Embodiments described herein provide recirculation-based alternating blowdown sea chest. The sea chest has a cover assembly with a plurality of grates thereon. Each grate is connected with a pipe in fluid communication with a pump. The pump provides suction while a plurality of valves modulate the flow of water through the system. A recirculation pipe promotes the blowdown of fluids within the system and permits tandem function of water intake and expulsion resulting in maximum efficiency of the sea chest with continuous functionality while in use.

A vessel has a compartment (34) for containing water, which compartment (34) has at least one opening (31) in a wall (30) thereof for allowing water to pass therethrough. The compartment (34) comprises an assembly (1) of a grating (10) and at least one anti-biofouling source (20), the grating (10) being positioned in the opening (31) for blocking items from passing through the opening (31) along with the water, and comprising a number of elements and spaces between the elements, and the anti-biofouling source (20) being configured to emit ultraviolet light during operation thereof for realizing anti-biofouling of at least a portion of the grating (10). At least one of the elements of the grating (10) is at least partially transparent to the ultraviolet light, enabling a design of the assembly (1) in which anti-biofouling of the entire grating (10) may be guaranteed.

A threaded connection body is welded to the wall of a pipe, seachest or other flooded cavity within the hull of a ship or floating offshore installation. A sealed cutting apparatus is mounted via a valve unit n the connection body and a cutter extended through the open valve to form an opening in the wall. After retracting the cutter and closing the valve, the cutting apparatus is replaced by an inspection unit having a camera which is extended through the valve and the opening to inspect the cavity. After retracting the camera and closing the valve, the inspection unit is replaced by a plug deployment unit which advances a plug through the valve and screws it into the connection body. The valve unit can then be removed and replaced with a cap so that the plug and the cap provide a double seal to the connection body.

A hull for a semi-submersible wind turbine platform capable of floating on a body of water and supporting a wind turbine includes a keystone and at least three bottom beams extending radially outward of the keystone. Each bottom beam has a primary beam portion and a column base portion, wherein the column base portion is configured to support an outer column of the hull thereon, and wherein the primary beam portion defines a first ballast compartment therein. The first ballast compartment is in fluid communication with water in the body of water in which the hull is floating.

An isolation method, and apparatus, for isolating and temporarily sealing closed an opening of a marine vessel to prevent ingress of fluid into or through the opening, sealing an internal side of the opening from an external side of the opening. A positioning line is provided between a connection point and the sealing apparatus, with the positioning line being tensioned to pull the sealing apparatus towards the opening. The method is performed entirely diverlessly, with no personnel required in or under the water at any stage of the method, including during connecting the positioning line to the connection point and pulling the sealing apparatus onto and/or into the opening.

A sea chest, discharge tank and black water discharge tank are disclosed, each comprising a chamber preferably formed integral with a vessel hull to eliminate multiple inlets/outlets to the vessel. The discharge tanks employ a removable standpipe to effectively move a thru-hull opening from beneath the vessel water line to a position above the vessel water line. A sea chest includes a chamber for placement of a UV light to treat incoming water.

A threaded connection body (20) is welded to the outer surface of the wall (10) of a pipe, seachest or other flooded cavity (4) within the hull of a ship or floating off-shore installation. A sealed cutting apparatus (50) is mounted via a valve unit (30) on the connection body and a cutter extended through the open valve (34) to form an opening (18) in the wall (10). After retracting the cutter and closing the valve (34), the cutting apparatus is replaced by a sealed inspection unit (70) having a camera (71) which is extended through the valve and the opening to inspect the cavity (4). After retracting the camera and closing the valve, the inspection unit is replaced by a plug deployment unit (100) which is used to advance a plug (120) through the open valve and screw it into the connection body (20). The valve unit (30) can then be removed and replaced with a cap (90) so that the plug and the cap provide a double seal to the connection body.

The embodiments disclosed herein provide a sea chest maintenance access trunk to a sea chest positioned within a vessel. The access trunk is in fluid communication with the sea chest. A watertight closure is selectively opened or closed and is positioned above the waterline to prevent fluid from entering the vessel when in an open configuration. It also permits diver or ROV access to the sea chest when in an open configuration.

A negative pressure aeration system, created by atmospheric siphon pressure above the waterline and mechanical pump suction below the waterline, which impedes the growth of organic matter. A waterfall flow in vacuum effect is created within a system that aerates the raw water as it falls through the air chamber of the system housing, which assists in the suppression of organic growth by reducing the contact surface area within the system. A chemical tank allows an anti-fouling chemical to be added to the entire system and a power supply allows flexible electrodes driven by a vacuum to create a further anti-fouling benefit throughout the components of the system.

A marine vessel (10) includes: a hull (11); an electric propulsion portion (15) that propels the hull (11); a water tank portion (20) that is provided on the hull (11) and is capable of storing water in the water tank portion; a float portion (40) that is provided within the water tank portion (20) so as to be movable upward and downward; and a battery case (30) that is attached to the float portion (40) and is capable of storing a detachable portable battery (35) which becomes an electric power source of the electric propulsion portion (15) in the battery case.