Abstract: An auxiliary gas source for blowing a ballast tank of a submarine craft includes a casing with a store for pressure gas, a container for liquid and a gas generator proper into which the liquid can be forced by the gas. The liquid is contained in a flexible bag and the pressure gas acts on the bag from the outside, to be separately discharged as a supplemental supply of gas.

Abstract: The invention relates to a self-propelled shark-proof cage which is provided with at least one access opening and a propeller mounting frame having pivot means coupling it to the cage so that the propeller mounting frame is pivotal about two axes at right angles to each other, and the propeller mounting frame carries on it an air motor and a propeller. The frame is provided with buoyancy means so that it can be made to be of approximately the same gravity as sea-water, and the air motor is driven by compressed air so that the cage can be propelled through the water, thereby enabling abalone divers to collect abalone without fear of predators and, beacause of less exertion, for longer periods of time.

Abstract: Apparatus for submerging a floatation body for placement beneath a floating structure is comprised of a tank which is divided into at least two sealed compartments. The tank has a total gross weight which is greater than the buoyancy force of the floatation body and yet has a volume which will allow it to float when filled with air. In order to tailor the gross weight of the tank for use with floatation bodies having a range of buoyancies, weights are removably attachable to the tank. Fluid passageways are provided in the bottom of each compartment, and an air outlet, containing a control valve, is located near the top of each compartment to permit selective flooding of the compartment to submerge the tank. Air inlets entering the top of each compartment are provided with control valves to allow selectively refilling the respective compartments from a remote air generating system.

Abstract: A watertight vertically elongated rigid shell or hull of a size small enough to be transportable over highways has a detachable snorkle extending from its top and contains a power source which may be used to drive pumps within the device and/or to drive mechanical devices, such as rotating blades, winches, belts, drills or propellers, which are located externally of the hull. The hull of the device is divided into upper and lower compartments, of which the lower compartment can be completely or partially flooded with water which acts as a ballast helping to stabilize the device and controlling submersion thereof and its submerged position.