Low drag subsurface buoy with integral acoustic Doppler current profiler

Describes investigations by Flotation Technologies and Mooring Systems Inc. to develop a low drag subsurface mooring apex buoy that contains an RD Instruments acoustic Doppler current profiler current meter. Five different candidate mooring apex buoy systems are compared with regard to their drag, inclination and stability in current and effect on the performance of a typical mooring. The drag coefficients of cylindrical and spherical buoy candidates are Reynolds number sensitive in the velocity range of 1 to 3 knots. This leads to calculated and observed hydrodynamic instability due to minute variations in current velocity. An airship shaped streamlined body was found to have the lowest drag, best inclination response and little or no Reynolds number sensitivity in the current regime of interest.