There is provided a casing for a towable sonar apparatus, comprising: a tubular member, wherein the tubular member comprises a foam member or a mesh member; a first layer around the tubular member, wherein the first layer is porous.

There is provided a casing for a towable sonar apparatus, comprising: a tubular member, wherein the tubular member comprises a foam member or a mesh member; a first layer around the tubular member, wherein the first layer is porous.

A positioning and rescue device for an unmanned underwater vehicle, comprising a battery (1), a switch (2), a protective resistor (3), an electromagnetic relay (4), a master control chip (5), a GPS positioning system (6), an igniter (7), a partition (8), an air bag (9), a shell (10), and a rope (11). The battery (1), the switch (2), the protective resistor (3), the electromagnetic relay (4) and the master control chip (5) are sequentially connected by means of wires to form a series circuit, and the igniter (7) and the GPS positioning system (6) are separately connected to the master control chip (5) by means of wires; two normally open contacts of a control loop of the electromagnetic relay (4) are respectively connected to two ends of a general power supply (15).

A positioning and rescue device for an unmanned underwater vehicle, comprising a battery (1), a switch (2), a protective resistor (3), an electromagnetic relay (4), a master control chip (5), a GPS positioning system (6), an igniter (7), a partition (8), an air bag (9), a shell (10), and a rope (11). The battery (1), the switch (2), the protective resistor (3), the electromagnetic relay (4) and the master control chip (5) are sequentially connected by means of wires to form a series circuit, and the igniter (7) and the GPS positioning system (6) are separately connected to the master control chip (5) by means of wires; two normally open contacts of a control loop of the electromagnetic relay (4) are respectively connected to two ends of a general power supply (15).

Disclosed is a hull device designed to be reversibly attached to an outer surface of a ferromagnetic structure of a marine or submarine system or vessel. The device includes at least one attachment surface suitable for attaching the device to the structure, and a plurality of permanent magnets arranged in the vicinity of the attachment surface in order to attach the device to the structure.

Disclosed is a hull device designed to be reversibly attached to an outer surface of a ferromagnetic structure of a marine or submarine system or vessel. The device includes at least one attachment surface suitable for attaching the device to the structure, and a plurality of permanent magnets arranged in the vicinity of the attachment surface in order to attach the device to the structure.

Techniques are disclosed for providing retractable control fins on an underwater vehicle. The retractable control fins can be extended away from a main hull portion of the underwater vehicle and retracted inwards to a stowage region within the hull portion to protect the fins from damage and reduce an overall outer diameter (e.g., in the case of a cylindrical body) of the underwater vehicle. In some embodiments, the control fins are folded inwards to reduce the vehicle diameter. In other embodiments, the control fins are pulled inwards using a rotating structure designed to slide the control fins through an opening and into an inner portion of the hull to reduce the vehicle diameter. The retraction of the fins through the various retraction mechanisms reduces the envelope diameter of the underwater vehicle.

Techniques are disclosed for providing retractable control fins on an underwater vehicle. The retractable control fins can be extended away from a main hull portion of the underwater vehicle and retracted inwards to a stowage region within the hull portion to protect the fins from damage and reduce an overall outer diameter (e.g., in the case of a cylindrical body) of the underwater vehicle. In some embodiments, the control fins are folded inwards to reduce the vehicle diameter. In other embodiments, the control fins are pulled inwards using a rotating structure designed to slide the control fins through an opening and into an inner portion of the hull to reduce the vehicle diameter. The retraction of the fins through the various retraction mechanisms reduces the envelope diameter of the underwater vehicle.

A flange for a pressure vessel includes a rim, a sealing seat, and an undercut fillet. The rim has an annular surface for abutting an annular end of a cylindrical wall of the pressure vessel. The sealing seat has a cylindrical surface for abutting an inner surface of the cylindrical wall of the pressure vessel nearby the annular end. The undercut fillet is disposed between the rim and the sealing seat. A concave surface of the undercut fillet extends the annular surface of the rim radially inward and then curves back outward to intersect the cylindrical surface of the sealing seat. The undercut fillet of the flange helps distribute stress produced from a pressure differential between the inside and outside of the pressure vessel.

A flange for a pressure vessel includes a rim, a sealing seat, and an undercut fillet. The rim has an annular surface for abutting an annular end of a cylindrical wall of the pressure vessel. The sealing seat has a cylindrical surface for abutting an inner surface of the cylindrical wall of the pressure vessel nearby the annular end. The undercut fillet is disposed between the rim and the sealing seat. A concave surface of the undercut fillet extends the annular surface of the rim radially inward and then curves back outward to intersect the cylindrical surface of the sealing seat. The undercut fillet of the flange helps distribute stress produced from a pressure differential between the inside and outside of the pressure vessel.