Boat comprising engines that have propellers each positioned in a duct, ensuring optimised operation during forward travel and high manoeuvrability

Disclosed is a boat with at least one combustion engine positioned on or symmetrical with the vertical median plane of the boat and two engines provided symmetrical with respect to the vertical median plane, each including a propeller in a duct with: a central section on which the propeller is positioned, a rear section leading via a rear opening onto the transom of the hull, a front section with a continuous curved profile, leading via a side opening to the outside wall of the hull, the side opening having a larger cross-section than the cross-section of the rear opening in order for the duct to include at least one converging nozzle, the front section being oriented so that the stream of water exiting from the side opening is directed towards the front and forms an angle of 20° to 60° with respect to the wall of the hull.

This application relates to a boat that comprises drives that have propellers each positioned in a duct ensuring optimized operation when making headway and high maneuverability.

BACKGROUND OF THE INVENTION

The document FR-3,020,337 proposes a boat with hybrid propulsion that comprises a combustion drive and two electric drives placed on both sides of the combustion drive. Each electric drive comprises a propeller, positioned in a longitudinal duct, which extends from a water intake to a water outlet provided at the aft section of the boat. According to a special feature indicated in this document, each water intake is positioned in such a way as to be below the surface of the water when the boat sails at a speed below a given threshold and to be above the surface of the water when the boat lifts and sails at a speed in excess of the given threshold.

This embodiment is not completely satisfactory because it does not offer high maneuverability, in particular for carrying out certain maneuvers in port.

The document U.S. Pat. No. 5,090,929 proposes a boat equipped with two electric drives that are symmetrical relative to the median line of the hull and that each have a propeller positioned in a duct. Each duct comprises a first cylindrical and rectilinear section, which leads onto the transom of the boat and in which is positioned the propeller, as well as a second rectilinear section that leads, at a first end, onto the wall of the boat, and, at a second end, into the first section forward of the propeller. The second section leads onto the wall via louvered panels, oriented vertically, which orient the incoming stream of water in the direction of the propeller.

According to an embodiment, the boat comprises two drives at the bow for propelling the boat when making sternway and two drives at the aft section for propelling the boat when making headway.

According to this document, the electric drives are controlled by a single lever.

Even if this arrangement contributes to improving the maneuverability, the presence of four drives tends to complicate the boat design and therefore to increase its cost. According to another problem, the presence of the drives at the bow greatly tends to disrupt the flow of water along the hull when the boat is making headway and therefore to reduce the performance of the boat's propulsion system when making headway.

SUMMARY OF THE INVENTION

The purpose of this invention is to eliminate the drawbacks of the prior art.

For this purpose, the invention has as its object a boat that comprises at least one hull, a transom, at least two walls, as well as a propulsion system that comprises at least one internal combustion engine, positioned on or symmetrically relative to the vertical median plane of the boat, as well as at least two electric drives placed symmetrically relative to the vertical median plane and that each comprise a propeller placed in a duct that has:A central section on which the propeller is positioned,A rear section in the extension of the central section, which leads via at least one rear opening to the transom of the hull,A front section that leads via at least one side opening to a wall.

According to the invention, the duct has the following characteristics:The duct comprises at least one converging nozzle in the direction of a flow that passes from the side opening to the rear opening,The front section has a continuous curved profile, andThe front section is oriented in such a way that the stream of water exiting from the side opening is directed in a direction oriented toward the bow and forms an angle of between 20 and 60° relative to the wall.

The fact that the duct comprises at least one converging nozzle in the direction of a flow that passes from the side opening to the rear opening makes it possible to optimize the performance for a movement forward. The fact that the stream exiting from the side opening forms an angle of between 20 and 60° relative to the wall makes it possible, when a single electric motor propels a stream of water toward the bow, to create a resulting force that effectively makes the boat rotate, and, when the electric motors simultaneously propel streams of water toward the bow, to move the boat back effectively. Finally, the fact that the front section has a continuous curved profile makes it possible to reduce the pressure drops and to optimize performance regardless of the direction of travel.

According to other characteristics of the invention, the duct has at least one of the following characteristics:The rear section comprises a converging nozzle such that the rear opening has a passage cross-section that is smaller than the passage cross-section of the central section,The front section comprises a converging nozzle such that the side opening has a passage cross-section that is larger than the passage cross-section of the central section,The rear section comprises an extension that projects relative to the transom,The propeller has a diameter that is greater than or equal to 150 mm, preferably on the order of 300 mm,At least one deflector configured to limit the intake of the stream of water into the duct when the boat is making headway at high speed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to an embodiment provided by way of example that is non-limiting and shown inFIGS. 1 to 5, a catamaran-type boat comprises two hulls12.1and12.2, respectively called first and second hulls below, connected by a platform14.

Each hull12.1and12.2comprises a transom16.1and16.2, an outside wall18.1and18.2, and an inside wall20.1and20.2that meet at a forward point22.1and22.2.

The platform14comprises a bottom24that extends between the two hulls, a transom26placed approximately in the same plane as the transoms16.1and16.2of the hulls, as well as sides28.1and28.2that respectively top the outside walls18.1and18.2.

The elements of the hull of the boat10are symmetrical relative to a vertical median plane PMV that is shown inFIG. 5. Hereinafter, a longitudinal direction is parallel to the median plane PMV and the horizontal. A transverse plane is perpendicular to the longitudinal direction.

The invention is not limited to catamarans. Regardless of the embodiment, the boat10comprises at least one symmetrical hull relative to the vertical median plane, at least one transom, and two outside walls that are approximately parallel to the longitudinal direction at the aft section of the boat.

Preferably, the boat10comprises at least two hulls12.1,12.2that are tapered to obtain a deeper depression of the hulls12.1,12.2, as will be explained below.

The boat10comprises a waterline that corresponds to the intersection of the surface of the water and the hulls12.1and12.2when the boat is stopped or sails at a reduced speed, for example at a speed of less than 8 knots for a boat 9 m in length.

Hereinafter, for a hovercraft-type boat, high speed is defined as a speed higher than the minimum hydroplaning speed of the boat, and reduced speed is defined as a speed of less than the maximum hull speed of the boat.

The boat10comprises a propulsion system that comprises first and second electric drives30.1and30.2, placed symmetrically relative to the vertical median plane PMV, and an internal combustion engine32positioned on the vertical median plane PMV or symmetrically relative to the latter.

As a complement to the electric drives, the boat10comprises batteries for storing electrical energy.

According to a first configuration, the internal combustion engine32is of the outboard type and is attached to the transom26of the platform14.

According to another configuration that is shown inFIGS. 1 to 5, the internal combustion engine32is of the inboard type. In this case, it is positioned in part inside a central hull34positioned under the platform14, projecting relative to the bottom24, equidistant from the first and second hulls12.1and12.2.

This internal combustion engine32comprises an output shaft configured to drive a propeller in rotation. According to an embodiment, the output shaft is connected to the propeller by a first linkage that comprises a vertical shaft making it possible to direct the propeller to starboard or to port, and a second linkage that comprises a horizontal shaft making it possible to immerse the propeller or to take it all the way or part of the way out of the water. According to an embodiment, the internal combustion engine32is of the “Z-drive” type.

As a variant, the output shaft of the internal combustion engine32is stationary, and the boat comprises a rudder.

The internal combustion engine32is not presented in more detail because it is known to one skilled in the art.

As illustrated inFIGS. 7 and 12, each first and second drive30.1,30.2comprises an electric motor38operating in two directions, an output shaft40driven in rotation by the electric motor38, and a propeller42attached to the output shaft40.

Combined with the first and second drives30.1and30.2, the boat10comprises two ducts44that are symmetrical relative to the vertical median plane PMV, a first duct44placed in the first hull12.1and a second duct44in the second hull12.2when the boat is a catamaran.

As illustrated inFIGS. 6 to 10 and 12 to 14, each duct44has:A central section46, cylindrical (or non-cylindrical), on which the propeller42is positioned,A rear section48, rectilinear, in the extension of the central section46, which leads via at least one rear opening50to the transom16.1or16.2of the first or second hull12.1,12.2, andA front elbowed section52that leads via at least one side opening54to the outside wall18.1or18.2.

According to a characteristic, each duct44has a length, starting from the transom16.1,16.2of the boat, such that the side opening54is offset toward the aft section relative to the center of gravity of the boat. According to an embodiment, each duct44has a length, distance separating the side opening54from the transom16.1,16.2, of less than ¼ of the length of the boat (distance separating the bow and the stern of the boat). The length of the ducts44is to be the smallest possible to reduce the pressure drops and to increase the rotational torque when making sternway. By way of indication, for a boat of approximately 9 m, the side opening54is positioned at a small distance from the transom16.1,16.2, on the order of 1.3 m, less than 2 m.

The front section52is oriented in such a way that the stream of water exiting from the side opening54is directed in a direction F forming an angle of between 20 and 60° relative to the outside wall18.1or18.2and oriented toward the bow. Thus, the direction F is essentially perpendicular to the line passing approximately through the center of the side opening54and the center of gravity of the boat G, as illustrated inFIG. 4. The fact that the side openings are as far apart as possible relative to the center of gravity of the boat G and that the direction F is essentially perpendicular to the line passing approximately through the center of the side opening54and the center of gravity of the boat G makes it possible to increase the rotational torque. This characteristic makes it possible to offer high maneuverability to the boat that can rotate in place.

According to a characteristic of the invention, the central section46has a diameter that is greater than or equal to 150 mm. The diameter of the central section46is proportional to the dimension of the boat. The propeller has a diameter that is very slightly smaller than that of the central section. The larger the diameter of the propeller, the higher the propulsion output. Moreover, the diameter should not be too large so that the side and rear openings are immersed during the operation of the two electric drives30.1and30.2. For a 9 m boat, the propeller has a diameter that is greater than or equal to 150 mm, preferably on the order of 300 mm. This configuration makes it possible to produce a significant flow of water propelled by the propeller.

Each electric drive is preferably configured to operate in an optimal manner with a reduced rpm regime of the propeller, on the order of 1,500 rpm with ducts on the order of 300 mm in diameter and an approximately 9 m boat. This solution makes it possible to optimize the overall performance of the electric drives30.1and30.2that should operate at low pressure and high throughput.

According to another characteristic, the first and second drives30.1and30.2are configured to generate propulsion toward the bow when the propeller42rotates in a first direction of rotation and the water is ejected via the rear opening50, or propulsion toward the aft section when the propeller42rotates in a second direction of rotation (opposite to the first direction) and the water is ejected via the main side opening54.

To improve the performance of the propulsion system when making headway, the duct44comprises at least one converging nozzle in the direction of flow passing from the side opening54to the rear opening50. This converging nozzle makes it possible to optimize the performance when the boat is making headway.

According to a configuration, the rear section48comprises a converging nozzle56in such a way that the rear opening50has a passage cross-section S50that is smaller than the passage cross-section S46of the central section46. According to an embodiment, the converging nozzle56adjoins the rear opening50. This position makes it possible to produce an acceleration of the stream of water at the outlet and therefore a reduction in pressure to a value that is close to the water pressure outside of the duct44.

According to another configuration, the front section52comprises a converging nozzle56′, in the direction of flow passing from the side opening54to the rear opening50, in such a way that the side opening54has a cross-section S54that is larger than the passage cross-section S46of the central section46.

According to a configuration that is shown inFIGS. 7 and 8, the duct44comprises two converging nozzles in the direction of flow passing from the side opening54to the rear opening50, a first converging nozzle56between the central section46and the rear opening50, and a second converging nozzle56′ between the side opening54and the central section46. This double convergence makes it possible to achieve an acceleration of the stream of water downstream and upstream from the propeller42.

According to a configuration, the side opening54has a cross-section S54approximately whose surface is between 1.5 and 6 times the surface of the cross-section S50of the outlet opening50, ideally between 2 and 4 times the surface of the cross-section S50of the outlet opening50.

FIG. 11shows, by way of indication, the change in the cross-section of the duct44based on the distance between the cross-section that is provided and the side opening54, starting from the side opening54up to the transom. The curve L corresponds to the embodiment exhibiting the side opening54that is shown inFIG. 10.

Along the curve L, the duct44does not comprise any divergent portion.

According to a characteristic of the invention, the front section52has a continuous curved profile in the two directions of flow (from the side opening54to the rear opening50or from the rear opening50to the side opening54). As illustrated inFIGS. 7 and 8, this continuous curved profile makes it possible to reduce the pressure drops and to achieve an orientation of the stream exiting from the side opening that is optimal for maneuverability.

The side opening54has an approximately rectangular shape with a low height, less than 20 cm, and a great length, greater than 40 cm, as illustrated inFIGS. 9, 10, and 13. This configuration makes it possible to obtain a large cross-section while keeping the side opening54far away from the waterline when the drives30.1,30.2are operating.

According to another characteristic that is shown inFIGS. 6 to 8, the rear section48comprises an extension78that projects relative to the transom16.1,16.2. According to an embodiment, this extension78has a length—measured on the shaft of the duct44starting from the transom—that is greater than or equal to 10 cm. This solution makes it possible to keep the water from being released around the outlet opening50on the transom.

According to an embodiment that is shown inFIGS. 7 and 8, each transom16.1,16.2has a removable part80that comprises the first converging nozzle56and the extension78(in the case of a variant that comprises an extension78) to make it possible to access the propeller42and to be able to remove it.

According to a second embodiment, the front section52comprises a main side opening54and at least one secondary side opening. Thus, the duct44comprises at least one auxiliary section that leads, at a first end, into the central section46and/or the front section52forward of the propeller42, and, at a second end, via a secondary side opening to an inside wall18.1,18.2and/or outside wall20.1,20.2, offset toward the aft section relative to the main side opening54.

The front duct52has a larger radius of curvature than that of the auxiliary section. According to an embodiment that is shown inFIGS. 12 to 14, the duct44comprises at least one outside auxiliary section60that leads, at a first end, into the central section46and/or the front section52forward of the propeller42, and, at a second end, via an outside secondary side opening62to the outside wall18.1or18.2, offset toward the aft section relative to the main side opening54.

According to an embodiment, the duct44comprises at least one inside auxiliary section64that leads, at a first end65, into the central section46and/or the front section52forward of the propeller42, and, at a second end, via an inside secondary side opening66to the inside wall20.1and20.2, offset toward the aft section relative to the outside side secondary opening62.

According to an embodiment, the duct comprises at least one outside auxiliary section60and/or at least one inside auxiliary section64.

In the presence of secondary side openings, the main side opening has a cross-section that is smaller than the passage cross-section of the main section46. Thus, a converging nozzle58is obtained when the stream of water flows from the rear opening50to the side openings.

The sum of the cross-sections of the side openings54,62,66is greater than the cross-section S46of the central section46that is itself greater than the cross-section S50of the rear opening50. Thus, at least one converging nozzle is obtained when the stream of water flows from the side openings to the rear opening50.

When the propulsion system is making headway, at a reduced speed, the water penetrates the outside and inside secondary side openings62and66via the main side opening54, is propelled by the propeller42toward the aft section, and exits via the rear opening50.

When the propulsion system is making sternway, the water penetrates via the rear opening50, is propelled by the propeller42toward the bow, and exits almost exclusively via the main side opening54. Because of the continuity of the curvature of the front section52and/or because the front section52has a larger radius of curvature than that of the outside auxiliary section(s)60and the inside auxiliary section(s)64, almost no water flows into the outside auxiliary section(s)60and the inside auxiliary section(s)64.

According to another characteristic, the side openings54,62,66are designed in such a way as to reduce the perturbations at high speeds.

According to an embodiment that is shown inFIGS. 21 to 26, 27A to 27H, the body130comprises two hulls12.1and12.2that are symmetrical relative to the vertical median plane. These two hulls have a cross-section (perpendicular to the vertical median plane) that is tapered to obtain a depression of the hulls12.1and12.2ensuring an immersion of the ducts44when the boat advances at a low speed, for example in electrical operating mode.

Tapered is defined to mean that for each hull12.1,12.2, the ratio between a block coefficient and a prismatic coefficient R=As/(Bwl·T) is greater than 0.7, with As being the area of the largest immersed cross-section of the hull called amidships, Bwl being the width on the waterline of the amidships, and T being the height of the amidships.

According to another special feature, the amidships is positioned in a ⅓ aft section of the length of the boat.

According to another point, on the amidships, the minimal distance between the two hulls12.1,12.2on the waterline is greater than or equal to half the width of the boat.

As illustrated inFIG. 24, each hull12.1,12.2comprises an almost vertical bow132so as to maximize the waterline length.

For each hull12.1,12.2, the body130comprises an almost horizontal chine134(in a cross-section of the boat) with a dimension of approximately 50 mm. This chine134is positioned at mid-bow132, and then is offset to be positioned on the bottom136of each hull.

At the bow, the chine134is used as a deflector to channel the waves. On the aft section, as illustrated inFIG. 25, the chine134is used as a deflector and prevents the water from rising along the outside wall18.1,18.2when the boat advances at high speed, in particular in thermal operating mode.

The bow132has a step138that projects relative to a surface that is smaller by approximately 50 mm, so as to channel the waves that go beyond the chine134.

As illustrated inFIG. 23, the bottom136of each hull follows an evolving V, with the angle between the bottom136of the hull and the horizontal continuously changing all along the boat.

According to a special feature, the bottom136of each hull forms, at the bow of the boat, a first angle α1with the horizontal of greater than 60°, preferably on the order of 75°, which makes it possible to have inputs of spray to reduce water penetration resistance.

The bottom136of each hull forms, on the transom, a second angle α2with the horizontal of less than 20°, preferably on the order of 13°. This solution makes it possible to maximize the lift.

FIG. 26shows a body130with multiple transverse cutaways A to H that are shown inFIGS. 27A to 27H.

The gap between the lines of the keel Q12of the hulls12.1,12.2gradually increases from the bow to the aft section. The keel line Q34of the central hull34is always located above the line that passes through the keel lines Q12of the hulls12.1,12.2in the transverse planes. The passage cross-section of the water under the waterline at 3.5 t tends to increase from the bow to a cross-section that is located just forward of the side openings54and then decreases toward the stern.

According to an embodiment of the invention that is shown inFIGS. 9 and 13, each side opening54can comprise at least one deflector68that is configured to limit the intake of the stream of water70into the duct44when the boat is making headway at high speed and to avoid hindering the intake of water into the duct44when the boat operates at reduced speed.

According to an embodiment, the deflector68comprises a projecting shape relative to the outside wall18.1and18.2at the front of the main side opening54, as illustrated byFIGS. 12 and 13, and/or a recess relative to the outside wall18.1and18.2at the rear of the main side opening54, as illustrated inFIGS. 9 and 13.

According to an embodiment that is shown inFIGS. 12 to 14, each outside and/or inside secondary side opening62,66can comprise a deflector72, a projecting shape or a recess, configured to limit the intake of the stream of water70into the duct44when the boat makes headway at high speed with the internal combustion engine and to avoid hindering the intake of water into the duct44when the boat operates at reduced speed.

According to an embodiment illustrated inFIG. 15, the boat10comprises at least one master controller100whose inputs are connected to:A first heading control102configured to generate a heading command determined, for example, based on the angular position of a bar in the form of a steering wheel,A second acceleration control104configured to generate an acceleration command determined, for example, based on the angular position of a gas lever,A positioning sensor108of a cylinder (hydraulic or electric) that monitors the orientation of the base of the internal combustion engine32that supports the propeller.

According to another embodiment, in addition to the elements mentioned above, the boat10could comprise a third heading and/or acceleration control106configured to generate a heading and/or acceleration command determined, for example, based on the position of a “joystick”-type lever.

The second control104can comprise a single lever, as illustrated inFIG. 16, or a double lever, one for each electric motor, as illustrated inFIG. 15.

The outputs of the master controller100are connected to one of the electric drives30.1, to a slave controller110connected to another electric drive30.2, to an actuator112configured to monitor the internal combustion engine32, and to a proportional directional control valve114(in the case of a hydraulic cylinder) configured to monitor the position of the base of the internal combustion engine32that supports the propeller.

In hybrid operating mode, the master controller100can receive signals at these various inputs and can transmit signals via these various outputs. By way of example,FIG. 19illustrates the commands transmitted to the electric drives30.1and30.2, at reduced speed, based on the value of a heading command that varies from a minimal value to a maximal value, with the curve116corresponding to the values of the command transmitted to the electric drive30.1and the curve118corresponding to the values of the command transmitted to the electric drive30.2. According to thisFIG. 19, when the value of the command is less than 0, this corresponds to a direction of rotation of the electric drive that generates the propulsion of the stream of water toward the bow. At low speed, the steering of the electric motors makes it possible to enhance the maneuverability of the boat.

In electrical operating mode, as illustrated inFIG. 16, the master controller100can receive signals from the first heading control102and/or the second acceleration control104and emit signals in the direction of the first electric drive30.1and the slave controller110connected to the second drive30.2.

By way of example,FIGS. 17A and 17Billustrate the commands transmitted to the electric drives30.1and30.2based on the value of a heading command that varies from a minimal value to a maximal value, to produce a constant acceleration command value, with the latter having a first value inFIG. 17Aand a second value inFIG. 17B. The curves120and120′ correspond to the values of the command transmitted to the first drive30.1, and the curves122and122′ correspond to those transmitted to the second drive30.2.

FIG. 18shows the commands transmitted to the electric drives30.1and30.2based on the value of an acceleration command that varies from a minimal value to a maximal value, for a constant heading command value. The curve124corresponds to the value of the command transmitted to the first drive30.1, and the curve126corresponds to the one transmitted to the second drive30.2.

In electrical operating mode, the invention makes it possible—using only two electric drives30.1and30.2, by modulating the rpm and the direction of rotation of the propellers42of the first and second drives30.1and30.2independently of one another—to move the boat forward, backward, to starboard, to port, or to rotate.

As illustrated inFIG. 20A, when the internal combustion engine32is oriented to port and only the port electric drive30.1propels the water toward the bow, the boat10can turn to port.

As illustrated inFIG. 20B, when the port electric drive30.1propels the water toward the bow and the starboard electric drive30.2propels water toward the stern, the boat10can—based on the modes—turn to port by advancing, standing still, or moving back.

In electrical mode, the steering of the boat can be done in two ways:Either by directing the boat with a steering wheel and controlling its speed with a lever, as described above,Or by directing the boat and controlling its speed with two levers, one for each electric motor.