Abstract: 13. A minesweeping system comprising a pair of floats, means for towing the loats of said pair in laterally spaced relationship, a hydrofoil shaped pressure plate, and suspension means for suspending said pressure plate from said pair of floats, said suspension means including shock absorber means for eliminating shock caused by wave action on said floats.

Abstract: 1. An acoustical source for minesweeping operations comprising a stator ing outer and inner surfaces which are surfaces of revolution and an open port connecting said outer and inner surfaces, an external rotor adapted to be rotated around said outer surface of said stator and having outer and inner surfaces which are surfaces of revolution with at least one open port of non-constant cross-section connecting said inner and outer surfaces, said port being substantially larger in cross-sectional area at said inner surface than its cross-sectional area at said outer surface and, said rotor having appreciably greater thickness between said inner and outer surfaces than said stator; and drive means for rotating said rotor at a predetermined speed.