Patent Application
20240083546
The present disclosure relates to watercraft systems. The present invention more particularly relates to watercraft borne on planing skis.
Watercraft of all types must contend with various hydrodynamic principles. Energy efficiency is often a driving aspect of design, as more efficient watercraft generally consume less fuel. More efficient systems require less powerful propulsion to achieve desired performance metrics, and thus are generally cheaper to build, operate, and/or maintain.
One approach to improving watercraft efficiency is to mount lifting surfaces to the craft, often known as hydrofoils. In principle, when the watercraft is propelled forward, the lift surfaces produce lift, thus raising the watercraft at least partially out of the water, reducing the portion of the body of the craft that is in contact with the water. This generally reduces hydrodynamic drag, enabling the craft to operate at greater efficiencies. Typical drawbacks with the hydrofoil approach relate to design complexity and scenarios wherein the craft is operated at relatively lower velocities or while stationary; without the lift surfaces producing sufficient lift, the craft will settle deeper into the water, exposing the necessary support structure to drag forces. Hydrofoil-based watercraft are often less hydrodynamically efficient than more typical designs when not operating at velocities sufficient to result in enough lift to raise the body of the craft.
Features and advantages of various embodiments of the claimed subject matter will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals designate like parts, and in which:
The systems and methods disclosed herein provide a ski-borne watercraft with improved performance and stability. The floating craft, a watercraft, is designed to minimize weight and enhance performance. Certain items require special attention for weight sensitivity. (Multiple) floating skis, trusses along the one or more skis, the stiff frame created when a truss is connected to the adjacent truss along the horizontal truss member at the top of each truss vertical member via a truss connecting member. Preferably one-third down each vertical member, another tube, or truss connecting member, will be connected to the parallel piece on the adjacent truss. The truss connecting tubes are preferably made of the same material as the top, bottom, and vertical members of the trusses. Further, the one or more bodies set between the trusses may be positioned to rest on the truss connectors, potentially the top one-third of the height of the truss verticals (preferably the trusses pass through the body or are otherwise affixed mechanically thereon/therethrough). Finally, the power system should be lightweight.
As a non-limiting example, a system consistent with the present disclosure may include a body or bodies for housing persons or supplies, a truss structure connected or holding the body or bodies, and one or more floating skis connected to the truss structure. Preferably, the top surfaces of the skis may be connected to the bottom or underside of the truss structure. Forward motion of the system along the surface of a body of water may allow the skis to generate lift. Depending upon velocity, the skis may generate sufficient lift as to enable the skis to plane, or skim, along the surface of the body of water, depending upon speed. Skis may temporarily pitch (bow up/stern down) drawing more initial lift prior to planing, wherein surface tension forces may add to lift.
Example systems may be any of a variety of sizes and thus serve a variety of functions; for example, in some embodiments the watercraft may be as small as a single-passenger vessel with a length overall (LOA) of less than twenty-five feet, preferably around thirty feet. In other embodiments, the watercraft may be a 500+ passenger vessel with a length-overall (LOA) of well over one hundred feet.
In one embodiment, a horizontal truss connector beam passes through the body to attach one vertical truss member to an adjacent vertical truss member. Top (horizontal) truss connectors may be used to support a floor in the body, either at the bottom of the body, or when dividing the body into two levels, supporting the upper level, or other like support. The first four segments may be designed to consider structural load on truss. It is important to note that the ski and truss form an upside-down ‘T’ structure, when securely fastened at numerous places where the truss contacts the ski. Each truss and ski adds to the rigidity, stability, and strength of the other. Cross braces set along a horizontal plane may be used to connect the truss structure at vertical members, preferably within the lower two-thirds of the truss structure, and bind with the vertical struts and thereby bind the other trusses (related with each ski) together. Cross braces may be supplied in an X-form at forty-five-degree angles from bow/stern, intersecting one another at ninety-degree angles.
In one embodiment, power may be provided by diesel engines powering electric generators located in the center of the craft, between the two bodies (for proper weight distribution). Electric power cables may pass inside the af truss and/or vertical strut members through the skis and pod structure to the electric motors powering the water jet pumps. Cooling and fresh air may be furnished to the jet pump pods as per design requirements, either through outlets or slats. A passenger version of the craft (e.g. shown below in
Body 102 may be made of any of a plurality of light materials, as will be understood by those skilled in the art. For example, body 102 may be made of fiberglass, steel, aluminum, etc. Body 102 may have a generally aerodynamic shape with a tapered front end 103, as shown in
In the most preferred embodiments, the total weight of the watercraft, empty or when loaded, will be considered in the calculation of the size (width, length, and height) of the floating skis. It is preferred that the amount of fluid/water displaced by the skis (or more preferably a portion thereof) is of a weight equivalent to the craft. In such a way, at rest, the skis will be partially submerged, while maintaining the top of the skis, the truss structure, and the body above water. In one exemplary embodiment for a small passenger vehicle, the skis may be twenty seven inches wide by thirty-two feet long by one foot high, providing a two hundred sixteen cubic foot (cf) volume. Skis, if fully submerged, may displace approximately 13,824 pounds of fluid (considering a value of 64 lbs/cf for sea water). The vehicle weighing approximately eleven thousand pounds (when fully loaded) may result in an approximate 75%-80% submersion at rest.
Truss structure 122 is generally comprised of a plurality of truss members 124, e.g., 124n, or members, and/or webbing, which are comprised of a relatively lightweight material, such as structural tubular aluminum, tubular steel, fiberglass, resin-based composite material, carbon fiber, etc. In smaller embodiments, the truss structure may be made from a hollow welded thermoplastic, PVC, polypropylene, PP-R, PP-RP (RCT), or structural aluminum or steel tubing or possibly polyvinyl thick-walled water pipe. A fitting or truss other type of piping. Pipes may form the truss and may be thermo-coupled to joints or directly onto skis.
Truss structure 122 may be any of several truss designs, such as, for example, a common pitched truss, a Pratt truss, a lattice truss, a space frame truss, etc. In a preferred embodiment, truss structure 122 may include a common pitched truss including alternating diagonal members, as shown in
A truss support point 281 may be level with the top of the truss where the vertical strut joins the top truss connector (TC), TC as horizontal truss (preferably tube) members may pass through the body to connect with adjacent vertical struts. Horizontal truss connector members 125 may be parallel to the water surface or may be set at an angle other than that of the water surface. Horizontal truss connector members 125 may join adjacent truss members. The truss support point 281 may be preferably located one-third of the way down from the top of the truss to the top of the lower TC attached to the adjacent truss. For example, as shown on
Ski 142 is similarly connected to truss structure 122 at a plurality of joints (not labeled in
F=1.28*βa/V2
The fixed constant, 1.28, represents the turbulence about the free edges of the flat plate.
Where the flat plate is at an angle other than perpendicular to the water stream, the force (F′) acting upon the flat plate may be separated into a lift and a drag component by the following formulae after multiplying the force (F) by the sine of the angle (sin θ), or F′=(sin θ)*F
Power=((Drag)(a)(Velocity))/550=((3.37)(44)a)/550=0.27a H.P.
Where the watercraft has a lower surface area of 192 ft, the power required is:
Power=(0.27)*(192)H.P.=51H.P.
As can be seen, as the angle θ approaches 0, the Power required to lift the vehicle drops. As the angle increases, substantially less power may be required to power the vehicle. Once planing close to 0.1 degrees, the energy required to propel the vehicle substantially drops.
In some embodiments, ski bottom 144 of ski 142 is generally planar. However, in some embodiments, ski bottom 144 may include some degree of curvature, for example near ski tip 143, ski 142 may be angled in order to penetrate small waves. Additionally, in some embodiments, ski bottom 144 may include an applied coating of one or more low-drag materials to further reduce hydrodynamic drag enacted upon ski 142 and to otherwise deter or counteract marine growth inhibiting movement through the water. Ski tip 143 may be generally curved, rounded, or pointed so as to reduce overall wind resistance and assist in wave penetration.
In some embodiments, ski 142 may connect to two truss structures rather than one. For example, rather than a single truss 122, watercraft 100 may include multiple truss structures. This may improve stability, particularly for larger embodiments of watercraft 100.
Ski 142 may be hollow or solid. For example, in some embodiments, ski 142 may include a hollow aluminum section, wherein space inside ski 142 may house components such as fuel, motor 146, or water ballast to improve stability. When liquids, fuel, water, or otherwise, serve as ballast, a pump may be used to move liquid forward/backward within the skis to maintain stability and assist in operation and motion of watercraft 100. In other embodiments, ski 142 may be a solid structure (such as fiberglass). In general, larger embodiments of watercraft 100 may be more likely to benefit from a hollow ski 142, but embodiments wherein smaller (e.g., small passenger) watercraft 100 include hollow skis and embodiments wherein larger watercraft 100 (LOA of one hundred feet or greater, capacity for five hundred or more passengers, etc.) include solid skis are fully considered herein.
Ski 142 may further serve as a mounting point for motor 146. This way, a propeller coupled to an outdrive attached to a motor 146 may remain submerged in water even as watercraft 100 is largely lifted out of the water (by, e.g., lift 1o produced by ski 142 and/or any hydrofoils).
Dimensions of ski 142 and active planing surface may vary with embodiment, but as an illustrative example, a smaller passenger watercraft 600 as shown in
Width of ski 142 preferably may increase as watercraft 100 LOA increases. Wider skis may provide more roll stability and support additional weight of watercraft 100 at the cost of increased drag and thus reduced efficiency.
Body 102 rests on the lower horizontal TC 125, approximately one-third down each truss vertical strut fit between the trusses 122. The top of the truss complex, the TC, goes through middle of body to middle truss. Truss members 124 may include horizontal and vertical struts, as well as diagonal members Preferably all truss members 124 are made of the same material, with a light weight and high tensile strength. A braking plate 808 may be included at the front part of the craft and may provide lift to the front of the ski 142, thus increasing the angle to the water of the whole ski 142, thus further braking the craft by ski 142 (and all skis). The angle created between the water surface and the ski 142 may be acute in degree. Each ski may have a braking plate and in such embodiments, each braking plate may be applied in unison to prevent frame stress.
In some embodiments, watercraft 200 may include a truss structure 222 set above and connecting with skis 242a-c. For example, while some frame structures may support the weight of bodies 202a-b on skis 242a-c by including truss members 124 that are at least partially vertical, other TCs 125 may prevent skis 242a-c from drifting apart from each other via trusses 222 with truss members 124 parallel to the plane of the body of water over which watercraft 200 travels. In some embodiments, ski connecting TCs 125 may be planar but not parallel to the plane of the water. Instead, some truss structures 222 may be at an angle (e.g., an angle of 45°, 15° or greater, 50 or greater, etc.) with respect to the plane of the water. The truss 222 may be centered above the center of the ski 242a-c.
Truss structure 222 may generally include at least one vertical support strut, or vertical support member, extending vertically from a top of the lower truss tube. This support member may be centered with respect to port and starboard of the ski 242.
It is contemplated that when actively moving/planing, the truss connection in the center of the truss and ski cannot be relied upon to prevent rocking/rolling of ski on bottom of truss. Strap 224 is set at approximately ninety degrees to truss bottom (e.g. relative to water level, ski top surface). Steel strap 224 is preferably one quarter-inch by three-inches with the lower portion attached to the ski upper side, preferably at outer edge of ski. Steel strap 224 stabilizes the ski 242 against rolling/twisting as the truss attachments in the center of the ski 242 (to the bottom of the truss) cannot be relied on to prevent rolling torsion forces. Straps 224 may relieve torsional stress when attached to a point at which a vertical truss support member 124 attaches to the ski 242. It is contemplated that, when actively moving, planing will be conducted at less than one degree from horizontal.
In larger embodiments as those shown in
The motor and pump may be located in a changeable/removable motor pod 942 attached to the rear end 902 of the ski 900. Motor 946 may be fitted to the ski 900, or otherwise power can be provided from engine 205 in generating room 205a to power shaft 948. Water flows through inlet 953 at bottom of ski 900, through impeller (not shown, driven by shaft 948 rotation) and out a water jet ski outlet 960. Pod 942 may be slid into rear of ski 900 along ski track 980 and motor pod track 981. Tracks 980 and 981 on ski 900 and motor pod 942, respectively, may create a complementary slide track to allow motor pod 942 to be installed. Plates may secure motor pod 942 in place once installed. When access is required to motor 946 in motor pod 942 when motor pod 942 is installed and vehicle is waterborne, coinciding ports may be set within ski recess 904. This allows one to exit from ski 900 down into motor pod 942 to access motor 946 for maintenance, removal/installation, etc. Servicemen may enter into top of pod, through maintenance portal, either directly, or from within rear portion of ski through a bottom surface of ski over pod. Gaskets 970 and 971 may fit on motor pod 942 and ski 900, respectively, to provide a seal to prevent flooding of motor pod 942 when accessed. Gaskets may include a hollow square or hollow round as known in the art with at least two-foot diameter, or 2′×2′ (if square) space opening therebetween to allow serviceman vertical passage, or more preferably six-foot by eight-foot access portal similar to a small elevator, or larger as in use for a freight elevator to allow drop and lift of equipment into pod and/or ski through portal. Gaskets 970 and 971 may be inflatable to provide the seal and otherwise make a minimal profile so as not to interfere with motor pod 942 installation. Cap 944 may be placed above motor hole 947 to otherwise seal motor pod 942. Upper motor hole (not shown) in ski recess 904 is obscured by gasket 971. Gaskets 970 and 971 may be rectangular, square, or otherwise rounded in shape, so long as they are complementary to allow for sealing. In some embodiments, only one gasket may be needed, and it may be preferably located on the pod. It is contemplated that work may be done on the motor 946, in a shop when it is removed and re-installed via motor hole 947.
Hydraulic actuator 265 is provided for propulsion and steering. Trim tabs 246a and 246c may be provided to assist in planing and may be set on rear of skis 242. Trim tabs 246a,c may alternatively be placed in the air and attached to the watercraft 200 and/or structural frame and/or body 202 to provide aerodynamic spoiling, and help fine tune orientation of watercraft 200.
Ski 242 may be outfitted with brakes 260 that may be deployed on lower side of ski 242. Brakes 260 may rotatably deploy and orient to capture and brake moving vehicle. Ski tip 143 may also include a nose-in prevention, to rectify a scenario where skis 242 achieve a negative angle from horizontal, causing the nose of the watercraft 200 to point downward.
Large passenger craft embodiment, shown in
Small passenger watercraft 600 may additionally include a braking plate (not shown), controllable by an operator of small passenger watercraft 600. The braking plate may be connected to one or more of skis 642 via, for example, one or more hinges. The braking plate may be controlled to extend or fold away from skis 642 into the body of water, resulting in a braking action. This may, for example, enable an operator of small passenger watercraft 600 to quickly reduce speed. A rudder set behind one of the skis 642 may be used to steer the watercraft 600. A rudder may not be needed when the outdrive 648 is capable of pivoting to steer. Outdrive 648 pivot control may be provided to a steering wheel 658 to turn craft. Similarly, braking plate may act as nose pin preventer, and include automated activation when pitch of skis 642 drops and small passenger watercraft 600 points nose down at negative angle relative to water surface.
Water transfer tanks may be employed to balance vehicle, wherein one or more reversible pumps may be employed to move water within body 602 between rear water transfer tank 653 and front water transfer tank 651 to maintain a level vehicle, preferred once planing. Front water transfer tank 651 and rear water transfer tank 653 may be located within the body 602 or within the longitudinal ski 642.
In one embodiment, a bridge 210 or body 202 may rest on a lower truss connecting member 125 set between the middle truss 222b and starboard truss 222c and another bridge 210 or body 202 may rest between the port truss 222a and middle truss 222b to stiffen the structural framework. This truss and connecting framework prevent the planing surfaces of the skis 242 from achieving different planing angles. The strength of this framework may also be enhanced by the use of ‘X’ braces connecting the lower two-thirds of the truss vertical strut 223 to the same place in the adjacent truss, if ‘X’ brace would not tend to buckle from waves or hits from waves.
The large square footage of the planing surface on the bottom of the skis may allow the craft to be less sunken into the water by its loaded weight. The craft planing surface remains closer to the water surface which may allow for easier acceleration from launching to planing. The large planing surface may only push the water down where a normal watercraft or boat may move the water to either side of a center spine along the keel. The present invention may diminish the amount/number of waves created such that no or very small waves are created, which is ideal for river and coastal straightaway navigation. A curved river and coastal area or fog may require reduced speeds. An additional attribute may be the uniquely appropriate application to shallow waters, with a shallow draft or use in beach landings.
The truss structures described herein generally include a plurality of horizontal, vertical, and diagonal struts, or members. The motors may be any of a plurality of commonly available customer-off-the-shelf motors or engines, as will be appreciated by one of ordinary skill in the art. For larger embodiments (e.g., the watercraft of
The body or bodies may comprise any of a plurality of commonly known features, including a deck, surface, etc. In some embodiments, the watercraft may include an elevator, staircase, ladder, or other means to enable one or more passengers to traverse from a ski to an upper surface of the body (e.g., a deck). Vertical members, such as struts, can be used in a truss in which they strengthen the complex. Diagonals in the truss structure may be referred to herein as webbing, and may connect to the truss with two truss connecting members per each truss vertical strut to form a rigid structural frame encompassing the top one-third of the truss bodies to sit between the truss resting on the bottom truss connectors with the top horizontal truss connector running through the middle of the body. Water pumps may pivot laterally to provide steering mechanism and up and down for trim adjustment.
For larger watercraft it may be adequate for water tanks 651 and 653 to be half-full and located in the front and back of each ski with a connecting waterline and two-way transfer pump that would also be used for trim purposes.
