Effects of Certain Ship Motions on Cable Tensions in Systems for Handling Submerged Bodies

摘要

Certain conclusions are reached concerning the characteristics of towed bodies, especially ship-towed fish or sonar systems, with respect to weight and mass. The more important conclusions are: (1) The towline tension of any fish-ship combination will be zero when the downward magnitude of the acceleration of the towpoint at the ship is greater than the downward acceleration of the fish. This phenomenon can occur because the only forces available to accelerate the fish are its water weight and its vertical drag. (2) The zero tension point will occur while the fantail of the ship is moving up after it has passed its normal trim position. The towed body will continue to rise until it has reached zero velocity (at time t2), then fall until it is again captured by the towline (at time t3) which has continued its normal motion. The report gives equations describing the path of the towed body, and the consequences of the ultimate recapture of the body.