Characteristics of a deep sea neutrally buoyant float

A free, acoustically tracked, neutrally buoyant float, with an open loop buoyancy control system actuated by command from the surface, has been developed as a dye pool tag for deep ocean diffusion experiments. An internal battery powered motor driven pump varies buoyancy by metering hydraulic fluid into or out of an external chamber separated from sea water by a flexible diaphragm. The vertical transient movement of the float submerged in a motionless ocean has been analyzed using normalized dimensionless parameters. This simple analysis does not strictly apply in highly stratified water where there is substantial interaction between the float and the surrounding fluid; however, the analysis can be used for the initial design of neutrally buoyant floats. A float at equilibrium depth, being less compressible than water, will not necessarily duplicate periodic vertical motions of the water mass in which it is embedded.