Abstract: A surfboard having at least one fin, which an be removably connected to the underside proximate to the board tail end. First and second graduated channels are disposed in the underside, each having a front end shallower than a tail end, wherein the front ends are proximate to the board midsection and the tail ends are proximate to the board tail end, and wherein the graduated channels are substantially parallel to the central axis of the surfboard. A keel is disposed in the underside along the central axis, centered between the first and second graduated channels.

Abstract: A multi segment articulated Surface Effect Ship. Flexible air seals are formed between hull modules with a gas cushion contained between the side hulls under the entire length of the ship. In one embodiment the cushion formed may act as one continuous gas cushion whereby air cushion pressure generated or flowing from a leading car, or modular segment, flows rearward to supply or augment the cushion pressure necessary to support the following modules at the required operational draft. Hull configurations adaptable to the multi-unit, articulated surface effect ship described in the invention include conventional and air cushion assisted catamaran, trimaran and quadramaran designs and configurations.

Abstract: The invention relates to a ship's bow with a central inclined plane area and starboard and port catamaran-like runners laterally thereto, the inclined plane area and runners in the midships direction pass roughly into a fictional keel line. The aim is to create such a ship's bow which, whilst being very economic when operating the ship can be used in modular manner for the most varied ship types and operating zones. To this end the runners are given a wedge-like construction and at the front runner end is provided a free flow attack opening for the inclined plane area, which is constructed with a specific inclination angle ?.

Abstract: A boat hull providing substantially enhanced stability, safety and comfort over conventional boat hulls in common use, incorporating at least one relatively narrow, more-or-less vertical slot (23) running longitudinally and/or laterally through the hull of the boat and positioned so that the slot(s) (23) intersects a major portion of the depth of the water displaced by the boat hull. The slot(s) (23) may be fully or partially closed at any of its fore-end (31) or aft-end (33) or bottom-edge (25).

Abstract: The present invention comprises systems and methods of utilizing hull arrangements that combine aerodynamic and hydrodynamic effects to provide marine vessels with broader ranges of performance capabilities. The combination hull arrangements variously combine V-hulls, slot aspects, topographic features, and other hull characteristics that enable a vessel to retain the primary performance benefits of conventional V-hulls and achieve assorted improvements. Embodiments of the slot-V hull system employ specifically shaped hull characteristics to influence the manners in which water, air, and air/water spray mixtures interact with the vessel's hull. One principal operative effect can enable a vessel with the slot-V hull system to achieve a planing attitude more rapidly and efficiently than a standard V-hull.

Abstract: A molded boat hull is provided having a channel forming member extending between a motor mounting transom and an aft riser that forms a step in the bottom portion of the boat hull. The channel forming member has at least one open side and at least an opening in another side to provide a fluid flow communication channel from the atmosphere to the underside of the boat in the step area. The channel forming member is formed as an integral part of the boat hull during forming of the boat hull by molding.

Abstract: A hydrofoil craft, particularly a method of economically modifying a conventional hull with cambered foils to obtain and calculate increased lift from dense spray and to achieve enhanced craft performance is disclosed. The present invention improves speed, fuel efficiency and rough water stability, reduced pitch and vertical accelerations. A catamaran or V-bottom hull is modified with chine mounted aerofoils, flexible dihedral cambered foils positioned beneath the water line and on either side of the bow so as to create turbulence in the forward end of a tunnel(s). Tunnels are created on the V-bottom hull by the chine mounted aerofoils. Fixed forward tunnel cambered foil(s) and/or fixed or adjustable center tunnel cambered foils at the stern end of the tunnel to generate lift from pressure caused by dense spray in the tunnel(s) may also be provided. Adjustable cambered stern foils are mounted on the transom end of the tunnels.

Abstract: The invention is directed to a watercraft hull design that comprises a hull having a bow, stern, top, and bottom. A wedge-shaped wave spreading system is located at a forward portion of the craft. The wave-contacting surface planes of the wave spreading system are positioned substantially perpendicular to the plane of smooth water. The bottom edge of the wave spreading system is positioned near the level of smooth water when the watercraft is at cruising speed. The wave spreading system has a forward apex which forms a substantially perpendicular or vertical leading wedge to the plane of water. Since the apex and planes of the wave spreader are substantially perpendicular to the water, oncoming waves encountered by the wave spreader will tend to be deflected horizontally. Accordingly, the watercraft will more easily “cut through” waves instead of riding over them. Located rearwardly of the wave spreader, an internal hull prow is spaced from the wave spreading system, creating an air space therebetween.

Abstract: A flow control mechanism, for improving pressure resistance and hull vibration, includes a lower fin and an upper fin. The lower fin is disposed between a second station and a fourth station in a length direction of a ship and between 10% and 20% of a design draft from a bottom of the ship in a height direction of the ship, the lower fin being inclined at an angle of 20 to 40 degrees with respect to a design draught (or base) line. The upper fin is disposed between the second station and the fourth station in the length direction of the ship and between 30% and 60% of the design draft from the bottom of the ship in the height direction of the ship, the upper fin being inclined at an angle of 10 to 30 degrees with respect to the design draught (or base) line.

Abstract: An improved tunnel configuration for tunnel mounted surface piercing propellers. The improved tunnel configuration provides a flooding suction to the tunnel to allow flooded propeller operation at speeds below planning. The tunnel is stepped whereby an upper portion of the tunnel is sized to allow the propeller to draw air at high speeds. The lower portion of the tunnel is sized to allow the propeller to be flooded resulting in smooth acceleration, improved handling in forward and reverse and a reduction of the transition period.

Abstract: A device for reducing the power demand for the propulsion of a ship, and for broad-built or non-broad-built not-very-fast ships of any type which is affixed to the hull at a short distance upstream of the propeller, comprises a fore-nozzle with fins or hydrofoils that are arranged within the fore-nozzle, wherein the fore-nozzle, at the top, can be tilted forwards by up to 8°, on a horizontal transverse axis that extends through the centre of the fore-nozzle.

Abstract: A small outboard motor powered boat comprises a hull undersurface that defines a generally flat central section, with two generally parallel-sided pontoons extending rearwardly from an upturned bow to a point about half the length of the hull aft. A stern rake section begins at a transverse line near the transom of the hull and forms a downward angle with respect to the flat central section. At speed, air is entrained between the pontoons, providing lift to the bow of the vessel, while the after portion is supported by the stern rake section. Thus, the vessel effectively rides on the pontoons and the stern rake section, reducing wetted surface and thus improving efficiency. The downwardly-extending lengthwise sides of the pontoons provide lateral surface, providing good steering characteristics.

Abstract: The present invention provides methods and apparatus for reducing sinkage and wetted surface, and thus hydrodynamic drag of a high-speed boat through the generation of aerodynamic lift while decreasing overall aerodynamic drag. At least one lift-generating front wing proximate a bow section of the boat with at least one corresponding front air channel may be provided. At least one lift-generating rear wing proximate a transom section of the boat with at least one corresponding rear air channel may also be provided. At least one of the wings may be adjustable to generate aerodynamic lift with one of: (1) a neutral; (2) a transom-lifting; and (3) a bow-lifting pitching moment about a center of inertia of the boat. At least one wing proximate the leading edge of the tunnel of a multi-hull boat may be provided to increase the operational envelope.

Abstract: A vessel (1) comprising a hull (2) with a stern (5), bow (7) and bottom (3), an air cavity (6) formed at the bottom (3) of the hull (2) and comprising a cavity top surface (27), a front wall (28) and a front section (10) located nearest to the bow (7), and an air inlet (8) located in the air cavity (6), wherein the vessel comprises a wave deflector (9) defining a lower surface (11) which is situated in the front section (10) of the air cavity (6) and at a distance from the cavity top surface (27) and extends from the front wall (28) substantially in the direction of the stern (5).

Abstract: The invention relates to a ship's bow with a central inclined plane area and starboard and port catamaran-like runners laterally thereto, the inclined plane area and runners in the midships direction pass roughly into a fictional keel line. The aim is to create such a ship's bow which, whilst being very economic when operating the ship can be used in modular manner for the most varied ship types and operating zones. To this end the runners are given a wedge-like construction and at the front runner end is provided a free flow attack opening for the inclined plane area, which is constructed with a specific inclination angle ?.

Abstract: A high-speed boat includes a hull having multiple sponsons. At least one propulsion unit is disposed on the hull. The propulsion unit is moveable with respect to the boat hull adjusting a thrust vector of the propulsion unit. In another aspect, the high-speed boat may include a hull having fore and aft portions. The fore portion includes multiple sponsons. At least one moveable step is attached to one of the sponsons, dynamically adjusting that sponson's relative contact position with respect to a water surface. In another aspect, the high-speed boat may include a hull having multiple sponsons separated by a forward hull portion. The forward hull portion includes a top surface and a bottom surface. At least one adjustable dump vent is formed on the bottom surface of the forward hull portion. The dump vent includes a door moveable with respect to the dump vent for controlling a volume of air released through the dump vent.

Abstract: The present invention provides a water-sweeping device configured to prevent the occurrence of water wall at the rear-end of a marine vehicle and particularly of an American fisherman vessel during backward movement, the device being characterized by comprising at least one water sweeping inlet, and at least one water distribution means running out of the portside or starboard sides of the vessel, said water distribution means being adapted to the water sweeping inlets.

Abstract: A boat hull has an aft swept ventilated area in at least a part of its bottom planing surface. An aft swept water flow interrupter is positioned to project downwardly from the hull forward of the ventilated area. The aft swept flow interrupter has two generally angularly related legs or sections defining a 30° to 70° included angle, increase lift on the hull, reduces wetted surface area and improves the turning characteristics of the hull.

Abstract: A ship hull includes at least one float (10) and a centre of buoyancy (CB) situated behind the centre of flotation (CF), the distance between the centre of buoyancy and centre of flotation is greater by 5% than the waterline length L of the hull.

Abstract: An entrapment tunnel watercraft vessel having three hulls consists of a main hull and two amas arranged outboard of the main hull with the keels of the three hulls being parallel. The main hull is a narrow, vee hull with variable, rearwardly decreasing deadrise. The amas have very fine bows and narrow, asymmetric deep-V hulls, with nearly vertical slab outboard sides above their keels and variable reverse deadrise on their inboard sides with the reverse deadrise angles decreasing from bow to stem. The tunnels on each side of the main hull are formed by three distinct surfaces, the sides of the main hull above its chine, the reverse deadrise inboard sides of each ama upward from their keels and a ceiling surface transversely spanning the aforementioned sides and having rearwardly increasing deadrise and rearwardly decreasing width. The tunnel ceilings slopes down from the bow to a section aft of midship where the ceiling height above the keel remains essentially constant.

Abstract: The invention is directed to a watercraft hull design that comprises a hull having a bow, stern, top, and bottom. A wedge-shaped wave spreading system is located at a forward portion of the craft. The wave-contacting surface planes of the wave spreading system are positioned substantially perpendicular to the plane of smooth water. The bottom edge of the wave spreading system is positioned near the level of smooth water when the watercraft is at cruising speed. The wave spreading system has a forward apex which forms a substantially perpendicular or vertical leading wedge to the plane of water. Since the apex and planes of the wave spreader are substantially perpendicular to the water, oncoming waves encountered by the wave spreader will tend to be deflected horizontally. Accordingly, the watercraft will more easily “cut through” waves instead of riding over them. Located rearwardly of the wave spreader, an internal hull prow is spaced from the wave spreading system, creating an air space therebetween.

Abstract: A boat hull has at least one generally transverse ventilation step formed in at least a part of its bottom planing surface open to the water. The step has a forward edge portion and a water flow interrupter is positioned to project downwardly from the hull forward of the forward edge of the step.

Abstract: A hybrid boat hull. In a first embodiment, the hybrid boat hull comprises a first and second outer elongated hulls each curved inwards to respectively define first and second keel fins which provide buoyancy and act as inclined hydrofoils when the hybrid hull is run at high speed. In a second embodiment, the hybrid boat hull further comprises an elongated central hull, which serves to dampen the effect of slamming of waves on the underside of the hybrid boat hull.

Abstract: A boat hull has at least one rocker chute formed therein open to the water forward of the hull's transom. The chute has a leading edge forward of the transom and an interceptor plate projects downwardly from the hull at said leading edge.

Abstract: A harmonic apparatus designed to affect the performance of waterborne vessels. The vibratory generator is tuned with respect to the fundamental frequency of the vessel at the onset of planning, the various wave patterns generated by the moving vessel and the kinematics of the vortex sheet. As the vessel moves through water, vibrational reactions occur that assist the performance of the vessel. The harmonic apparatus can be reconfigured to operate on several different modalities.

Abstract: A marine vessel and drive combination includes port and starboard tunnels formed in a marine vessel hull raising port and starboard steerable marine propulsion devices to protective positions relative to the keel.

Abstract: A boat hull comprises a hull body having two lateral flanks linked by a bottom surface, and at least two propulsion compartments provided in two bulges protruding below the bottom surface of the hull body. Each propulsion compartment lodges a propulsion engine located below the bottom surface of the hull body. The propulsion engines are located at the deepest position in the hull and below the water plane.

Abstract: An improved planing hull which incorporates a vee-bow (1) with outboard chines (2) designed to trap air and water between said chines. As the chines (2) extend aft they become wider and deeper (3) in the water. The vee-bow (1) ensures comfort in a seaway by deflecting waves down and outward and prohibits the bow from being buried in a wave. The outboard chines (2) can house engines and waterjets while providing buoyancy aft to match the displacement of the machinery. The chines (2) can be designed to cancel each other's wake, reducing drag and increasing lift on the hull. The resulting vessel can have much greater beam and interior accommodation with the same displacement as a typical planing boat. The hybrid hull has improved wave handling, significantly improved transverse stability, a smoother ride, and notably less draft over convention vee-hull boats.

Abstract: A system for improving the performance of a powered boat that includes both methods and apparatuses that provide a powered boat ways to stabilize, control, and optimize the powered boat's performance when the powered boat is in powered motion. The system provides capabilities of enhancing the powered boat's performance by responding to both aerodynamic and hydrodynamic effects upon the powered boat when the powered boat is in motion. Some embodiments of the system are capable of altering its way of responding to aerodynamic effects while the powered boat is in powered motion, other embodiments are capable of altering the powered boat's response to hydrodynamic effects while the powered boat is in powered motion, and still other embodiments are capable of altering the powered boat's response to both aerodynamic and hydrodynamic effects while the powered boat is in powered motion.

Abstract: A vessel for water travel that has the stability of a heavy weighted vessel when at rest in the water and the performance of a lightweight vessel when in a planed condition. The vessel comprises at least one hull structure for partially submerged flotation in a body of water and at least two hull elements affixed to or a structural part of the hull structure. The hull structure may further comprise laterally spaced hollow ballast devices that rare open at respective fore and aft ends, thus providing stability when submerged in the water and performance by the evacuation of water when in a planed condition.

Abstract: A watercraft hull has at least one bent entrapment tunnel with an aft portion whose tunnel ceiling is at a higher elevation than portions of the tunnel ceiling immediately in front of it to provide a negative angle of attack with the free surface at design planing speeds.

Abstract: A boat hull has at least one ventilating propulsion tunnel formed therein open to the water forward of the hull's transom and adapted to contain a propeller of the propulsion system. The tunnel has a leading edge forward of the transom and an interceptor plate projects downwardly from the hull at the leading edge.

Abstract: A catamaran-like one piece molded stable watercraft with sloping sides and a graduated sloping channel for supporting an individual and up to 600 pounds of gear without flipping and wherein the watercraft has a draft of no more than 6 inches fully loaded and less than 3 inches with 170 pounds of weight.

Abstract: An entrapment tunnel watercraft vessel having three hulls consists of a main hull and two amas arranged outboard of the main hull with the keels of the three hulls being parallel. The main hull is a narrow, vee hull with variable, rearwardly decreasing deadrise. The amas have very fine bows and narrow, asymmetric deep-V hulls, with nearly vertical slab outboard sides above their keels and variable reverse deadrise on their inboard sides with the reverse deadrise angles decreasing from bow to stem. The tunnels on each side of the main hull are formed by three distinct surfaces, the sides of the main hull above its chine, the reverse deadrise inboard sides of each ama upward from their keels and a ceiling surface transversely spanning the aforementioned sides and having rearwardly increasing deadrise and rearwardly decreasing width. The tunnel ceilings slopes down from the bow to a section aft of midship where the ceiling height above the keel remains essentially constant.

Abstract: A boat hull includes a dispersion tunnel extending fore and aft forming a channel within a hull bottom surface for receiving a flow of water. A gate is inserted into and out of the channel for affecting pressure on the hull bottom with movement between open and closed positions, wherein the gate is out of the channel and fully extended into the channel. By altering the depth of the gate into the channel, hull performance and wake shape are modified as desired.

Abstract: A personal watercraft having improved bottom hull shapes in general, and improved center keel shapes in particular. The center keel can have a substantial section over which the keel angle becomes sharper progressing from front to rear, and the concavities on either side of the center keel become deeper progressing from front to rear. The center keel can have a point of maximum downward slope on either side of the keel centerline, with the maximum vertically downward slope becoming greater with greater rearward distance over a section of the personal water craft bottom hull. The bottom hull can have keel troughs on either side of the keel centerline that become deeper over a section of the personal watercraft bottom hull, traveling from front to rear over that selected section of personal watercraft bottom hull. The center keel shape can provide a smoother ride and improved handling in rough water.

Abstract: A shallow draft boat has a hull that protects a propulsion propeller within a tunnel that passes only partially through the hull from stern to bow. The hull has a mechanism, such as a flap for selectively permitting or blocking water flow access to the tunnel from under the boat. The boat also has a lift mechanism preferably in the shape or adjustable parallelogram for selectively positioning a propeller of a propulsion unit substantially directly behind the tunnel or below the tunnel. The boat can operate in two modes. In one, water access to the tunnel is permitted and the propeller is positioned above the bottom of the hull and behind the tunnel. In the other, water access to the tunnel is blocked and the propeller is positioned below the bottom of the hull. This construction permits selective operation in a shallow draft mode, in a normal draft mode or in between.

Abstract: The current invention is an apparatus and method for an inner and outer dual hull boat capable of transforming between different levels of planing ability. The design is a gateway in the outer hull which allows water to pass through the void between the inner and outer hull. By controlling the position of a gate, the flow of water through the gateway in the forward moving boat can be controlled, which allows for the control of the planing or displacement capacity of the boat.

Abstract: A vessel (10) designed to operate efficiently as both a catamaran and air cushion vessel can travel at low speed (e.g. Froude number (Fn)=0–0.3) in a catamaran or displacement mode and at high speed (e.g. Froude numbers (Fn)=0.3 or more) in an air cushion or dynamically supported mode. The vessel (10) includes molded catamaran hulls (11, 12) with parabolic waterlines, a flexible, air cushion seal system (16, 17), surface piercing propellers (20) and a propulsion system (e.g. combined diesel and gas turbine). There are preferably auxiliary gas turbines for generating lift air pressure. Forward mounted independently stabilizing foils (30), can optionally facilitate ride stabilization and load compensation at high and low speeds. The foils also generate transverse roll forces to improve high speed maneuvering.

Abstract: A hydrofoil craft, particularly a method of economically modifying a conventional hull with cambered foils to obtain and calculate increased lift from dense spray and to achieve enhanced craft performance is disclosed. The present invention improves speed, fuel efficiency and rough water stability, reduced pitch and vertical accelerations. A catamaran or V-bottom hull is modified with chine mounted aerofoils, flexible dihedral cambered foils positioned beneath the water line and on either side of the bow so as to create turbulence in the forward end of a tunnel(s). Tunnels are created on the V-bottom hull by the chine mounted aerofoils. Fixed forward tunnel cambered foil(s) and/or fixed or adjustable center tunnel cambered foils at the stern end of the tunnel to generate lift from pressure caused by dense spray in the tunnel(s) may also be provided. Adjustable cambered stern foils are mounted on the transom end of the tunnels.

Abstract: An individual propelled catamaran watercraft with sloping sides and sloping channel adapted for supporting an individual without flipping and having a draft of no more than 3 inches.

Abstract: A watercraft with at least one onboard propulsion engine includes at least two hulls and a wing-like deck structure spanning the two hulls (a floating wing). Port and starboard skirts combine with the deck structure to form port and starboard planing channels. The deck structure includes an upwardly facing surface that slopes downwardly toward an aft end of the deck structure in order to provide aerodynamic lift. Preferably, a speed-responsive exhaust proportioning system vents exhaust at vertical steps in planing surfaces on the hulls to reduce drag, increase lift, and reduce thermal signature. One embodiment includes hinged laterally extending deck extensions that an operator can raise to reduce vessel breadth during docking, upwardly extending barriers on the deck extensions that reduce the escape of wind laterally, and hinged flap structures disposed rearwardly that enable an operator to adjust vessel trim.

Abstract: A vessel (10) designed to operate efficiently as both a catamaran and air cushion vessel can travel at low speed (e.g. Froude number (Fn)=0-0.3) in a catamaran or displacement mode and at high speed (e.g. Froude numbers (Fn)=0.3 or more) in an air cushion or dynamically supported mode. The vessel (10) includes molded catamaran hulls (11, 12) with parabolic waterlines, a flexible, air cushion seal system (16, 17), surface piercing propellers (20) and a propulsion system (e.g. combined diesel and gas turbine). There are preferably auxiliary gas turbines for generating lift air pressure. Forward mounted independently stabilizing foils (30), can optionally facilitate ride stabilization and load compensation at high and low speeds. The foils also generate transverse roll forces to improve high speed maneuvering.

Abstract: A watercraft with a propulsion engine includes at least one hull having an underside. A dual exhaust system includes a first exhaust conduit defining a first exhaust flow path leading to the underside (e.g., a step in a planing surface on the underside) and a second exhaust conduit defining a second exhaust flow path to atmosphere. One embodiment is self proportioning. In another embodiment, an onboard proportioning system varies first and second proportions of the exhaust flowing through respective ones of the first and second exhaust conduits according to exhaust back pressure. First and second valve mechanisms selectively restrict the first and second exhaust flow paths under computer or manual control according to pressure sensed by a back-pressure-sensing component in order to thereby direct the exhaust in desired proportions for enhanced operating characteristics and reduced thermal signature.

Abstract: A rigid concavity is formed in the underside of a hull of a water craft. Air enters into the concavity when the water craft is moving forward. Supplemental air is introduced into the concavity by an air scoop mounted to the bow. A one-way valve in an air passageway between the air scoop and the concavity prevents air from flowing from the concavity to the air scoop. A first stern plate mounted at a slight downward angle causes air to flow under the stern in the form of small bubbles and increases the back pressure presented to the flow of water and air through the concavity. A pair of adjustably mounted stern plates may also be provided on opposite sides of the motor to control the amount of back pressure. The airflow through the rigid concavity reduces drag so that the water craft can travel at higher speeds.

Abstract: A hull system for boats that includes pairs of longitudinally extending strakes with a cross-section that includes a downwardly extending fin member with an adjacent flat horizontal section to provide running and idle stability. Steps with a projected V-shape pint forward and include air inlets with the distal ends. Channels run adjacent to the drop off wall of the steps to trap air forming an air cushion that tends to lift the moving hull. The resulting hull system provides optimal performance while running and still maintains good stability from oscillation when idle. A peripheral chin has a substantially triangular cross-section that extends vertically downwardly inside the body of water over which the boat floats.

Abstract: A water sports performance boat includes a hull having a sharpened angle keel for cutting into the water. Reverse chines are carried on port and starboard sides and extending from a forward portion of the hull to an aft portion for inducing a lifting of the bow at generally low boat speeds and for providing a stabilizing effect. Port and starboard spray pockets are located at the aft portion of the hull for reducing a side spray of water near the transom. Performance strakes are formed within the hull with each extending from an aft position rearwardly to the transom. An elliptical shaped dispersion tunnel formed along the keel within an aft most portion of the hull extends through the transom and provides a desirable wake shape.

Abstract: A watercraft steered under power by water-jet propulsion utilizes a water intake ramp in its hull to create a nozzle-like effect to accelerate water loading to the jet pump through a ventral water inlet when under power. The hull has a pair of longitudinal stabilizers that form a tunnel in which the ramp is located. A canopy, which can be removable, encloses a passenger compartment with a steering wheel and one or more passenger seats. Two wings flank the passenger compartment and a pair of hull ramps run steeply downward from the leading edge of each of the wings and extends to the bottom of the hull while a pair of air scoops flanks each side of the passenger compartment and is located above the pair of wings. The forward-most beginnings of the pair of stabilizers relative to a nose section and the pair of wings ride above the surface of the water when the watercraft is under power and the watercraft rides on the back of the pair of stabilizers.

Abstract: A hydrofoil craft, particularly a method of economically modifying a conventional hull with cambered foils to obtain and calculate increased lift from dense spray and to achieve enhanced craft performance is disclosed. The present invention improves speed, fuel efficiency and rough water stability, reduced pitch and vertical accelerations. A catamaran or V-bottom hull (20) is modified with chine mounted aerofoils (32, 33, 28, 28A), flexible dihedral cambered foils positioned beneath the water line and on either side of the bow (30, 31) so as to create turbulence in the forward end of a tunnel(s) (26). Fixed forward tunnel cambered foil(s) (28) and/or fixed or adjustable center tunnel cambered foils at the stern (28A) end of the tunnel (26) to generate lift from pressure caused by dense spray in the tunnel(s) (26) may also be provided.

Abstract: A watercraft includes at least one hull having at least one planing surface, at least one vertical step in the planing surface, and an onboard propulsion engine. An exhaust-venting system is provided for venting exhaust from the onboard propulsion engine at the vertical step in the planing surface while under way in order to introduce gas along the planing surface. The hull of one embodiment takes the form of an M-shaped boat hull. The invention also applies to any of various other watercraft hulls, including watercraft with multiple hulls such that each of the multiple hulls includes one or more planing surfaces with one or more vertical steps at which exhaust is vented.