A belt for reducing the drag of a hull of a floating vessel, whereby the belt includes a belt body extending in a length direction (L), whereby the belt has, a sequence of bubble generators which are embedded in the belt body, whereby the belt has an air channel for supplying pressurized air to the bubble generators, whereby the air channel extends in the length direction (L), whereby the bubble generators are connected to the air channel, whereby the belt body is made of a flexible material. Also disclosed is a device having such a belt and a method of reducing the drag of a hull of a floating vessel using such a belt.

An apparatus including a controllable fluid-contacting surface is provided. In another aspect, the present apparatus includes a flexible membrane and multiple actuators each having an output shaft or activation member coupled to a water-contacting membrane, with the shafts extending in a direction offset from the nominal outer surface of the membrane. A further aspect of the present apparatus includes an underwater vessel including a propulsion source, a flexible membrane having a water-contacting outer surface and an electronic controller including programmable software for actuating the actuators.

In order to provide an arrangement with at least one rudder and with at least one accommodating space for a propeller, which accommodating space is formed in the direction of travel of the watercraft in front of the rudder and allows for a reduction of a propulsion power requirement of a watercraft with such an arrangement, it is proposed that, in the direction of travel in front of the accommodating space of the propeller, at least one pre-nozzle comprising at least one guide surface and at least one side fin is arranged on the rudder.

A flat-bottomed vessel for transporting persons or goods, the vessel including a drag reduction system attached to the bottom of the vessel. The drag reduction system includes: two or more turbulence members extending perpendicular to the longitudinal direction of the vessel for generating an area with turbulent flow downstream to the turbulence members at the bottom of the vessel during movement. Additionally, for each turbulence member an air injector can be used to inject an air flow at or near to the turbulence members.

Hull with variable geometry for a vessel (11), comprising a completely immersed part (12), configured to provide part of the buoyancy thrust and integral with an emerged part (13) of the hull by means of one or more uprights (14), and one or more immersed wing surfaces (15) which, in a situation in which the vessel travels at a sufficiently high speed, are configured to provide the remaining part of the vertical thrust required to keep the vessel (11) above the surface of the water at a predetermined height; the hull comprises one or more supports (16a, 16b, 16c) connected to the wing surfaces (15) and associated with floating elements (17a, 17b, 17c) which are mobile with respect to the completely immersed part (12); the floating elements (17a, 17b, 17c) are fixed to the supports (16a, 16b, 16c) or mobile with respect to the supports (16a, 16b, 16c), therefore the floating elements (17a, 17b, 17c) are substantially cooperating with the completely immersed part (12) and with the wing surfaces (15); the wing surfaces (15) are configured to move with respect to the completely immersed part (12) or to remain fixed with respect thereto and the floating elements (17a, 17b, 17c) are configured to increase their immersion as the speed of the vessel decreases, and therefore provide the vertical thrust to maintain or adjust the distance of the vessel from the water in a manner that is optimal and functional for the use of the vessel, even at reduced speeds or when the vessel is stationary.

Wakeboat hull control systems and methods are provided to permit the accurate reproduction of a wake behind a wakeboat. The onboard wake control system receives data from a draft measuring system. Incorporation of the data from the draft measuring system permits accurate reproduction of a wake behind the wakeboat after a change in an onboard variable such as the number, weight or position of passengers, the weight or position of cargo and the position of trim tabs or amount/location of ballast.

A method of monitoring accelerations on a vessel includes measuring acceleration on the vessel using one or more sensors. The one or more sensors are communicatively coupled to a computing unit. Real-time acceleration information representative of an acceleration on the vessel based at least in part on the measured acceleration from the one or more sensors is generated. Acceleration prediction information representative of predicted wave slam using the computing unit is generated. Using the acceleration prediction information, automatic control of trim, steering, or throttle controls of the vessel is performed in a fashion computed to reduce the effects of the predicted wave slam.

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.

A wake control system aft of the driveshaft, propeller, and rudder of a vessel includes a fin base and at least one fin slidingly engaged with the fin base. The fin(s) are vertically oriented and extend down into the water surface. The fins are transversely adjustable along the fin base to redirect a wake generated by the boat. In other embodiments, the control system comprises a starboard fin tab adjacent to a port fin tab, each of the independent fin tabs hingeably attached to the aft section of the hull, at the transom. Each fin tab includes at least one extending fin. Fin tabs are selectively deployable and retractable into and out of the water surface to redirect a wake generated by the vessel from one side to the other. A novel underwater exhaust system redirects exhaust depending on speed of the vessel and complements the wake control system.