The present invention provides a hull-conversion device and method for modifying the underside of a watercraft, more specifically a multihull watercraft. The hull-conversion device comprising a water diverting surface, a kinematic assemblage, and a frame. The hull-conversion device may be operable to adjust the watercraft's characteristics in displacement mode and planing mode. The hull-conversion device may function to provide a more stable, controllable, and efficient platform for operating a multihull watercraft, and provide a suitable wake for towable water sports.

A marine vessel or watercraft may be provided with an aft extension that, in one configuration of the watercraft, alters the wake of the watercraft, for example by reducing the height of the wake, and which may include a sealable opening to provide crew or payload access into or out of the watercraft at a location (e.g., aft of the transom) that may be difficult for an observer to perceive. The aft extension may be positioned above the watercraft's waterline when the watercraft is in another configuration such that it does not contact with the water to reduce adverse impact on performance characteristics, such as drag, of the hull when the watercraft is in that configuration. The watercraft may transition between the two configuration by selectively varying the displacement of the watercraft or by articulating of the aft extension.

A marine vessel or watercraft may be provided with an aft extension that, in one configuration of the watercraft, alters the wake of the watercraft, for example by reducing the height of the wake, and which may include a sealable opening to provide crew or payload access into or out of the watercraft at a location (e.g., aft of the transom) that may be difficult for an observer to perceive. The aft extension may be positioned above the watercraft's waterline when the watercraft is in another configuration such that it does not contact with the water to reduce adverse impact on performance characteristics, such as drag, of the hull when the watercraft is in that configuration. The watercraft may transition between the two configuration by selectively varying the displacement of the watercraft or by articulating of the aft extension.

To provide an amphibious vehicle that can reduce wave drag at the time of hydroplaning and can improve propulsion performance of the vehicle body. An amphibious vehicle according to the present invention includes a vehicle body capable of moving on water and on land, a front flap with a rear end being fixed to a lower end of the vehicle body, a rear flap with a front end being fixed to a rear part of the vehicle body, and a pair of keels provided along a travel device provided on both sides of the vehicle body on a bottom surface of the vehicle body.

To provide an amphibious vehicle that can reduce wave drag at the time of hydroplaning and can improve propulsion performance of the vehicle body. An amphibious vehicle according to the present invention includes a vehicle body capable of moving on water and on land, a front flap with a rear end being fixed to a lower end of the vehicle body, a rear flap with a front end being fixed to a rear part of the vehicle body, and a pair of keels provided along a travel device provided on both sides of the vehicle body on a bottom surface of the vehicle body.

An amphibious vehicle, which enables wave making resistance upon traveling on water to be reduced and propulsive performance of its vehicle main body to be improved, is to be provided. An amphibious vehicle of the present invention includes: a vehicle main body that is movable on water and on land; a rear portion flap having a front end portion fixed to a rear portion of the vehicle main body; and end plates respectively provided at both side end portions of the rear portion flap.

A moveable exhaust trim tab for a motorized boat directs exhaust gas and cooling liquid into the water, changing the size and shape of the wake and reducing engine noise. The device comprises a trim tab base having a lip and a cap attached to the trim tab base to form a cavity between the lip and the cap into which the boat's exhaust is directed. The cavity has various apertures that permit the exhaust to exit the cavity and, in some embodiments, permit water to enter the cavity from below. The device may comprise baffles, outlets, inlets, and directional collars to change the flow of the exhaust. The trim tab is attached to the boat with an actuator that lets the trim tab to be adjusted at an angle relative to the boat.

A moveable exhaust trim tab for a motorized boat directs exhaust gas and cooling liquid into the water, changing the size and shape of the wake and reducing engine noise. The device comprises a trim tab base having a lip and a cap attached to the trim tab base to form a cavity between the lip and the cap into which the boat's exhaust is directed. The cavity has various apertures that permit the exhaust to exit the cavity and, in some embodiments, permit water to enter the cavity from below. The device may comprise baffles, outlets, inlets, and directional collars to change the flow of the exhaust. The trim tab is attached to the boat with an actuator that lets the trim tab to be adjusted at an angle relative to the boat.

A system including a convex-shaped member, an actuator and a computer. The convex-shaped member includes a forward facing surface, a first end and a second end. While in a deployed state, the forward facing surface curves outward between the first end and the second end in a direction away from a point rearward of the forward facing surface, and the convex-shaped member (i) adjusts attitude or motion of a marine vessel, (ii) deflects oncoming water, and (iii) extends at least partially below a bottom surface of the marine vessel. The actuator (i) is coupled to the convex-shaped member, and (ii) while connected to the marine vessel, is configured to move the convex-shaped member. The computer is configured to control the actuator to transition the member between the deployed state and a retracted state.

A system including a convex-shaped member, an actuator and a computer. The convex-shaped member includes a forward facing surface, a first end and a second end. While in a deployed state, the forward facing surface curves outward between the first end and the second end in a direction away from a point rearward of the forward facing surface, and the convex-shaped member (i) adjusts attitude or motion of a marine vessel, (ii) deflects oncoming water, and (iii) extends at least partially below a bottom surface of the marine vessel. The actuator (i) is coupled to the convex-shaped member, and (ii) while connected to the marine vessel, is configured to move the convex-shaped member. The computer is configured to control the actuator to transition the member between the deployed state and a retracted state.