Patent Publication Number: US-2022212756-A1

Title: Retractable hydrofoil on vessel

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/830,981, filed Apr. 8, 2019, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     A hydrofoil ship is a ship that has lift generating wings, foils, or hydrofoils, under the water&#39;s surface. As the ship moves, the foils create hydrodynamic lift from the motion of the water over their surface. The amount of lift generated is proportional to the plan area of the foils, the profile of the foils, the angle of attack of the foils, and the square of the average fluid velocity over the foils. 
     As the speed of the ship in the water increases, the foils generate an increasing amount of lift, until eventually the lift force exceeds the weight of the craft. At a certain point, enough lift can be generated such that the lift force is greater or equal to that of the weight of the ship. At this point, the craft will accelerate vertically, lifting the entire hull of the ship out of the water. This state is called being foilborne. The speed at which this takes place is called the take-off speed. A foilborne ship is advantageous because the ship will no longer experience resistance and friction experience on the hull when the hull itself is buoyant on water. 
     On the other hand, as the ship continues to increase its speed, the lift created by the foils also increases as a function of the square of the ship&#39;s velocity. If this lift force is in excess of the weight of the craft, a vertical acceleration will occur. If the lift force continues to be greater than the weight of the ship, the ship will keep rising higher out of the water until the foils have breached the surface of the water. This is called foil ventilation. At this point, the lift force will collapse, and the ship can uncontrollably descend back to the water&#39;s surface. The maximum speed that the craft can travel at before the foils begin to ventilate due to breeching the water&#39;s surface is called the cruise speed. 
     Currently, vessels equipped with hydrofoils have a static hydrofoil assembly. The hydrofoil assembly include hydrofoils that are fixed onto the ship such that the distance from the hydrofoil to the position of any point of the hull is always constant. With a static foil assembly, there is little to no difference between the takeoff speed, the speed (depending on the configuration of the hydrofoil) to bring enough lift the vessel foilborne, and the cruise speed. Because of the fixed positioning and configuration of the foil, the foil will always have a constant plan area, profile, shape, and angle of attack to the water line. 
     This means that the only variable that will affect the amount of lift generated will be the vessel&#39;s speed. In these cases of current vessels with hydrofoils, there can only be one point, or one speed, where the lift generated is equal to the weight of the vessel. 
     At any slower speeds, the vessel either cannot be foilborne or will descend from being foilborne, which defeats the primary purpose of a hydrofoil. At any higher speeds, the vessel, while foilborne, will continue to rise vertically until the vessel reaches a state of foil ventilation. 
     Thus, current vessels that utilize hydrofoils neither considers the difference between cruise speed and takeoff speed nor achieve having both a takeoff speed and a different, primarily faster, cruise speed. 
     BRIEF SUMMARY 
     The present disclosure relates generally to systems and methods for a vessel. 
     In one aspect, a method, system, or device can include a vessel comprising a retractable hydrofoil. The vessel can include a hull and one or more hydrofoil assemblies connected to the hull. Each hydrofoil assembly can further include a support structure and a hydrofoil operably connected to the hull via the support structure. Each of the hydrofoil assemblies can be configured to retract or extend from the hull such that the hydrofoil of each of the hydrofoil assemblies can move away or move close to the hull. During operation, one or more of the hydrofoils are submerged beneath a water line. Alternatively, during a cruising speed of the vessel, one or more of the hydrofoils can be retracted from being submerged beneath the water line. 
     In one aspect, the support structure of each of the one or more hydrofoil assemblies can include of a pair of elongated booms. In one aspect, the hydrofoil can further include a leading edge, a trailing edge, and side portions on opposite ends of the hydrofoil such that the pair of elongated booms can be operably connected to the opposite ends of the side portions of the hydrofoil. In one aspect, at least a first hydrofoil can be submerged beneath a water line when the water vessel is operational at a given speed. In one aspect, at least a second hydrofoil can be retracted to a position close to that of the hull such that when the ship is operational at a cruising speed, the at least second hydrofoil can be above the water line and the at least first hydrofoil can be submerged beneath the water line. In one aspect, the positioning of each hydrofoil of the one or more hydrofoil assemblies can be configured to reduce a submerged plan area and maximize a lift to drag ratio of the at least the first hydrofoil when operational. In one aspect, each hydrofoil of the one or more hydrofoil assembles can be configured to optimize a stability, balance, and trip of the water vessel. In one aspect, the positioning of each hydrofoil of the one or more hydrofoil assemblies can be based on at least a velocity of the water vessel, a lift caused by the one or more hydrofoil assemblies during operation of the water vessel, a turbulence experienced by the water vessel during operation of the water vessel, or a combination thereof. 
     In one aspect, a ship can include a hull, and a plurality of hydrofoils operably connected to the ship, each of the plurality of hydrofoils having a plan area, the hydrofoils configured to extend or retract to a distance relative to the position of the hull such that at least a first hydrofoil of the plurality of hydrofoils can be submerged under water when the ship is operational at a given speed. 
     In one aspect, the plurality of hydrofoils can be operably connected the hull, connected to a structure supported by the hull, or a combination thereof. In one example, at least a second hydrofoil of the plurality of hydrofoils can be retracted to a position close to that of the hull such that when the ship is operational at a cruising speed, the second hydrofoil can be above a water line. In one aspect, the positioning of each hydrofoil of the plurality of hydrofoils can be configured to reduce a submerged plan area and maximize a lift to drag ratio of one or more of the plurality of hydrofoils when operational. 
     In one aspect, a hydrofoil system can include a foil having a leading edge, a trailing edge, and two side portions, and can include a first support structure operably connected to one side of the two side portions of the foil, and a second support structure operably connected to another side of the two side portions of the foil such that the first support structure and second support structure are operably connected to a vessel. 
     In one aspect, the width of the beam can be substantially equal to the span of the foil. In one aspect, the first and second support structures can be connected to the vessel at each of opposite sides of the vessel. In one aspect, the foil, along with the first support structure and second support structure can operably extend and retract vertically relative to the position of the vessel along an axis substantially perpendicular to that of the axis of a water line. 
     In one aspect, a hydrofoil can include a thin, u-shaped, structure including a base portion that can be substantially flat along a first horizontal axis, and two side portions operably connected to opposing edges of the base portion, each of the two side portions having elongated and substantially flat surfaces suspended perpendicular to the opposing edges of the base portion. 
     In one aspect, the base portion can include two surfaces that are curved along a second horizontal axis. In one aspect, each of the two side portions are operably connected to a vessel. And in one aspect, the two side portions can be configured to extend or retract from the vessel such that the base portion can move away or move close to a bottom surface of the vessel. 
     Other embodiments are directed to systems and computer readable media associated with methods described herein. 
     A better understanding of the nature and advantages of embodiments of the present invention may be gained with reference to the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments are described with reference to the following figures. 
         FIG. 1A  shows a diagram illustrating one embodiment of a vessel according to some embodiments of the invention. 
         FIG. 1B  shows an additional diagram illustrating an alternative view of the embodiment of the vessel according to  FIG. 1A . 
         FIG. 1C  shows a diagram illustrating another embodiment of a vessel according to some embodiments of the invention. 
         FIG. 1D  shows an additional diagram illustrating an alternative view of the embodiment of the vessel according to  FIG. 1C . 
         FIG. 1E  shows a diagram illustrating another embodiment of a vessel according to some embodiments of the invention. 
         FIG. 1F  shows an additional diagram illustrating an alternative view of the embodiment of the vessel according to  FIG. 1E . 
         FIG. 1G  shows a diagram illustrating another embodiment of a vessel according to some embodiments of the invention. 
         FIG. 1H  shows an additional diagram illustrating an alternative view of the embodiment of the vessel according to  FIG. 1G . 
         FIG. 1I  shows a diagram illustrating another embodiment of a vessel according to some embodiments of the invention. 
         FIG. 1J  shows an additional diagram illustrating an alternative view of the embodiment of the vessel according to  FIG. 1I . 
     
    
    
     DETAILED DESCRIPTION 
     I. Introduction 
     According to certain embodiments, methods and systems disclosed herein relate to a vessel and the operation of a vessel. 
     The challenge of designing a hydrofoil craft is to do so such that it has a low takeoff speed, and a high cruise speed. A low takeoff speed is desirable as it reduces the total power requirement of the engines that are needed to get to the low drag state this is being foilborne. A high cruise speed is desirable as it allows for faster transit between origin and destination. As discussed earlier, because current vessels utilizing hydrofoils have a static hydrofoil assembly, lift generated is only a function of speed. The amount of lift generated onto a vessel can only be achieved by a singular speed. Any higher speed and the lift will continue exceed the weight of the ship even when the vessel is already foilborne and any lower speed will cause the vessel to drop back into the water. Thus, the takeoff speed and the cruising speed are the same and can only be one speed. 
     This configuration is not optimal, especially for commercial vessels travelling long distances through water. As discussed earlier, once the commercial vessels, equipped with hydrofoils, becomes foilborne, the speed at which the commercial vessel became foilborne is also essentially the maximum speed of the ship. 
     Attempts have been made to create a speed envelope between takeoff and cruise speed by changing the lift experienced by the vessel unrelated to that of speed. However, current attempts come with significant drawbacks. 
     Existing methods to increase the envelope of speeds between takeoff speed and cruise speed include varying one of the three parameters of the foil that are not related to speed; plan area, profile of the foil or wing, and angle of attack. Plan area can be reduced by having a foil design that reduces the plan area as speed increases, including incorporating a dihedral angle in the foil, and having the tips of the foil penetrate the water&#39;s surface as speed increases. These designs however have considerable drawbacks such as susceptibility to ventilation. The angle of attack can be modified by directly modifying the angle of attack of the foil directly, or by altering the pitch of the entire craft, or both. The profile of the foils can be altered using the addition of flaps (similar to that of ailerons of airplanes) and other lift modifiers that can vary the wings co-efficient of lift. Since lift is proportional to the square of velocity, any increase of speed results in a considerable increase in lift. Subsequently, in order to provide a functional speed range such that lift can be varied independent of speed, a large and complicated mechanical modification to the foils is required. 
     Further, even if the existing methods of changing plan area by increasing or decreasing the plan area of the submerged foil, changing the profile of the foil, and/or changing the angle of attack by modifying the orientation of the foil, the lift to drag ratio is not optimized. An important consideration when designing a hydrofoil is the minimization of drag, as it is the primary driver of fuel consumption. The amount of drag that the foil produces is very similar to the amount of lift that the foil creates, and is proportional to the plan area, foil profile, angle of attack and average fluid velocity. The relationship between lift, drag, and angle of attack varies in such a way that the lift to drag ratio is maximized at specific angles of attack. It is desirable to operate the foils at or close to this optimum angle of attack to facilitate the maximum lift to drag ratio. 
     Further, current hydrofoil vessel&#39;s having fixed hydrofoils will experience even worse drag than vessels that do not utilize hydrofoils at low speeds. At low speeds, takeoff is not possible, so that the vessels including a fixed position hydrofoil would only add to the cross sectional drag to the vessel as compared to the same vessel without the hydrofoil. 
     The following specification describes a vessel configured to operate over a large range of speeds while maintaining an optimized lift to drag ratio. 
     II. Exemplary Hydrofoil Vessel 
     In this specification, reference is made in detail to specific embodiments of the invention. Some of the embodiments or their aspects are illustrated in the figures. For clarity in explanation, the system has been described with reference to specific embodiments, however it should be understood that the system is not limited to the described embodiments. On the contrary, the system covers alternatives, modifications, and equivalents as may be included within its scope as defined by any patent claims. The following embodiments of the system are set forth without any loss of generality to, and without imposing limitations on, the claimed method. In the following description, specific details are set forth in order to provide a thorough understanding of the present method. The present method may be practiced without some or all of these specific details. In addition, well known features may not have been described in detail to avoid unnecessarily obscuring the system. 
     In addition, it should be understood that steps of the exemplary system and method set forth in this exemplary patent can be performed in different orders than the order presented in this specification. Furthermore, some steps of the exemplary system and method may be performed in parallel rather than being performed sequentially. 
     The following specification describes a system including a vessel travelling on water configured to reach a wide range of operational speeds while maintaining an optimized lift to drag ratio. 
     A. Vessel with Hydrofoil Assembly 
     In one example, a vessel with a hydrofoil assembly is provided such that the hydrofoil assembly allows an optimum lift to drag ratio over a wide range of operational speeds. Specifically, the vessel is configured to operate a wide range of foilborne speeds while achieving an optimal lift to drag ratio. In this example, a vessel, or ship is equipped with a hydrofoil assembly that, when operated at certain speeds, can create lift to the vessel and bring the vessel foilborne. Once the vessel is foilborne, the amount of resistance and drag exerted onto the vessel is greatly reduced and the vessel can travel across water more efficiently. 
     In one example, the vessel can propel in the water by utilizing motors with propellers. The motor can be mounted, for example, on the vessel such that the propellers on the motors are submerged beneath the water line whether the vessel is foilborne or not foilborne. In another example, gas turbines can generate thrust and move the vessel with or without being foilborne. In another example, a gas turbine or internal combustion engine generates electric power to electric motors with propellers. The electric motors can be submerged under the water line when the vessel is operational. In another example, a water jet having a jet nozzle operably connected to the vessel can propel the vessel. In another example, the hydrofoil assembly includes a motor system, for example, powered by an internal combustion engine, with propellers either operably connected to or part of the hydrofoil assembly. 
     Further in this example, the hydrofoil assembly is also extendable and retractable such that lift can be varied depending on the speed. In this case, the hydrofoil assembly can be configured to maximize lift to achieve a low takeoff speed. The hydrofoil assembly can also be configured to produce the exact amount of lift required, as to maximize the moving speed, or cruising speed. Further, the hydrofoil assembly can also be configured to optimize stability, balance, and trip of the vessel. 
     In this example, the maximum speed is accomplished by removing portions of the hydrofoil assembly itself from being submerged under water so that a higher speed can be reached and still achieve the same amount of lift, with the remaining submerged foils operating at close to or at their optimum lift to drag ratio. 
     In one example, a hydrofoil ship has one or more retractable and extendable hydrofoils. The total amount of lift can be decreased with the increase of speed by physically retracting one or more of the of foils out of the water as the craft increases its speed. This will cause the plan area to decrease by amount equal to the plan area of each of the hydrofoils retracted from the water (for example, decrease by 50% if two retractable hydrofoils of a total of four equally sized hydrofoils are retracted from being submerged underwater. The foils that remain in the water can remain at or close to their optimum angle of attack to minimize drag. Once retracted, the foils will be secured to the hull in a manner that minimizes air drag. In one example, the retractable and extendable hydrofoils can be retracted and extended via a mechanical system connected to the hydrofoil ship. In one example, the mechanical system can be a hydraulic system, including a hydraulic system using hydraulic actuators. In another example, the mechanical system can be a system that includes motors and gears. 
       FIG. 1A  illustrates an exemplary floating body or ship with retractable hydrofoils in accordance to one example of the invention.  FIG. 1B  illustrates the same exemplary ship of  FIG. 1A  in a different view. As illustrated in  FIGS. 1A-1B , an example floating device  10 , or a ship is provided. In this example, the floating device  10  includes a vessel  100  having a hull  110  is resting on a water line  115  where a portion of the vessel  100 , including the hull  110 , is submerged beneath the water line such that the vessel  100  is floating on water. The vessel  100  also includes a hydrofoil assembly  120  operably connected to the vessel either at the hull  110  or a structure attached to the hull  110 . In one example, the vessel  100  is a commercial vessel containing a plurality of shipping containers  102 . The vessel  100  illustrated in  FIG. 1A-1B  is illustrative only. The vessel can be that of any kind of ship such as a commercial ship, commercial vessel, freight ship, military ship, race boat, surfboard, monohulled ships, catamarans, etc. As illustrated in the side view of  FIG. 1A , the vessel  100  includes four hydrofoil assembly  120 &#39;s. In another example, there can be any number of hydrofoil assembly  120 &#39;s on the vessel  100  depending on the size, shape, etc. of the vessel  100 . In this example, the each of the four hydrofoil assembly  120  are spaced evenly across the centerline of the vessel  100 . This configuration allows for an even distribution of lift exerted onto the mass of the hull causing an even lift when the vessel  100  is operational. 
     In one example, the vessel  100  as illustrated in  FIG. 1A-1B  is in a resting position. Each of the hydrofoil assembly  120  are fully retracted and each of the hydrofoil assembly  120  is barely submerged underwater. In another example, the vessel  100  is operation such that a propeller connected to an engine or any kind of kinetic movement device is causing the vessel to move across the water. In this example, the vessel  100  can be operating at a speed slow enough that foiling does not need to occur and therefore, the hydrofoil assembly  120  is in a fully retracted configuration. 
     In one example as illustrated in  FIGS. 1A-1B , each of the hydrofoil assembly  120  includes a hydrofoil  122  and a hydrofoil support  124 . The hydrofoil  122  of the hydrofoil assembly  120  can cause lift when the vessel  100  is operational and water flows over the surface of the hydrofoil  122 . The hydrofoil support  124  connects the hydrofoil  122  to the vessel  100  either at the hull  110  or another structure operably connected to the vessel  100 . 
     1. Foil 
     In one example, the hydrofoil can include a leading edge or nose, a trailing edge with the profile or shape of a typical wing of an aero plane. In this example configuration, a top surface of the foil is curved, and the bottom surface of the foil is also curved such that when fluid flows above and beneath the foil, a pressure imbalance from the movement of the foil causes a net lift to the foil. This particular configuration should be construed as illustrative only. In another example, at least one of the surfaces of the foil can be flat, or concave. For example, like that of a typical aero plane wing, one surface, e. g. a bottom surface of the aero plane wing will be flat or substantially flat, and one surface, e. g. a top surface of the aero plane wing will be curved in a concave shape. Other foil shapes, from a cross-sectional view, can include but not limited to straight shapes, tapered shapes, concave shapes, crescent shapes, etc. 
     In one example, the foil can pivot about an axis such that the angle of attack of the foil can be changed where in some instances, movement of the foil through water will cause no lift depending on a certain configuration of the foil and movement of the foil through water will cause lift depending on another configuration of the foil and so forth. 
     In one example, the hydrofoil  122  can include a winglet or ailerons or flaps at the trailing edge of the hydrofoil  122 . The flaps can change the overall profile of the foil as well as the angle of attack on the water and therefore changing lift. 
     2. Foil and Support Structure 
     In one example, the hydrofoils  122  are operably connected to the vessel  100 , either at the hull  110  of the vessel  100  or a different portion of the vessel by one or more structures. The hydrofoil  122  is connected to the hull  110  by a hydrofoil support  124 . In one example, the hydrofoil support  124  can include a pair of support structure. The pair of support structures can be two elongated booms or struts that are substantially straight disposed at opposite ends of the hydrofoil  122  configured vertically and connected to the hull. The two elongated booms of the hydrofoil support  124  can move up and down as to extend and retract from the vessel. 
     In one example, the support structures extend from each of two side portions of the hull beneath the vessel and connects to a single foil structure at each of two side portions of the foil. In another example (not shown), a single support structure can extend along a centerline of the hull, center portion relative to the beam or center portion from a front-view of the vessel and extend beneath the hull and connect the foil at a center portion of the foil, also from a front view. 
     In one example, the support structures are also thin like that of the hydrofoil  122 . In one example, the hydrofoil assembly  120  is a u-shaped structure including a base portion that is substantially flat along a first horizontal axis. In this example, the first horizontal axis can be the axis parallel to that of a beam of the vessel  100 . The u-shaped structure can also include two side portions operably connected to opposing edges of the base portion, each of the two side portions having elongated and substantially flat surfaces similar to that of the base portion. The two side portions are suspended perpendicular to the opposing edges of the base portion, thus creating a u-shape. In one example, the base portion is curved along a second horizontal axis, such that the curvature creates lift when the base portion flows through water at a certain angle of attack. The second horizontal axis can be the axis parallel to that of the centerline axis of the vessel  100 . The u-shaped structure is configured to be operably connected to the vessel such that the base acts as a hydrofoil and the entire u-shaped structure can be variably suspended vertically beneath the hull of the ship and retracted vertically to the hull of the ship. 
     In one example, the span of the hydrofoil  122  is substantially the same as the width of the beam of the vessel  100 . 
     In another example, not all of the hydrofoils  122  necessarily need to be of the same shape, profile, orientation, or size. Multiple foiling mechanisms can be configured such that some of the hydrofoil assemblies  120  are used for foiling and creating the substantive amount of lift and some of the hydrofoil assemblies  120  are configured for stabilizing the vessel  100  when foilborne. 
     B. Operation 
     As illustrated in  FIGS. 1C-1D , the vessel  100  includes a plurality of retractable and extendable hydrofoil assemblies  120 . When extended, the hydrofoil  122  of each of the hydrofoil assemblies  120  are submerged beneath the water line and are a certain distance from a bottom surface of the hull  110  of the vessel  100 . In this extended configuration, where each of the plurality of hydrofoil assemblies are extended, each of the hydrofoil  122  can cause lift to the vessel  100  when the vessel  100  is operational. As discussed earlier, at some point the speed will create enough lift such that vessel will be foilborne, known as the takeoff speed. Once the vessel  100  is foilborne, going in the direction of travel  200 , the water drag experienced by the vessel  100  is only due to portions of the hydrofoil assembly  120 &#39;s including all of the hydrofoils  122  and portions of the hydrofoil supports  124 . 
     In the example illustrated by  FIGS. 1C-1D , there are four hydrofoil assemblies  120  and each of the hydrofoil assemblies  120  are extended and the hydrofoils  122  are fully submerged into the water. In one example, the lowest takeoff speed necessary to create lift and cause the vessel  100  to be foilborne is achieved with all four hydrofoil assemblies  120  fully submerged. 
     C. Operation at High Speeds 
     Once the vessel  100  is fully foilborne in the configuration of the hydrofoil assemblies  120  illustrated in  FIGS. 1C-1D , any increase in speed will cause more lift which will eventually cause a problem once the lift raises the vessel  100  so much that the hydrofoil  122  reaches the water line  115 . 
     In one example, as illustrated in  FIGS. 1E-1F , once the vessel  100  is foilborne, the vessel  100  can operate at a higher speed with a reduced plan area of the hydrofoil, such that the lift stays the same (the lift being the same as the weight of the vessel) as that of the example configuration in  FIGS. 1C-1D . As illustrated in  FIGS. 1E-1F , the two center retracted hydrofoil assemblies  120  will cause at least the plan area of the total plan area of the hydrofoils  122  to decrease (for example by 50% because two of the four totally submerged hydrofoils  122  have been retracted fully from the water). However, to maintain the same amount of lift, the vessel  100  can increase its speed at the direction of travel  300  such that the lift generated by the two outer submerged hydrofoil assemblies  120  will increase, and the total lift experienced by the vessel will continue to remain the same as when the vessel  100  was first foilborne, equal to the weight of the vessel. The result will be that a new faster speed will be experienced by the vessel  100  in the same foilborne state. The speed is the new cruising speed. 
     Additionally, the lift to drag ratio in the configuration illustrated in  FIGS. 1E-1F , where one or more hydrofoil assemblies  120  are fully submerged and one or more hydrofoil assemblies  120  are fully retracted, are optimized. In this example, instead of changing the angle of attack or profile of each of the submerged hydrofoils  122 , 50% of the submerged hydrofoil assemblies  120  are removed. Thus, substantially 50% of the water drag experienced by the totality of the submerged hydrofoil assemblies  120  is also removed, thereby optimizing lift to drag ratio and optimizing efficiency and power required to move the vessel  100  at the cruising speed. 
     In one example, in order to minimize the sudden impact of an entire ¼ or ½ of the total amount of plan area, that is the number of foils of the total foils removed from the water, the hydrofoils can also be configured to change angle of attack by pivoting about its own axis, change plan area, or change profile with ailerons, or a combination thereof so that the vessel  100  will not experience sudden turbulence when the vessel  100  experience a sudden lack of lift when one or more hydrofoil assemblies  120  are retracted from the water line  115 . 
     Since the retraction of an entire hydrofoil from the water would normally produce an abrupt and significant change in lift, the lift generated by each of the foils on the craft will be able to be modified by configuring a change of angle of attack by pivoting about its own axis, plan area, or profile with ailerons, or a combination thereof. This will facilitate the smooth removal of a foil from the water without having an abrupt impact on the total lift generated. 
     D. Variable Configuration of the Hydrofoil Assembly 
       FIGS. 1G-1J  illustrates substantially the same concepts as that of  FIGS. 1C-1F , respectively with a slight variation. In the examples illustrated in  FIGS. 1G-1J , the hydrofoil supports  124  of the hydrofoil assemblies  120  can extend and retract to any length within the minimum retractable length and maximum extended length. For example, as illustrated in  FIGS. 1G-1H , the four example hydrofoil assemblies  120  are only partially extended as compared to that of previous examples. In this example, the vessel  100  can still achieve lift and become foilborne even without as much vertical climb as that of vessels described in previous examples. In this example, the water may be non-turbulent, or laminar, such that wave profiles are shallow, and a minimal lift can cause the entire vessel to hover above all of the waves of the water that the vessel  100  is currently moving across. This is advantageous because the vessel  100  will experience even less water drag that of a vessel with fully submerged hydrofoil assemblies  120  since at least a portion of the hydrofoil supports  124  will be above the water line  115  as compared to that of hydrofoil assemblies  120  with hydrofoil supports  124  fully extended beneath the water line  115 . 
     As illustrated in  FIGS. 1I-1J , the same concept applies to the transition of the vessel  100  from takeoff speed to cruising speed. In this example, the one or more hydrofoil assemblies  120  that are kept extended experience less drag than that of hydrofoil assemblies  120  fully extended since at least a portion of the hydrofoil supports will be retracted and above the water line as compared to that of hydrofoil assemblies  120  with hydrofoil supports  124  fully extended beneath the water line  115 . The one or more fully retracted hydrofoil assemblies  120  will still be fully retracted and above the water line  115 . 
     In this specification, reference is made in detail to specific embodiments of the invention. Some of the embodiments or their aspects are illustrated in the drawings. 
     For clarity in explanation, the invention has been described with reference to specific embodiments, however it should be understood that the invention is not limited to the described embodiments. The invention covers alternatives, modifications, and equivalents as may be included within its scope as defined by any patent claims. The following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations on, the claimed invention. In the following description, specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be practiced without some or all of these specific details. In addition, well known features may not have been described in detail to avoid unnecessarily obscuring the invention. 
     In addition, it should be understood that steps of the exemplary methods set forth in this exemplary patent can be performed in different orders than the order presented in this specification. Furthermore, some steps of the exemplary methods may be performed in parallel rather than being performed sequentially. The present invention may be practiced with different combinations of the features in each described configuration. 
     The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to comprise the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     While the invention has been particularly shown and described with reference to specific embodiments thereof, it should be understood that changes in the form and details of the disclosed embodiments may be made without departing from the scope of the invention. Although various advantages, aspects, and objects of the present invention have been discussed herein with reference to various embodiments, it will be understood that the scope of the invention should not be limited by reference to such advantages, aspects, and objects. Rather, the scope of the invention should be determined with reference to patent claims.