Patent Description:
A sailing hydrofoil is a wing-like structure mounted under the hull of a boat, such as a yacht, that provides a speed advantage over more traditional boat designs. The sailing hydrofoil works with its wing-like appendage. Just like a wing on an aircraft provides lift, a hydrofoil in the water accomplishes the same thing. The main difference is that a hydrofoil does not need to be as large as an airplane wing, because the water is much denser than air. As the boat increases its speed the hydrofoils lifts most of the hull, or even the entire hull, up and out of the water, greatly reducing the wetted area, resulting in decreased drag and increased speed as the craft cuts through the water.

Most types of boats can accommodate hydrofoils, and sailboats are no different. A sailing hydrofoil could be a single hull, often referred to as a mono hull, a catamaran (which has two hulls), or a trimaran (which has three hulls). In the case of multiple hulls, the hulls are held together by a single upper deck. The wider and longer the ship, the more stable the sailing hydrofoil is.

Conventional hydrofoils are used in either a passive way i.e. there is no active control on their geometry, or in an active way i.e. using flaps to cause the craft to ascend or descend and to control the craft about its pitch, heave, and roll axes. However, all control is manual e.g. using a control system with a mechanical lever arm, and the flaps require human intervention, which inherently requires extensive experience by a user and exposes the craft control to human error. In the same way as for aircraft, there is an inherent trade-off between a requirement for faster and more accurate control and overall drag (a lower drag foil will come at the cost of inherent stability).

Hydrofoil water vessels may be wind powered (e.g. yachts, sailing boats), or powered using an engine and gearbox mounted on the hull and mechanically engaged with a propeller system mounted adjacent the foil on the underside of the hull. There are obvious drawbacks to this arrangement including efficiency losses due to mechanical distance between the engine/gearbox and the propeller system.

However, it is not practical for the engine to be located beneath the hull because of additional hydrodynamic drag due to mechanical linkage between engine, gearbox and propeller (propeller shaft, bearings). It also creates a challenge for the system integrity as the foils deform under hydrodynamic loading.

There is therefore a need for an improved engine and gearbox arrangement that increases efficiency and reduces delay and energy loss via mechanical connections and results in a reduction in overall fuel/energy usage, while minimizing the packaging, to reduce hydrodynamic drag. <CIT> discloses a boat, partially supported by a pair of asymmetric hydrofoil assemblies. Each hydrofoil assembly is generally L-shaped and including a motor and propeller connected to one end of an associated hydrofoil and to one end of a mounting leg having its other end connected to the watercraft at a location spaced from the other hydrofoil assembly thus defining the asymmetric hydrofoils. A driven propeller is located in alignment with an angle joint between a supporting leg and the associated hydrofoil, and is driven in a direction wherein upwardly moving blades of a propeller intercept a downwardly moving water wake of the vehicle and also water downwash flowing past the trailing edges of the associated asymmetric hydrofoils.

<CIT> discloses a watercraft device that comprises a board, a throttle coupled to a top surface of the board, a hydrofoil coupled to a bottom surface of the board, and an electric propeller system coupled to the hydrofoil. The electric propeller system powers the watercraft device using information generated from the throttle.

<CIT> discloses a hydrofoil system having a fuselage with a propeller mounted to one end of the fuselage and a wing extending laterally from the fuselage. The fuselage is configured for removable attachment to a mast, so that the mast when attached extends from the fuselage in a direction substantially orthogonal to the longitudinal axis and also substantially orthogonal to the wing. A tail wing is connected to the fuselage by a tail strut, so that the tail wing is positioned beyond the end of the fuselage to which the propeller is attached. A motor is housed in the fuselage and has a cable connected thereto, the cable extending outside the fuselage, wherein a removable sealing system inhibits water ingress to the motor at the location where the cable is connected when the sealing system is installed in the fuselage.

<CIT> discloses an electric motor for trolling at slow speeds comprising an elongated and generally cylindrical submersed unit which houses an electric motor that in turn drives a planetary gear system that in turn drives the propeller. The planetary gear system includes a compact gear assembly which can be assembled ahead of time and quickly inserted in the gear housing. The internal gear ring of the planetary gear system is quickly and easily secured within and to the gear housing only and by means of cap bolts extending through the gear housing and into engagement with the ring gear, the ring gear being preassembled in the gear housing. The motor also includes a bearing support in which are preassembled anti-friction bearing assemblies. A rear sleeve thrust bearing and a front sleeve thrust bearing are located on opposite sides of the gear assembly and act to threadably support the gear assembly and absorb axial thrust.

The present invention seeks to address the problems of the prior art. Aspects of the present invention are set out in the attached claims. The invention is defined by the independent claims, to which reference should now be made. Preferred features are set out in the dependent claims.

A first aspect of the present invention provides a boat including a hydrofoil system as in claim <NUM>.

By locating the gearing system and engine within a housing provided at least in part by the hydrofoil, the profile of the gearbox system is significantly reduced. This layout significantly reduces the wetted area of the drive train, therefore reducing hydrodynamic drag of the eFoil system, improving efficiency and autonomy.

In an alternative embodiment, the gearbox system is mounted on the hydrofoil. This allows the gearbox system to be completely separated from the Foil, allowing for Drive train fast replacement in case of maintenance, therefore minimizing downtime for commercial vessels.

In one embodiment, the gearing system and engine are a close fit within the interior space of the housing.

The close fit allows the engine and gearbox to be in thermal contact with the gearbox casing such that heat generated by the engine and/or gearbox during use may be transferred by contact to the gearbox casing, which is subsequently cooled by the surrounding water in which it is submerged. No mechanical or forced water flow is required to cool the engine and gearbox.

Preferably, the engine is located adjacent the gearbox. The gearbox casing forms part of the foil and locates the engine to the foil structure.

The gearbox casing is thermally conductive in order to cool the engine and gearbox by heat transfer into the surrounding environmental water. Preferably, the gearbox casing comprises metal, and preferably coated or non-corrosive/corrosive resistant raw metal. However, it is to be appreciated that any suitable known to the skilled person and highly resistant to corrosion could be used as an alternative to, or in addition to, using metal for the gearbox casing.

In a further embodiment, the gearbox housing further comprises a power train engagement portion. In use, the power train engagement portion engages with a power train connected to the controller on the hull of the vessel. This provides electrical communication between the controller and the engine and gearbox.

Preferably, the power train engagement portion is located distal to the propeller shaft engagement portion. This prevents any fouling of the power train by the moving parts of the propeller.

According to the invention, the gearing system is an epicyclic gearbox (also known as planetary gearbox). However, it is to be appreciated, that any other suitable reduction system known to the skilled person and suitable for function could be used in addition to an epicyclic gearbox.

In a further embodiment, the engine comprises a high-power density electrical engine, referred to as a Motor Generator Unit (MGU).

Thus, the engine may comprise an MGU and the gearbox may include epicyclic reduction hardware, both being located within the watertight gearbox casing.

The gearbox casing may comprise, but is not limited to, any one or more of the following materials, including stainless steel (all grades), titanium alloy, aluminium (aluminum). However, it is to be appreciated that any other suitable material known to the skilled person may be used to make up the gearbox casing. Preferably, an appropriate sea water coating is applied to the gearbox casing to render the gearbox more resistant to sea water erosion.

It is to be appreciate that any other material known to the skilled person and suitable for function may be used in addition to, or as an alternative to, the aforementioned materials. Such other materials may include, but are not limited to, one or more of a composite material such as Aramid fibre, or carbon fibre reinforced resin material.

According to the invention, the boat further includes a hydrofoil system, the hydrofoil system comprising a controller; a foil for engagement with the waterborne vessel, the foil comprising a plurality of adjustment members operable to vary the lift characteristics of the waterborne vessel; a propeller mounted on the foil; and the above described gearbox system, wherein the propeller is mechanically engaged with the propeller shaft engagement portion and the gearbox system is in mechanical communication with the propeller.

In one embodiment, the hydrofoil system further comprises a plurality of sensors in electrical communication with the controller, each sensor configured to monitor flight parameters of the waterborne vessel and generate measured flight parameter data, wherein the controller is in communication with the adjustment members, the engine and the sensors and wherein the controller is configured to receive measured flight parameter data from the sensors and to control the operation of the engine and the position of the adjustment members in dependence upon the received measured flight parameter data.

In one embodiment, each of the adjustment members is operable to vary one or more of pitch, roll, heave, and yaw of the waterborne vessel.

In one embodiment, each adjustment member comprises a flap and an actuator, wherein the flap is moveable relative to the foil on activation of the actuator by the controller. Preferably, the adjustment member further comprises a hydrodynamic fairing within which the flap is arranged.

Preferably, the actuators are integrated within the foil. However, it is to be appreciated that the actuators may alternatively be integrated inside the vessel, depending on the respective sizes of the foil and vessel.

In one embodiment, each of the plurality of flaps is independently adjustable. This provides greater control over the position of the vessel within the water.

In a further embodiment, the plurality of flaps comprises at least one set of two aligned flaps. However, additional flaps may be provided within each set of flaps if required.

Preferably, the propeller is located adjacent to the gearbox, and distal to the engine. Preferably, the propeller is located adjacent to the gearbox, and distal to the engine, via a short propeller shaft, in order to minimise efficiency loss.

As with conventional foils, each foil of the present invention is composed of two lifting surfaces: the elevator (horizontal part) which provides vertical lift; and a shaft, whose main purpose is to carry the elevator and also provide side force in turns and manoeuvres.

The measured flight parameter data may comprise any one or more selected from the group comprising acceleration data, vessel position data (pitch, heave, yaw, roll), actuator positional data, external environmental factors (e.g. wind, wave-height) and any other useful data relating to the movement of the vessel through the water, and the environment the vessel is moving in.

Preferably, the controller is located within the hull of the waterborne vessel and the foil is located beneath the floating waterline on the hull exterior of the waterborne vessel.

In a further embodiment, the hydrofoil system further comprises a battery system in electrical communication with the engine and optionally the actuator, wherein the battery system is operable to provide power to the engine and optionally the actuator. Alternatively, the adjustment member may be actuated using hydraulic power. Such a battery system may comprise a Power Electronics Control Unit (PECU). It is to be appreciated that the boat including a hydrofoil system may be provided integrally as part of a new vessel during manufacture, or may be provided for retrofit to an existing vessel. In both cases, the vessels will then have all the advantages provided by the hydrofoil system. Such advantages include:.

Thus, the boat including a hydrofoil system of the present invention provides a high efficiency and low consumption propulsion system for high speed marine travel whilst providing autonomous control of a fully submerged actively controlled foiling waterborne vessel.

<FIG> shows a waterborne vessel in the form of a monohulled vessel <NUM> provided with an embodiment of a hydrofoil system in accordance with a first embodiment of the present invention. The hydrofoil system comprises a controller <NUM> located within the hull <NUM> of vessel <NUM>.

A battery system <NUM> is located adjacent controller <NUM>, and in electrical communication with controller <NUM>. In the embodiment of <FIG>, battery system <NUM> comprises a Power Electronics Control Unit (PECU).

A foil <NUM> is located on the outer surface of the foil hull below the floating waterline. Foil <NUM> comprises a plurality of adjustment members <NUM> operable to vary the lift characteristics of the vessel <NUM> during travel. Each adjustment member comprises a flap <NUM> and associated actuator <NUM>. Actuators <NUM> can be either electric or hydraulic and may be integrated within foil <NUM> (as shown in <FIG>) or may be located within the vessel <NUM> itself depending on the vessel size and associated foil size. Actuators <NUM> operate to control the position of associated flaps <NUM> to control the ship in heave i.e. ride height <NUM> relative to the floating water line <NUM>), pitch, roll and thrust. Ride height <NUM> is shown in <FIG> and is based on the distance between the water surface (floating water line <NUM>) and the foiling water line <NUM>. Foiling water line refers to where the water free surface sits, relative to the foils/hull, while airborne. When the boat is floating, the water line is defined by how much the hull needs to sink to obtain the volume of displacement (under Archimedean hydrostatic force). When foiling, the foiling water line is the optimum between minimum foil immersion ( the vertical part "shaft") to reduce drag without having the elevator <NUM> ventilating because of the free surface proximity.

In the embodiment of <FIG>, the adjustment member <NUM> further comprises a hydrodynamic fairing <NUM> within which the flap <NUM> is arranged.

In <FIG>, each foil comprises four flaps <NUM>, each flap <NUM> is independently operable by an associated actuator <NUM>.

Foil <NUM> is connected to the hull <NUM> of vessel <NUM> by means of a vertical shaft <NUM>.

A propeller <NUM> is mounted on foil <NUM> for driving the vessel <NUM> through the water during travel. The propeller <NUM> and foil <NUM> are shown in more detail in <FIG>.

In disclosed but not claimed a first embodiment shown in <FIG> and <FIG>, foil <NUM> comprises a body <NUM> defining an elongate channel <NUM>. Elongate channel <NUM> has a first open end <NUM> and a second end <NUM> opposing the first end <NUM>, first and second ends <NUM>, <NUM> being in fluid communication with one another. Propeller <NUM> is mounted on the foil at the second end <NUM> of channel <NUM>.

An engine <NUM> and aligned gearbox <NUM> are mounted within elongate channel <NUM> and mechanically coupled to propeller drive shaft <NUM>. At a first end, electrical harness <NUM> is electrically coupled to engine <NUM>. Engine <NUM> is an MGU.

At a second opposing end, engine <NUM> is electrically coupled to battery system <NUM> and controller <NUM> via electrical harness <NUM> that extends through vertical shaft <NUM>, such that, in use, electrical harness <NUM> transfers energy from the battery system <NUM> to engine <NUM> which drives propeller drive shaft <NUM> via gearbox <NUM> to rotate propeller <NUM>. The engine <NUM> acts as a generator, deploying energy from the battery system <NUM> to drive gearbox <NUM>.

Electrical harness <NUM> is a flexible electrical connection, rather than a conventional mechanical linkage. The presence of a flexible electrical harness <NUM> extending vertically through foil <NUM>, rather than a mechanical linkage, allows for more streamlined containment of the connection within the foil, thus permitting an improved foil profile with increased hydrodynamic efficiency.

Fluid inlets <NUM> are provided radially around body <NUM> such that channel <NUM> is in fluid communication with the exterior of foil <NUM> i.e. exterior water may flow through fluid inlets <NUM> into channel <NUM>. Thus, when vessel <NUM> is travelling through the water, water flows through fluid inlets <NUM> into channel <NUM> and flows past engine <NUM> and gearbox <NUM> in a direction towards the second end <NUM> of channel <NUM>. Further, water will be drawn in through open first end <NUM> of channel <NUM> and also flow past engine <NUM> and gearbox <NUM> towards second end <NUM>. The flow of exterior water into channel <NUM> and around engine <NUM> and gearbox <NUM> serves to cool the engine and gearbox during use, preventing overheating and allowing operation of the engine and gearbox at higher speeds than possible in the absence of a cooling system. In the figures, fluid inlets <NUM> are shown as slots or gills However, it is to be appreciated that any suitable shape of fluid inlet known to the skilled person and suitable for the circulation of water from the exterior of foil <NUM> into channel <NUM> and around engine <NUM> and gearbox <NUM> may be used in addition to, or as an alternative to, the slots or gills shown in <FIG> and <FIG>. Further, the number and location of fluid inlets <NUM> may be varied from that shown in the figures provided a sufficient volume of fluid flow past engine <NUM> and gearbox <NUM> is possible to provide the required cooling to be achieved during travel of vessel <NUM>.

According to the invention as shown in <FIG>, foil <NUM> comprises a housing <NUM> defining a receiving space in which engine <NUM> and gearbox <NUM> are received. Housing <NUM> provides a watertight housing for engine <NUM>. Engine <NUM> and gearbox <NUM> are located adjacent one another within housing 60housing <NUM> and are connected via shaft <NUM> that transmits the torque and rotation from engine <NUM> to the gearbox <NUM>. The outer surfaces of both engine <NUM> and gearbox <NUM> are located adjacent the interior surface of housing <NUM> such that heat generated during use is absorbed from engine <NUM> and gearbox <NUM> by housing <NUM> and subsequently dissipated into the surrounding water, thus providing an efficient cooling system that avoids the need for mechanical or forced flow of fluid past the engine <NUM> and/or gearbox <NUM> within housing <NUM>.

Propeller <NUM> is connected to gearbox <NUM> distal to engine <NUM> and is engaged with gearbox <NUM> via propeller shaft <NUM>. Propeller <NUM> connects to propeller shaft <NUM> by means of a conical arrangement with a key <NUM> in a conventional manner. Propeller shaft <NUM> enters the gearbox <NUM> through bearings and connects with the gearbox toothed wheels (not shown).

Propeller shaft <NUM> enters housing <NUM> through seals that maintain the water-tight integrity of housing <NUM>.

At the opposing side of housing <NUM>, housing <NUM> connects to foil <NUM> at interface <NUM>. Housing <NUM> is bolted to a flange on the foil (not shown). Interface <NUM> is sealed and channels are provided for the electrical harnesses <NUM> of power train assembly <NUM> to exit the housing <NUM> and extend vertically along vertical shaft <NUM> of foil <NUM>, to provide an electrical connection between the engine <NUM> and gearbox <NUM> and the controller located in the hull <NUM> of vessel <NUM>.

Seals are provided at the point of exit of the electrical harnesses <NUM> from housing <NUM> to maintain the water-tight integrity of the housing <NUM>.

According to the invention as shown in <FIG>, gearbox <NUM> is an epicyclic gearbox and engine <NUM> is a motor generator unit (MGU). However, it is to be appreciated that this is just one embodiment and a skilled person may use an alternative engine to achieve the same arrangement within gearbox housing <NUM>.

In the boat including a hydrofoil system of the present invention, the vessel <NUM> is further provided with a plurality of sensors (not shown) in electrical communication with controller <NUM>, each sensor configured to monitor one or more flight parameters of vessel <NUM> and generate measured flight parameter data based on the monitored flight parameter. This measured flight parameter data is then provided to controller <NUM> which uses the measured flight parameter data to determine what adjustments are required to the engine and adjustment members <NUM> to optimise the vessel <NUM> travel through the water. Adjustment member <NUM> is shown in <FIG> with its hydrodynamic fairing. Controller <NUM> then communicates engine <NUM> to control the operation of propeller <NUM>. Controller <NUM> also communicates with actuators <NUM> to control the position of the adjustment members <NUM> in dependence upon the measured flight parameter data. This has the effect of influencing the speed of the vessel through the water and/or the position of vessel <NUM> within the water i.e. the heave, pitch, roll and/or thrust of vessel <NUM> within the water.

The sensors may provide measured flight parameter data to the controller on a continuous basis or on demand from the controller or in a predetermined programmed manner. Obviously, continuously provided data will produce continuous feedback from controller <NUM> to influence the operation of the engine and the position of the vessel <NUM> within the water, providing continuously optimised travel of the vessel <NUM> through the water.

The sensors may be located in multiple positions embedded in the hull and foils, and measure various flight parameters of vessel <NUM> including, but not limited to monitoring/measuring acceleration, position (pitch, heave, yaw, roll), ride-height data, actuator positional data, and any other useful parameter relating to the movement of the vessel through the water.

<FIG> shows the arrangement where the housing <NUM> is mounted on foil <NUM>, whilst <FIG> show variations on how this can be achieved.

<FIG> shows an arrangement wherein housing <NUM> is provided as part of the gearbox <NUM>, and during assembly, engine <NUM> is slotted into gearbox housing <NUM>, and housing <NUM> subsequently made water-tight in a conventional manner.

In <FIG>, housing <NUM> is provided as part of the engine <NUM> and, during assembly, gearbox <NUM> is slotted into engine housing <NUM>, and housing <NUM> subsequently made water-tight in a convention manner.

<FIG> shows an arrangement wherein housing <NUM> is distinct from both engine <NUM> and gearbox <NUM>. Engine <NUM> and gearbox <NUM> are slotted into housing <NUM> towards one another from opposing ends of housing <NUM>. Alternatively, engine <NUM> and gearbox <NUM> may be sequentially slotted into housing <NUM> from the same end. Housing <NUM> is subsequently made water-tight in a conventional manner to contain both engine <NUM> and gearbox <NUM> therewithin. <FIG> shows an arrangement where housing <NUM> is provided by a portion of foil <NUM>. Engine <NUM> is slotted into housing <NUM>, followed by gearbox <NUM> before housing <NUM> is made water-tight in a convention manner to retain both engine <NUM> and gearbox <NUM> within foil <NUM>.

Alternatively, housing <NUM> may be provided as a channel through foil <NUM>. Engine <NUM> and gearbox <NUM> are slotted into housing <NUM> towards one another from opposing ends of housing <NUM>. Housing <NUM> is subsequently made water-tight in a conventional manner to contain both engine <NUM> and gearbox <NUM> within foil <NUM>.

Finally, <FIG> shows an arrangement wherein housing <NUM> is spatially separated from foil <NUM>. It is to be appreciated that the assembly of housing arrangement may be as described for <FIG>.

<FIG> shows a vessel <NUM> with two foils <NUM>, one of which is hydrofoil system in accordance with the present invention and the other is a foil without the propulsion system of the present invention. It is to be appreciated that a vessel will comprise a minimum of two foils (one towards the front and one towards the rear of the vessel), one or both of which may include the propulsion features of the present invention. Where multiple foils <NUM> are provided, the actuators <NUM> for each flap <NUM> of each foil <NUM> are independently controlled by a single controller <NUM>.

A vessel could be equipped with one hydrofoil system in accordance with the present invention and one non-propulsion foil unit. However, if the weight of the vessel requires more thrust to move around then the vessel could be equipped with two foils provided with propulsion.

The boat including a hydrofoil system of the present invention therefore allows human-free flight control. As each foil <NUM> is always tuned and set for optimum performance i.e. low drag, significantly reduced drag through the water is ensured. This provides the technical advantage of either a greater autonomy range or an increase cruise speed for a given battery capacity.

The engine cooling used by the boat including a hydrofoil system of the present invention, whether water-flow cooling or according to the invention heat-transfer cooling, negates the requirement for a separate mechanical cooling system, thereby reducing the complexity and weight of the system, which contributes to efficiency and increasing battery life.

It is to be appreciated that the boat including a hydrofoil system of the present invention may be an integral part of a newly built vessel <NUM> or may be retrofitted to existing vessels <NUM> to achieve optimal performance.

Claim 1:
A boat (<NUM>) including a hydrofoil system, wherein the hydrofoil system comprises
- a controller (<NUM>);
- a hydrofoil (<NUM>) for engagement with the boat, the hydrofoil comprising a plurality of adjustment members (<NUM>) operable to vary the lift characteristics of the boat;
- a propeller (<NUM>) mounted on the hydrofoil; and characterized by
- a gearbox system, the gearbox system comprising:
a housing (<NUM>) having an interior surface defining an interior space of defined dimension;
a gearing system located within the interior space of the housing and comprising a propeller shaft engagement portion and a gearbox (<NUM>) in mechanical communication with the propeller shaft engagement portion; and
an engine (<NUM>) located within the interior space of the housing and in mechanical communication with the gearbox;
wherein the housing is water-tight, wherein the gearbox and engine are in thermal contact with the interior surface of the housing; and
wherein the gearbox (<NUM>) is an epicyclic gearbox; and
wherein at least a portion of the housing is integral with the hydrofoil, or the housing is mounted on the hydrofoil; and
wherein the propeller is mechanically engaged with the propeller shaft engagement portion and the gearbox system is in mechanical communication with the propeller.