Buoyancy control for underwater survey equipment - with external coil pipe with piston and ballast fluid

摘要

The underwater survey equipment is fitted with a buoyancy tank which is of rigid material and with a fixed volume. A special coil is fitted around the tank, open at one end and linked to a pumping port with the other end. The pipe is connected to a reservoir, on board the ship, by a line and a pump. A movable piston in the coil separates the ballast fluid from the seawater. The system enables a rigid tank to be used, with the size of the coil selected to provide the required amount of buoyancy. The tank therefore has a long life.