A pontoon boat includes port and starboard pontoons and cross members connecting the pontoons. A shock absorber may be installed at each point of connection of the pontoons to the cross members. A cross member may be embodied as a double-webbed beam having first and second parallel flanges and first and second webs disposed between and connected to the flanges. Each pontoon may include a two-stage lifting strake having a first surface and a second surface inclined from the first surface.

A pontoon boat includes port and starboard pontoons and cross members connecting the pontoons. A shock absorber may be installed at each point of connection of the pontoons to the cross members. A cross member may be embodied as a double-webbed beam having first and second parallel flanges and first and second webs disposed between and connected to the flanges. Each pontoon may include a two-stage lifting strake having a first surface and a second surface inclined from the first surface.

A truss system may include a plurality of beams. Each beam of the plurality of beams may have various cross-sectional sizes in a same plane. Additionally, the plurality of beams may have a geometric arrangement such that a structural weight at required strength level may be reduced to achieve optimal design.

A quick connect system for a boat connects the deck of the boat to the hull of the boat. The deck sits on top of the hull. The hull is preferably inflatable, and preferably in two opposing, symmetrical hull sections being a left hull and a right hull. Each hull preferably has two parallel inflatable tubes that extend from the rear of the hull to the front. The deck is preferably a multi-piece system having a spaced apart front deck rear deck. An elevated casting platform extends between the deck sections and is supported by legs. The hull and deck have a series of aligned rigid tube receivers and loops that receive a series of rails. The rails are slideable into the loops and rigid tube receivers to secure the deck to the keel, and to provide a quick mechanism to disassemble the deck from the tubes.

Implementations described and claimed herein provide an underwater vehicle includes a vehicle body having a frame enclosed by a fairing. The vehicle body extends between a proximal end and a distal end and defining an interior. A nose is disposed at the proximal end of the vehicle body. The nose has a tow system configured to move between a tow position and a stow position. A propulsion system is disposed at the distal end of the vehicle body. The propulsion system includes a plurality of control fins and a thruster. A power distribution system is housed in the interior of the vehicle body. The power distribution system includes a first power system housed in a first pressure vessel and a second power system housed in a second pressure vessel. The first pressure vessel is isolated from the second pressure vessel.

Semi-submersibles are subjected to loading from waves, causing racking, longitudinal shear and parallelogramming, or differential movement of the pontoons. The cyclic wave loading makes the various connections, where stress concentrations occur, susceptible to fatigue damage throughout the hull structure. This is most evident at the connections between the braces and the main hull structure. A revised brace to main hull connection with reduced bending stiffness is employed to reduce the moment being transferred from the brace to the hull, thereby reducing the bending stress and susceptibility to fatigue damage. This improved connection employs an internal member to transfer the loads between the brace and hull structure mainly as tension and compression. As a consequence of the improved fatigue performance, the structural weight of the connection can be greatly reduced, thus increasing the capacity with which the semi-submersible hull can operate.

Semi-submersibles are subjected to loading from waves, causing racking, longitudinal shear and parallelogramming, or differential movement of the pontoons. The cyclic wave loading makes the various connections, where stress concentrations occur, susceptible to fatigue damage throughout the hull structure. This is most evident at the connections between the braces and the main hull structure. A revised brace to main hull connection with reduced bending stiffness is employed to reduce the moment being transferred from the brace to the hull, thereby reducing the bending stress and susceptibility to fatigue damage. This improved connection employs an internal member to transfer the loads between the brace and hull structure mainly as tension and compression. As a consequence of the improved fatigue performance, the structural weight of the connection can be greatly reduced, thus increasing the capacity with which the semi-submersible hull can operate.

A chassis module for a vessel, the chassis module having: a frame; a left linkage arrangement including at least one left hull connection and configured to movably couple the frame to at least one left hull when the left hull connection is connected to the left hull; a right linkage arrangement including at least one right hull connection and configured to movably couple the frame to at least one right hull when the right hull connection is connected to the right hull; at least one left support mount and at least one right support mount for respectively connecting to a respective support providing support for the frame relative to the respective left or right hull when hulls are connected to the hull connections; the frame having a plurality of body attachments to facilitate attachment of the chassis module to a body of a vessel.