydrofoil.

[0081] An embodiment in which the motor pod 502 is secured to the first hydrofoil 301 is illustrated in Figure 6. In some embodiments, for example, when the first securing device 302 comprises a single strut, the motor pod 502 may be secured to the strut.

[0082] It will be appreciated that the boat according to the above paragraphs can be implemented in various ways. For example, the power assembly can include two electric motors housed coaxially within a casing. Two propellers 5011, 5012 can be arranged to be driven by each of the motors. Each of the propellers 5011, 5012 can be arranged to be driven directly by each of the motors without a gearing. The motors can also be arranged one after the other in the longitudinal direction of the motor pod. This is illustrated in FIG. 4. The propellers 5011, 5012 preferably rotate in opposite directions.

[0083] However, in some embodiments, the motor pod may include a single propeller configured to be driven by a single motor.

[0084] The motor pod 502 may be positioned to be more submerged than the first hydrofoil 301 when the boat is moving straight ahead and when the hull 2 ​​is being carried by the first and second hydrofoils 301, 601. The first hydrofoil 301 and / or the second hydrofoil may be submerged hydrofoils.

[0085] The present invention is not limited to the embodiments described above and shown in the drawings, but rather, those skilled in the art will recognize that many variations and modifications may be made within the scope of the appended claims.

Claims

1. The hull (2) and a first hydrofoil (301) fixed to the hull (2) by a first fixing device (302); a second hydrofoil (601) fixed to the hull (2) by a second fixing device (503) separated from the first fixing device (302); Equipped with the second fixing device comprises a strut (503) arranged to extend at least partially downwardly from the hull (2); The second hydrofoil is fixed to the support. A boat, A motor pod (502) fixed to the support (503), the strut and the motor pod are rotatable relative to the hull to steer the boat; The motor pod includes a casing, a power assembly housed in the casing, and two propellers (5011, 5012) arranged to be driven by the power assembly; The two propellers (5011, 5012) are counter-rotating, the power supply assembly includes two electric motors housed coaxially within the casing; boat.

2. The second hydrofoil is located behind the first hydrofoil (301) when viewed from the straight ahead direction of the boat.

2. The boat of claim 1.

3. each of said two propellers (5011, 5012) is arranged to be driven by a respective electric motor; 3. A boat according to claim 1 or 2.

4. each of said two propellers (5011, 5012) being arranged to be directly driven by a respective electric motor without gearing; A boat according to any one of claims 1 to 3.

5. The two electric motors are arranged one after the other in the longitudinal direction of the motor pod. A boat according to any one of claims 1 to 4.

6. The casing is made of bronze. A boat according to any one of claims 1 to 5.

7. The diameter of the two propellers (5011, 5012) is in the range of 180 to 350 mm; A boat according to any one of claims 1 to 6.

8. The casing has a cylindrical outer surface with a diameter in the range of 80 to 140 mm. A boat according to any one of claims 1 to 7.

9. the casing has a cylindrical outer surface; The ratio of the motor pod length (MPL) to the casing outer diameter (CD) is at least 5; A boat according to any one of claims 1 to 8.

10. The second fixing device (503) is provided with a support mounting device for fixing the support (503) to the hull (2), the strut is pivotally connected to the strut mounting device by one or more strut bearings so that the strut and motor pod can rotate relative to the hull to steer the boat; A boat according to any one of claims 1 to 9.

11. the strut (503) extending between the one or more strut bearings and the motor pod in the range of 0.7 to 2.0 meters; 11. The boat of claim 10.

12. the struts are arranged to tilt about axes that are substantially horizontal and substantially transverse to the direction of travel of the boat when the boat is floating in an unheavy position; A boat according to any one of claims 1 to 11.

13. The second hydrofoil (601) is located above the motor pod when the boat is floating in a non-tilted state. A boat according to any one of claims 1 to 12.

14. the second hydrofoil (601) and the motor pod (502) are at the same position along the strut; A boat according to any one of claims 1 to 13.

15. the support column includes a lower support column portion and an upper support column portion; The second hydrofoil is attached to the support between the lower support portion and the upper support portion. A boat according to any one of claims 1 to 14.

16. the second hydrofoil (601) is provided as a single component extending between two wing tips; A boat according to any one of claims 1 to 15.

17. The trailing edge of the strut (503) merges with the fin (511) of the motor pod (502); The ratio of the horizontal extension of the fin (DFH) to the maximum vertical extension of the fin (DFV) is at least 1.5; A boat according to any one of claims 1 to 16.

18. When the boat is moving straight and the hull (2) is carried by the first hydrofoil (301) and the second hydrofoil (601), the motor pod (502) is positioned so as to be submerged in water more than the first hydrofoil (301). A boat according to any one of claims 1 to 17.

19. The first hydrofoil (301) is a submerged hydrofoil. A boat according to any one of claims 1 to 18.

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