BOAT WITH ENGINES WHOSE PROPELLERS ARE EACH ARRANGED IN A CHANNEL, ENSURING OPTIMIZED OPERATION DURING FORWARD PROGRESS AND HIGH MANEUVERABILITY

Description

[0001] This application relates to a boat comprising motors which have propellers each positioned in a conduit providing optimized operation in forward gear and great maneuverability.

[0002] Document FR-3.020.337 proposes a hybrid propulsion boat that includes a combustion engine and two electric motors arranged on either side of the combustion engine. Each electric motor includes a propeller, positioned in a longitudinal duct, which extends from a water inlet to a water outlet provided at the rear of the boat. According to a feature indicated in this document, each water inlet is positioned so as to be below the water surface when the boat is sailing at a speed below a given threshold and to be above the water surface when the boat is planing and sailing at a speed above the given threshold.

[0003] This method of implementation is not fully satisfactory because it does not offer great maneuverability, particularly for carrying out certain maneuvers in port.

[0004] Document US-5,090,929 proposes a boat equipped with two electric motors, which are symmetrical with respect to the center line of the hull and which each have a propeller positioned in a conduit. Each conduit comprises a first cylindrical and rectilinear section, which opens at the transom of the boat and in which the propeller is positioned, as well as a second rectilinear section which opens, at a first end, at the wall of the boat and, at a second end, in the first section in front of the propeller. The second section opens at the wall via vertically oriented louvers, which direct the flow of incoming water towards the propeller.

[0005] According to one embodiment, the boat comprises two motors at the front for propelling the boat in reverse and two motors at the rear for propelling the boat in forward direction.

[0006] According to this document, electric motors are controlled by a single joystick.

[0007] Although this arrangement helps improve maneuverability, the presence of four engines tends to complicate the design of the boat and therefore increase its price. Another problem is that the presence of the engines at the front tends to strongly disrupt the flow of water along the hull when the boat is operating forward and therefore reduces the efficiency of the boat's propulsion system when moving forward.

[0008] The present invention aims to remedy the drawbacks of the prior art.

[0009] To this end, the invention relates to a boat comprising at least one hull, a transom, at least two walls and a propulsion system which comprises at least one thermal engine, positioned at or symmetrically relative to the vertical median plane of the boat, as well as at least two electric motors arranged symmetrically relative to the vertical median plane and which each comprise a propeller arranged in a conduit which has: a central section at which the propeller is positioned, a rear section in the extension of the central section, which opens via at least one rear orifice on the transom of the hull, a front section which opens via at least one lateral orifice on a wall.

[0010] According to the invention, the conduit has the following characteristics: the conduit comprises at least one convergent in the direction of a flow going from the side orifice towards the rear orifice, the front section has a continuous curved profile, and the front section is oriented so that the flow of water leaving the side orifice is directed in a forward-facing direction and forms an angle of between 20 and 60° relative to the wall.

[0011] The fact that the conduit includes at least one convergent in the direction of a flow going from the side orifice to the rear orifice makes it possible to optimize the efficiency for forward movement. The fact that the flow leaving the side orifice forms an angle of between 20 and 60° with respect to the wall makes it possible, when a single electric motor propels a flow of water forward, to create a resultant force which effectively turns the boat on itself and, when the electric motors simultaneously propel flows of water forward, to move the boat backward efficiently. Finally, the fact that the front section has a continuous curved profile makes it possible to reduce pressure losses and optimize the efficiency whatever the direction of movement.

[0012] According to other characteristics of the invention, the conduit has at least one of the following characteristics: the rear section comprises a convergent such that the rear orifice has a passage section smaller than the passage section of the central section, the front section comprises a convergent such that the side orifice has a passage section greater than the passage section of the central section, the rear section comprises an extension projecting from the transom, the propeller has a diameter greater than or equal to 150 mm, preferably of the order of 300 mm, at least one deflector configured to limit the suction of the water flow in the conduit when the boat is operating in forward gear at high speed.

[0013] Other characteristics and advantages will emerge from the description of the invention which follows, a description given by way of example only, with reference to the appended drawings, among which: There figure 1 is a perspective view, from a first angle of view, of a boat which illustrates an embodiment of the invention, The figure 2 is a perspective view, from a second angle of view, of the boat visible on the figure 1 , There figure 3 is a side view of the boat visible on the figure 1 , There figure 4 is a view from below of the boat visible on the figure 1 , There figure 5 is a rear view of the boat visible on the figure 1 , There figure 6 is seen in perspective from the rear of a boat which illustrates a first embodiment, The figure 7 is a cut, according to line VI-VI of the figure 5 , of a boat conduit with a flow of water flow towards the rear of the boat, The figure 8 is a cut, according to line VI-VI of the figure 5 , of a boat conduit with a flow of water flow towards the front of the boat, The figure 9 is a front view of a side orifice which illustrates an embodiment of the invention, The figure 10 is a front view of a side orifice which illustrates another embodiment of the invention, The figure 11 is a diagram showing the variation in the section of the conduit from the side inlet to the transom for the embodiments visible on the figure 10 , There figure 12 is a section of a ship's conduit which illustrates a second embodiment, The figure 13 is a perspective view of the duct openings visible on the figure 12 which open onto an exterior wall of the boat, The figure 14 is a perspective view of an orifice of the conduit visible on the figure 12 which opens onto an interior wall of the boat, The figure 15 is a diagram that illustrates the controls used to control the various engines of a boat in hybrid operating mode, The figure 16 is a diagram that illustrates the commands used to control the various motors in electric operating mode, The figures 17A et 17B are diagrams which illustrate the instructions transmitted to the right and left motors as a function of the variation of the steering instruction, for first and second constant values ​​of the acceleration instruction, in electric operating mode, The figure 18 is a diagram which illustrates the instructions transmitted to the right and left motors as a function of the variation of the acceleration instruction, for a constant value of the steering instruction, in electric operating mode, The figure 19 is a diagram which illustrates the instructions transmitted to the right and left motors as a function of the variation of the steering instruction, in hybrid operating mode, The figures 20A et 20B are top views of a boat that illustrate different examples of maneuvers, The figure 21 is a view of a hull of a boat from the front of the boat which illustrates an embodiment of the invention, The figure 22 is a bottom view of the hull visible on the figure 21 , There figure 23 is a longitudinal section between the hulls of the bottom of the hull visible on the figure 21 , There figure 24 is a side view of the bow of the hull visible on the figure 21 , There figure 25 is a cross-section at the level of the side orifices of the visible hull 21 which illustrates the deflection of the water in thermal operating mode, The figure 26 is a side view of the boat's hull visible on the figure 21 , and The figures 27A à 27H are sections of the hull respectively according to transverse planes A to H of the figure 26 .

[0014] According to an embodiment given as an example, non-limiting and visible on the figures 1 à 5 , a catamaran-type boat comprises two hulls 12.1 and 12.2, hereinafter called respectively the first and second hulls, connected by a platform 14.

[0015] Each hull 12.1 and 12.2 comprises a transom 16.1 and 16.2, an outer wall 18.1 and 18.2 and an inner wall 20.1 and 20.2 which meet at a forepeak 22.1 and 22.2.

[0016] The platform 14 comprises a bottom 24 which extends between the two hulls, a transom 26 arranged approximately in the same plane as the transoms 16.1 and 16.2 of the hulls as well as sides 28.1 and 28.2 which surmount the outer walls 18.1 and 18.2 respectively.

[0017] The elements of the hull of the boat 10 are symmetrical with respect to a vertical median plane PMV visible on the figure 5 . For the remainder of the description, a longitudinal direction is parallel to the median plane PMV and horizontal. A transverse plane is perpendicular to the longitudinal direction.

[0018] The invention is not limited to catamarans. Whatever the embodiment, the boat 10 comprises at least one hull symmetrical with respect to the vertical median plane, at least one transom and two external walls approximately parallel to the longitudinal direction at the rear of the boat.

[0019] Preferably, the boat 10 comprises at least two hulls 12.1, 12.2 tapered to obtain a greater sinkage of the hulls 12.1, 12.2, as will be explained later.

[0020] The boat 10 includes a waterline which corresponds to the intersection of the water surface and the hulls 12.1 and 12.2 when the boat is stationary or traveling at a reduced speed, for example at a speed of less than 8 knots for a boat 9 m long.

[0021] For the remainder of the description, for a planing type boat, high speed means a speed greater than the minimum hydroplaning speed of the boat and reduced speed means a speed lower than the maximum hull speed of the boat.

[0022] The boat 10 comprises a propulsion system which comprises first and second electric motors 30.1 and 30.2, arranged symmetrically with respect to the vertical median plane PMV, and a thermal engine 32 positioned at the level of the vertical median plane PMV or symmetrically with respect to the latter.

[0023] In addition to the electric motors, the boat 10 includes batteries to store electrical energy.

[0024] According to a first configuration, the thermal engine 32 is of the outboard type and fixed on the transom 26 of the platform 14.

[0025] According to another configuration visible on the figures 1 à 5 , the thermal engine 32 is of the in-board type. In this case, it is positioned partly inside a central hull 34 positioned under the platform 14, projecting relative to the bottom 24, equidistant from the first and second hulls 12.1 and 12.2.

[0026] This heat engine 32 comprises an output shaft configured to rotate a propeller. According to one embodiment, the output shaft is connected to the propeller by a first articulation, which comprises a vertical axis allowing the propeller to be oriented to the right or to the left, and a second articulation which comprises a horizontal axis allowing the propeller to be submerged or to be removed completely or partially from the water. According to one embodiment, the heat engine 32 is of the “Z drive” type.

[0027] Alternatively, the output shaft of the heat engine 32 is fixed and the boat includes a rudder.

[0028] The heat engine 32 is not described in more detail because it is known to those skilled in the art.

[0029] As illustrated on the figures 7 And 12, each first and second motorization 30.1, 30.2 comprises an electric motor 38 operating in both directions, an output shaft 40 driven in rotation by the electric motor 38 and a propeller 42 fixed on the output shaft 40.

[0030] Associated with the first and second engines 30.1 and 30.2, the boat 10 comprises two conduits 44 symmetrical with respect to the vertical median plane PMV, a first conduit 44 arranged in the first hull 12.1 and a second conduit 44 in the second hull 12.2 when the boat is a catamaran.

[0031] As illustrated on the figures 6 à 10 And 12 has 14 , each conduit 44 presents: a central section 46, cylindrical (or non-cylindrical), at the level of which the propeller 42 is positioned, a rear section 48, rectilinear, in the extension of the central section 46, which opens via at least one rear orifice 50 on the rear transom 16.1 or 16.2 of the first or second hull 12.1, 12.2, and a bent front section 52 which opens via at least one lateral orifice 54 on the external wall 18.1 or 18.2.

[0032] According to one feature, each conduit 44 has a length, starting from the transom 16.1, 16.2 of the boat, such that the side orifice 54 is offset rearward relative to the center of gravity of the boat. According to one embodiment, each conduit 44 has a length, distance separating the side orifice 54 from the transom 16.1, 16.2, less than 1 / 4 of the length of the boat (distance separating the bow and stern of the boat). The length of the conduits 44 must be as small as possible to reduce pressure losses and to increase the rotational torque when operating in reverse. As an indication, for a boat of approximately 9 m, the side orifice 54 is positioned at a short distance from the transom 16.1, 16.2 of the order of 1.3 m, less than 2 m.

[0033] The front section 52 is oriented so that the flow of water leaving the side orifice 54 is directed in a direction F forming an angle of between 20 and 60° relative to the outer wall 18.1 or 18.2 and oriented forward. Thus, the direction F is substantially perpendicular to the straight line passing approximately through the center of the side orifice 54 and the center of gravity of the boat G, as illustrated in the figure 4 . The fact that the side holes are as far apart as possible from the center of gravity of the boat G and that the direction F is substantially perpendicular to the straight line passing approximately through the center of the side hole 54 and the center of gravity of the boat G makes it possible to increase the rotational torque. This characteristic makes it possible to offer great maneuverability to the boat which can turn on the spot.

[0034] According to a characteristic of the invention, the central section 46 has a diameter greater than or equal to 150 mm. The diameter of the central section 46 is proportional to the size of the boat. The propeller has a diameter very slightly smaller than that of the central section. The larger the diameter of the propeller, the greater the propulsive efficiency. However, the diameter must not be too large so that the side and rear orifices are submerged during operation of the two electric motors 30.1 and 30.2. For a 9 m boat, the propeller has a diameter greater than or equal to 150 mm, preferably of the order of 300 mm. This configuration makes it possible to generate a significant flow of water propelled by the propeller.

[0035] Each electric motor is preferably configured to operate optimally at a reduced propeller rotation speed of around 1500 rpm with ducts of around 300 mm in diameter and a boat of around 9 m. This solution optimizes the overall efficiency of the 30.1 and 30.2 electric motors which must operate at low pressure and high flow.

[0036] According to another characteristic, the first and second motors 30.1 and 30.2 are configured to generate forward propulsion, when the propeller 42 rotates in a first direction of rotation and the water is ejected via the rear orifice 50, or backward propulsion when the propeller 42 rotates in a second direction of rotation (opposite to the first direction) and the water is ejected via the main lateral orifice 54.

[0037] To improve the efficiency of the propulsion system in forward operating mode, the conduit 44 comprises at least one convergent in the flow direction going from the side orifice 54 towards the rear orifice 50. This convergence makes it possible to optimize the efficiency in forward operating mode of the boat.

[0038] According to one configuration, the rear section 48 comprises a convergent 56 so that the rear orifice 50 has a passage section S50 smaller than the passage section S46 of the central section 46. According to one embodiment, the convergent 56 adjoins the rear orifice 50. This position makes it possible to obtain at the outlet an acceleration of the water flow and therefore a reduction in the pressure to a value close to the pressure of the water outside the conduit 44.

[0039] According to another configuration, the front section 52 comprises a convergent 56', in the direction of flow going from the lateral orifice 54 towards the rear orifice 50, so that the lateral orifice 54 has a section S54 greater than the passage section S46 of the central section 46.

[0040] According to a configuration visible on the figures 7 et 8 , the conduit 44 comprises two convergents in the direction of flow going from the lateral orifice 54 towards the rear orifice 50, a first convergent 56 between the central section 46 and the rear orifice 50 and a second convergent 56' between the lateral orifice 54 and the central section 46. This double convergence makes it possible to obtain an acceleration of the flow of water downstream and upstream of the propeller 42.

[0041] According to one configuration, the side orifice 54 has a section S54 approximately whose surface area is between 1.5 and 6 times the surface area of ​​the section S50 of the outlet orifice 50, ideally between 2 and 4 times the surface area of ​​the section S50 of the outlet orifice 50.

[0042] On the figure 11 , the variation of the section of the conduit 44 as a function of the distance between the given section and the lateral orifice 54 has been shown, starting from the lateral orifice 54 to the transom. Curve L corresponds to the embodiment having the lateral orifice 54 visible on the figure 10 .

[0043] According to curve L, conduit 44 does not include any diverging portion.

[0044] According to a characteristic of the invention, the front section 52 has a continuous curved profile in both flow directions (from the side orifice 54 to the rear orifice 50 or from the rear orifice 50 to the side orifice 54). As illustrated in the figures 7 et 8 , this continuous curved profile makes it possible to reduce pressure losses and to obtain an orientation of the flow at the outlet of the side orifice which is optimal for maneuverability.

[0045] The side orifice 54 has an approximately rectangular shape with a low height, less than 20 cm, and a long length, greater than 40 cm, as illustrated in the figures 9, 10 And 13 This configuration makes it possible to obtain a large section while keeping the lateral orifice 54 away from the waterline when the motors 30.1, 30.2 are operating.

[0046] According to another feature visible on the figures 6 à 8 , the rear section 48 comprises an extension 78 projecting relative to the transom 16.1, ,16.2. According to one embodiment, this extension 78 has a length, measured at the axis of the conduit 44 starting from the transom, greater than or equal to 10 cm. This solution makes it possible to avoid the detachment of water around the outlet orifice 50 at the transom.

[0047] According to an embodiment visible on the figures 7 et 8 , each transom 16.1, 16.2 has a removable part 80 which comprises the first convergent 56 and the extension 78 (in the case of a variant comprising an extension 78), to allow access to the propeller 42 and to be able to remove it.

[0048] According to a second embodiment, the front section 52 comprises a main lateral orifice 54 and at least one secondary lateral orifice. Thus, the conduit 44 comprises at least one auxiliary section which opens, at a first end, into the central section 46 and / or the front section 52 at the front of the propeller 42 and, at a second end, via a secondary lateral orifice on an inner wall 18.1, 18.2 and / or outer wall 20.1, 20.2, offset rearward relative to the main lateral orifice 54.

[0049] The front duct 52 has a larger radius of curvature than that of the auxiliary section. According to an embodiment visible on the figures 12 à 14 , the conduit 44 comprises at least one external auxiliary section 60 which opens, at a first end, into the central section 46 and / or the front section 52 at the front of the propeller 42 and, at a second end, via an external secondary lateral orifice 62 on the external wall 18.1 or 18.2, offset towards the rear relative to the main lateral orifice 54.

[0050] According to one embodiment, the conduit 44 comprises at least one internal auxiliary section 64 which opens, at a first end 65, into the central section 46 and / or the front section 52 at the front of the propeller 42 and, at a second end, via an internal secondary lateral orifice 66 on the internal wall 20.1 and 20.2, offset towards the rear relative to the external secondary lateral orifice 62.

[0051] According to one embodiment, the conduit comprises at least one external auxiliary section 60 and / or at least one internal auxiliary section 64.

[0052] In the presence of secondary lateral orifices, the main lateral orifice has a section smaller than the passage section of the main section 46. Thus, a convergent 58 is obtained when the flow of water flows from the rear orifice 50 towards the lateral orifices.

[0053] The sum of the sections of the lateral orifices 54, 62, 66 is greater than the section S46 of the central section 46 which is itself greater than the section S50 of the rear orifice 50. Thus, at least one convergent is obtained when the flow of water flows from the lateral orifices towards the rear orifice 50.

[0054] When the propulsion system is operating in forward gear, at a reduced speed, water enters via the main side port 54, the outer and inner secondary side ports 62 and 66, is propelled by the propeller 42 towards the rear and exits via the rear port 50. When the propulsion system is operating in reverse gear, water enters via the rear port 50, is propelled by the propeller 42 towards the front and exits almost exclusively via the main side port 54. Due to the continuity of the curvature of the front section 52 and / or the fact that the front section 52 has a larger radius of curvature than that of the outer auxiliary section(s) 60 and inner auxiliary section(s) 64, almost no water flows into the outer auxiliary section(s) 60 and the inner auxiliary section(s). 64.

[0055] According to another characteristic, the lateral orifices 54, 62, 66 are designed so as to reduce disturbances at high speeds.

[0056] According to an embodiment visible on the figures 21 à 26 , 27A à 27H , the hull 130 comprises two hulls 12.1 and 12.2 symmetrical with respect to the vertical median plane. These two hulls have a cross-section (perpendicular to the vertical median plane) tapered to obtain a sinking of the hulls 12.1 and 12.2 guaranteeing immersion of the conduits 44 when the boat is moving at a low speed, for example in electric operating mode.

[0057] By tapered, we mean that for each hull 12.1, 12.2, the ratio between a block coefficient and a prismatic coefficient R = As / (Bwl.T) is greater than 0.7, As being the area of ​​the largest submerged cross-section of the hull called the main frame, Bwl being the width at the waterline of the main frame and T being the height of the main frame.

[0058] According to another peculiarity, the master couple is positioned in a rear 1 / 3 of the length of the boat.

[0059] According to another point, at the level of the master couples, the minimum distance between the two hulls 12.1, 12.2 at the level of the waterline is greater than or equal to half the width of the boat.

[0060] As illustrated on the figure 24 , each hull 12.1, 12.2 includes a near-vertical bow 132 in order to maximize the waterline length.

[0061] For each hull 12.1, 12.2, the hull 130 comprises a quasi-horizontal chine 134 (in a cross-section of the boat) with a dimension of approximately 50 mm. This chine 134 is positioned at mid-bow 132 then shifts to be positioned at the level of the bottom 136 of each hull.

[0062] At the front, the 134 chine serves as a deflector to push back the waves. At the rear, as illustrated in the figure 25 , the chine 134 serves as a deflector and prevents water from rising along the outer wall 18.1, 18.2 when the boat is moving at high speed, particularly in thermal operating mode.

[0063] The stem 132 has a step 138 projecting from a lower surface by approximately 50 mm, in order to push back waves which exceed the chine 134.

[0064] As illustrated on the figure 23 , the bottom 136 of each hull describes an evolving V, the angle between the bottom 136 of the hull and the horizontal varying continuously along the entire length of the boat.

[0065] According to a particular feature, the bottom 136 of each hull forms, at the front of the boat, a first angle α1 with the horizontal greater than 60°, preferably of the order of 75°, which makes it possible to have fine water inlets to reduce the resistance of penetration into the water.

[0066] The bottom 136 of each hull forms, at the level of the transom, a second angle α2 with the horizontal less than 20°, preferably of the order of 13°. This solution makes it possible to maximize the lift.

[0067] On the figure 26 , a hull 130 has been represented with several cross sections A to H which are represented on the figures 27A à 27H .

[0068] The distance between the keel lines 0.12 of hulls 12.1, 12.2 increases progressively from front to rear. The keel line Q34 of the central hull 34 is always located above the line passing through the keel lines 0.12 of hulls 12.1, 12.2 in transverse planes. The water passage section below the waterline at 3.5 t tends to increase from the front to a cross section located just forward of the side openings 54 and then decreases to the rear.

[0069] According to an embodiment of the invention visible on the figures 9 And 13 , each side orifice 54 may comprise at least one deflector 68 configured to limit the suction of the water flow 70 into the conduit 44 when the boat is operating in forward gear at high speed and to not hinder the suction of water into the conduit 44 when the boat is operating at reduced speed.

[0070] According to one embodiment, the deflector 68 comprises a shape projecting from the outer wall 18.1 and 18.2 in front of the main side orifice 54, as illustrated by the figures 12 et 13 , and / or a recessed shape relative to the outer wall 18.1 and 18.2 at the rear of the main side orifice 54, as illustrated in the figures 9 And 13 .

[0071] According to an embodiment visible on the figures 12 à 14 , each external and / or internal secondary lateral orifice 62, 66 may comprise a deflector 72, projecting or hollow, configured to limit the suction of the water flow 70 in the conduit 44 when the boat is operating in forward gear at high speed with the thermal engine, and so as not to hinder the suction of water in the conduit 44 when the boat is operating at reduced speed.

[0072] According to an embodiment illustrated in the figure 15 , the boat 10 comprises at least one master controller 100 whose inputs are connected to: a first steering control 102 configured to generate a steering instruction determined for example as a function of the angular position of a bar in the form of a steering wheel, a second acceleration control 104 configured to generate an acceleration instruction determined for example as a function of the angular position of a throttle lever, a positioning sensor 108 of a cylinder (hydraulic or electric) controlling the orientation of the base of the thermal engine 32 supporting the propeller.

[0073] According to another embodiment, in addition to the elements mentioned above, the boat 10 could comprise a third steering and / or acceleration control 106 configured to generate a steering and / or acceleration instruction determined for example as a function of the position of a joystick type lever.

[0074] The second control 104 may comprise a simple joystick, as illustrated in the figure 16 , or a double lever, one for each electric motor, as shown in the figure 15 .

[0075] The outputs of the master controller 100 are connected to one of the electric motors 30.1, to a slave controller 110 connected to the other electric motor 30.2, to an actuator 112 configured to control the thermal engine 32 and to a proportional distributor 114 (in the case of a hydraulic cylinder) configured to control the position of the base of the thermal engine 32 supporting the propeller.

[0076] In hybrid operating mode, the master controller 100 can receive signals at these different inputs and can transmit signals via these different outputs. As an example, illustrated in the figure 19 the instructions transmitted to the electric motors 30.1 and 30.2, at reduced speed, as a function of the value of a steering instruction varying from a minimum value to a maximum value, the curve 116 corresponding to the values ​​of the instruction transmitted to the electric motor 30.1 and the curve 118 corresponding to the values ​​of the instruction transmitted to the electric motor 30.2. According to this figure 19 , when the setpoint value is less than 0, this corresponds to a direction of rotation of the electric motor which generates propulsion of the water flow forward. At low speed, the control of the electric motors makes it possible to improve the maneuverability of the boat.

[0077] In electric operation mode, as shown in the figure 16 , the master controller 100 can receive signals from the first steering control 102 and / or from the second acceleration control 104 and transmit signals towards the first electric motor 30.1 and the slave controller 110 connected to the second motor 30.2.

[0078] As an example, we have illustrated on the figures 17A et 17B the instructions transmitted to the electric motors 30.1 and 30.2 as a function of the value of a steering instruction varying from a minimum value to a maximum value, for a constant acceleration instruction value, the latter having a first value on the figure 17A and a second value on the figure 17B Curves 120 and 120' correspond to the setpoint values ​​transmitted to the first motor 30.1 and curves 122 and 122' to those transmitted to the second motor 30.2.

[0079] On the figure 18 , the instructions transmitted to the electric motors 30.1 and 30.2 are represented as a function of the value of an acceleration instruction varying from a minimum value to a maximum value, for a constant steering instruction value. Curve 124 corresponds to the value of the instruction transmitted to the first motor 30.1 and curve 126 to that transmitted to the second motor 30.2.

[0080] In electric operating mode, the invention makes it possible, using only the two electric motors 30.1 and 30.2, by modulating the rotation speed and the direction of rotation of the propellers 42 of the first and second motors 30.1 and 30.2 independently of each other, to move the boat forward, backward, to the right, to the left or to turn on the spot.

[0081] As illustrated on the figure 20A , when the thermal engine 32 is oriented to the left and only the left electric motor 30.1 propels the water forward, the boat 10 can turn to the left.

[0082] As illustrated on the figure 20B , when the left electric motor 30.1 propels the water forward and the right electric motor 30.2 propels the water backward, the boat 10 can, depending on the speed, turn left while moving forward, staying in place or backward.

[0083] In electric mode, the boat can be piloted in two ways: either by steering the boat with a steering wheel and controlling its rpm with a joystick, as described above, or by steering the boat and controlling its rpm with two joysticks, one for each electric motor.

Claims

1. Boat that comprises at least one hull (12.1, 12.2), a transom (16.1, 16.2), at least two walls (18.1, 18.2), as well as a propulsion system that comprises at least one internal combustion engine (32), positioned on or symmetrically relative to a vertical median plane of the boat, and at least two electric drives (30.1, 30.2) placed symmetrically relative to the vertical median plane and that each comprise a propeller (42) placed in a duct (44) that has: - a central section (46) on which the propeller (42) is positioned, longitudinally oriented, - a rear section (48) in the extension of the central section (46), which leads via at least one rear opening (50) to the transom (16.1, 16.2) of the hull (12.1, 12.2), - a front section (52) that leads, via at least one side opening (54), to the wall (18.1, 18.2), characterized in that the side opening (54) has a cross-section that is larger than the cross-section of the rear opening (50) so that the duct (44) comprises at least one converging section, in that the front section (52) is bent and has a curved profile, and in that the front section (52) is oriented in such a way that the stream of water exiting from the side opening (54) is directed in a forward direction and forms an angle of between 20 and 60° relative to the wall (18.1, 18.2).

2. Boat according to Claim 1, characterized in that the propeller (42) has a diameter that is greater than or equal to 150 mm, preferably on the order of 300 mm.

3. Boat according to one of the preceding claims, characterized in that the side opening (54) has an approximately rectangular cross-section (S54) that has a surface of between 2 and 4 times the surface of the cross-section (S50) of the outlet opening (50).

4. Boat according to one of the preceding claims, characterized in that each duct (44) has a length of less than ¼ of the length of the boat.

5. Boat according to one of the preceding claims, characterized in that the rear section (48) comprises a converging nozzle and in that the front section (52) comprises a converging nozzle.

6. Boat according to one of the preceding claims, characterized in that the hull comprises at least one deflector (72) configured to limit the intake of the stream of water (70) into each duct (44) when the boat is making headway at high speed.

7. Boat according to one of the preceding claims, characterized in that the rear section (48) comprises an extension (78), projecting relative to the transom (16.1, 16.2), which has a length, measured on the shaft of the duct (44) starting from the transom, that is greater than 10 cm.

8. Boat according to one of the preceding claims, with said boat comprising at least two hulls (12.1, 12.2), symmetrical relative to a vertical median plane, connected by a platform (14) that has a bottom (24), with each of the hulls (12.1, 12.2) comprising a transom (16.1, 16.2), an outside wall (18.1, 18.2), and an inside wall (20.1, 20.2), characterized in that each hull (12.1, 12.2) has a cross-section that is tapered to obtain a depression of the hulls (12.1 and 12.2) and to ensure an immersion of the ducts (44) when the boat advances at low speed.

9. Boat according to the preceding claim, characterized in that it comprises a central hull (34), positioned under the platform (14), projecting relative to the bottom (24), equidistant from the first and second hulls (12.1, 12.2), with the keel line (Q34) of the central hull (34) always being located above the line that passes through the keel lines (Q12) of the first and second hulls (12.1, 12.2) in the transverse planes.

10. Boat according to Claim 8 or 9, characterized in that each hull comprises a ratio between a block coefficient and a prismatic coefficient R = As / (Bwl.T) that is greater than 0.7, with As being the amidships, Bwl being the width on the waterline of the amidships, and T being the height of the amidships.

11. Boat according to one of Claims 8 to 10, characterized in that on the amidships, the minimal distance between the two hulls (12.1, 12.2) on the waterline is greater than or equal to half the width of the boat.

12. Boat according to one of Claims 8 to 11, characterized in that for each hull, the amidships is positioned in a 1 / 3 aft section of the length of the boat.

13. Boat according to one of Claims 8 to 12, characterized in that the bottom (136) of each hull (12.1, 12.2) forms a first angle (α1) with the horizontal of greater than 60°, preferably on the order of 75°, on the bow of the boat.

14. Boat according to the preceding claim, characterized in that the bottom (136) of each hull (12.1, 12.2) forms, on the transom, a second angle (α2) with the horizontal of less than 20°, preferably on the order of 13°.

15. Boat according to one of Claims 8 to 14, characterized in that for each hull, the side opening (54) has an approximately rectangular shape with a low height, less than 20 cm, and a great length, greater than 40 cm.