An example underwater vehicle includes a first section detachably coupled to a second section that is positioned forward of the first section, and a hinge detachably coupling the first section to the second section, where the hinge creates a pivot between the first section and the second section. The underwater vehicle includes a lock having a locked position and an unlocked position, where, in the locked position, the lock couples the first section and the second section together, and where, in the unlocked position, the second section is capable of decoupling from the first section. The underwater vehicle also includes a drag fin associated with the second section that is movable to an extended position away from the second section to create a drag force which causes the second section to pivot about the hinge, away from the first section, when the underwater vehicle is traveling through a fluid medium.

An example underwater vehicle includes a first section detachably coupled to a second section that is positioned forward of the first section, and a hinge detachably coupling the first section to the second section, where the hinge creates a pivot between the first section and the second section. The underwater vehicle includes a lock having a locked position and an unlocked position, where, in the locked position, the lock couples the first section and the second section together, and where, in the unlocked position, the second section is capable of decoupling from the first section. The underwater vehicle also includes a drag fin associated with the second section that is movable to an extended position away from the second section to create a drag force which causes the second section to pivot about the hinge, away from the first section, when the underwater vehicle is traveling through a fluid medium.

A variable diameter conical nose is provided. The conical nose includes a cone formed from a circular sheet of ductile material having a sector removed. The formed cone has a first overlapping portion and a second overlapping portion overlying the first overlapping portion. The first overlapping portion is fixed and the second overlapping portion is free to move. The conical nose includes an actuator capable of varying the diameter of the cone by moving the second overlapping portion relative to the first overlapping portion.

A marine vessel comprising: at least one buoyant tubular foil; and at least one baffle plate positioned about the perimeter of the at least one buoyant tubular foil so as to protrude into the flow of water passing by the perimeter of the at least one buoyant tubular foil, whereby to create a high-pressure zone fore of the at least one baffle plate and a low-pressure zone immediately aft of the at least one baffle plate, whereby to create a dense stream of supercavitated water immediately aft of the at least one baffle plate.

A water craft comprising: an elongated hull comprising a passageway having an inlet and an outlet; a pump jet disposed within said passageway intermediate said inlet and said outlet; said pump jet being configured to receive water entering said passageway through said inlet and pump said water out of said outlet, whereby to propel said hull through water; a plurality of nozzles disposed on the outer surface of said hull, aft of said inlet, wherein said plurality of nozzles are configured to release a friction-reducing fluid, whereby the friction-reducing fluid displaces water from the surface of said hull so as to diminish friction on the outer surface of said hull and facilitate high speeds.

A marine vessel comprising: at least one buoyant tubular foil; and at least one baffle plate positioned about the perimeter of the at least one buoyant tubular foil so as to protrude into the flow of water passing by the perimeter of the at least one buoyant tubular foil, whereby to create a high-pressure zone fore of the at least one baffle plate and a low-pressure zone immediately aft of the at least one baffle plate, whereby to create a dense stream of supercavitated water immediately aft of the at least one baffle plate.

A submersible vessel comprising: an elongated hull; at least one propeller mounted on a forward end of said hull and adapted to move said hull through water; said at least one propeller being of a size and configuration such that when it is rotated at an appropriate speed, it generates supercavitated water flowing from said at least one propeller and thence along an outer surface of said hull so as to diminish friction on the outer surface of said hull and facilitate high underwater speeds.

A marine vessel comprising a command module, first and second buoyant tubular foils, and first and second struts for connecting the first and second buoyant tubular foils to the command module, respectively, wherein the first and second buoyant tubular foils provide substantially all buoyancy required for the marine vessel, and wherein the marine vessel further comprises first and second engines enclosed within the first and second buoyant tubular foils, respectively, and first and second propulsion units connected to the first and second engines, respectively, for moving the marine vessel through water, and means for reducing drag on the vessel as the vessel moves through water.

Projectile launch apparatus (20) for use in a fluid environment. The apparatus (20) comprises a launch tube (21) having a supercavitating projectile (24) with cavitator (29) received within the launch tube (21). A means for generating expulsion gas (not visible) is arranged to provide expulsion gas to propel the projectile (24) from the launch tube (21), with means for bleeding expulsion gas (31, 32) being provided to bleed a portion of expulsion gas around the projectile (24). This allows expulsion gases to contribute to the formation of the gas cavity around the supercavitating projectile (24) as the projectile (24) is launched from the launch tube (21). Particularly suited to the deployment of supercavitating projectiles underwater, such as in underwater mine disposal applications.