On The Steady Turning of Towed Ships System

We have discussed the course stability of towed ships system in the Journal of the Society of Naval Architects of West Japan No. 42, 43, 44 and 46. In this paper, the auther theoretically and experimentally deals with the steady turning of the towed ships system in still water by the parameters-a ship's course stability criterion, towing points, length of towing rope, number of ships, rudder angle and rudder area ratio of the tugboat, and size of ships. The results are as follows :(1) During the region of short towing rope, the last towed ship has a larger radius than the tugboat, then by the increase of the towing rope's length, the last towed ship gradually tends to turn with the smaller circle and eventually when the towed rope length is over the critical rope's length qcun, the system falls into irregullar motion, and this is identified, and qualitatively agrees with the experimental results.(2) The steady turning of the system by steered the rudder of the tugboat is only possible when the towing rope's length is under qcun L and which is given by the equation (6).(3) The larger the rudder angle and the rudder area ratio of the tugboat are the smaller the radius of steady turning of the towed ships system are.(4) If the rudder angle and rudder area ratio of the tugboat are constant, a) the radius of steady turning decreases, when the number of towed ship increases, b) the radius of steady turning becomes larger, when the towing rope's length increases, and the fore and aft-towing points are apart from the centre of gravity of the towed ship, except the last towed ship.