A spoiling apparatus for triggering a turbulent transition by autonomous disturbance and spoilers. The spoilers are mounted in multiple grooves in the circumferential direction of a navigating body, when a flow autonomously undergoes a turbulent transition, the spoilers remain in the grooves, the surface of the navigating body is free of protrusion, thus causing no additional flow resistance. A rated critical Reynolds number is set, in a case of a reduced flow speed and reduced density, the flow is a laminar flow, at which time the pressure applied to the spoilers by the flow is reduced, and the spoilers are ejected under the effect of compression springs. When ejected, the spoilers disturb the flowing of the bottom layer of the flow, and trigger the laminar flow into a turbulent flow. By setting the rebounding force of the compression springs, the spoiling apparatus is turned on automatically when a disturbance-triggered turbulent transition is required and is turned off when not required, thus implementing the autonomous control of turbulent transitions.

A ballast water-free ship using a difference in the depth of the bottom shell plate between the bow/stern and the midship section and a construction method thereof. A stepped portion is formed between either the bow or the stern and the midship section, such that the depth of the bottom shell plate of either the bow or the stern differs from the depth of the bottom shell plate of the cargo containment in the midship section, so that cargo can be loaded and unloaded without ballast water operation.

The invention relates to boat building and can be used in the building and modification of sea-going high-speed keeled monohull sailboats or sail and motor boats with a high sail power to weight ratio, where a single, narrow, wave-penetrating displacement hull is used. To provide for the stable controlled movement of a keeled monohull sailboat or sail and motor boat in wave penetration mode, i.e. in a low wave/hydrodynamic resistance displacement mode, both when heeling and when upright (at the same time effectively counteracting heeling and rocking on all courses), and to provide for the damping of the energy of a broken wave and also for the ability of the boat to self-right to an even keel from a “sail-on-water” position, a stabilized hull for a keeled monohull sailboat or sail and motor boat is configured with an overall width of not more than 50% of the length of the hull and has, in the bottom part thereof, a vertically oriented narrow section (4) of low wave/hydrodynamic resistance, which runs longitudinally along the full length of the boat, is symmetrical about the centreline thereof and has a displacement segment (5) comprising a keel (8) with a heavy bulb, wherein the displacement of the segment is equal to the full unladen weight of the boat. The hull further comprises two narrow longitudinally oriented sponsons (6 and 7), arranged symmetrically in relation to the centreline of the boat, which do not bear the weight of the boat and which have a streamlined shape of low wave/hydrodynamic resistance. Said sponsons are situated above the waterline at the maximum width of the hull, forming two tunnel cavities (10) above the waterline to dampen the energy of a wave broken by the bow and the sponsons.

A watercraft includes a vessel body, a marine propulsion device and a guide. The marine propulsion device is attached to the vessel body and includes a water stream generator that propels the vessel body. The guide is provided on the vessel body and extends astern of the vessel body and toward a center of the vessel body in a width direction of the vessel body from a position located sideward of the water stream generator. The guide inwardly directs water flowing on one lateral side of the vessel body such that confluent timing of the water flowing on the one lateral side of the vessel body and water flowing on the other lateral side of the vessel body is caused to occur earlier than when the guide is not provided on the vessel body.

A watercraft includes a vessel body, a marine propulsion device and a guide. The marine propulsion device is attached to the vessel body and includes a water stream generator that propels the vessel body. The guide is provided on the vessel body and extends astern of the vessel body and toward a center of the vessel body in a width direction of the vessel body from a position located sideward of the water stream generator. The guide inwardly directs water flowing on one lateral side of the vessel body such that confluent timing of the water flowing on the one lateral side of the vessel body and water flowing on the other lateral side of the vessel body is caused to occur earlier than when the guide is not provided on the vessel body.

Recreational watercraft and methods of operating recreational watercraft are described. Recreational watercraft can include an aluminum hull, a plurality of ballast tanks, a first surface defining a first opening that extends from an interior of a ballast tank of the plurality of ballast tanks to an exterior of the hull, a valve configured to selectively open or close the first opening, and a second surface defining a second opening that is fixed permanently open and extends from an interior of the ballast tank through a bottom portion of the hull to an exterior of the hull.

Recreational watercraft and methods of operating recreational watercraft are described. Recreational watercraft can include an aluminum hull, a plurality of ballast tanks, a first surface defining a first opening that extends from an interior of a ballast tank of the plurality of ballast tanks to an exterior of the hull, a valve configured to selectively open or close the first opening, and a second surface defining a second opening that is fixed permanently open and extends from an interior of the ballast tank through a bottom portion of the hull to an exterior of the hull.

A floatation system for a marine vessel having a deck. The floatation system includes three pontoons each having a cylindrical portion extending between forward and aft ends. The three pontoons include a starboard pontoon, a port pontoon, and a center pontoon positioned therebetween. Support members are coupled to the deck and to the three pontoons such that the three pontoons are interposed. Outer strakes each having a tip and an elongated portion, the elongated portions each extending along an outer length between forward and aft ends, are each coupled to one of the starboard pontoon and the port pontoon. Inner strakes each having a tip and an elongated portion, the elongated portions each extending along an inner length between forward and aft ends, are each coupled to the center pontoon. The aft ends of the outer strakes are aft of the aft ends of the inner strakes.

A floatation system for a marine vessel having a deck. The floatation system includes three pontoons each having a cylindrical portion extending between forward and aft ends. The three pontoons include a starboard pontoon, a port pontoon, and a center pontoon positioned therebetween. Support members are coupled to the deck and to the three pontoons such that the three pontoons are interposed. Outer strakes each having a tip and an elongated portion, the elongated portions each extending along an outer length between forward and aft ends, are each coupled to one of the starboard pontoon and the port pontoon. Inner strakes each having a tip and an elongated portion, the elongated portions each extending along an inner length between forward and aft ends, are each coupled to the center pontoon. The aft ends of the outer strakes are aft of the aft ends of the inner strakes.

A water flow deflection device attached to a side of a watercraft to enhance the watercraft's wake. The device having a narrow, elongated base with two ends and a base width, the base aligned along the side of the watercraft when the device is attached to the watercraft. A deflector attached to the base between the two ends and having a face spanning between a leading end and an opposing end, the leading end extending outwardly from the base. The deflector face having a surface area configured to deflect water and a deflector width greater than the base width. The base removably attachable to the watercraft by a plurality of suction cup assemblies, wherein a greater number of suction cup assemblies located between the first end and the leading end of the deflector than between the second end and the leading end of the deflector.