On the Stopping Distances of Giant Vessels

Abstract

This paper considers a practical solution to the stopping distance of ships, with particular reference to modern giant tankers. One solution to the problem has already been evolved by Captain H. Topley of the Honourable Company of Master Mariners. The present paper tackles the same subject from quite a different viewpoint. The basic assumptions on which the mathematical treatment has been based is presented in Section 1, which also includes the calculation formulae of the speed and distance run at any time in a manœuvre, without proofs. Section 2 deals with clarifying the essential differences between Captain Topley's theory and the author's. The validity of the theories is examined in Section 3 by comparison with the results of actual ship tests. Section 4 presents calculation diagrams prepared by the author. The only reliable data available by means of which captains can predict the stopping behaviour of their ships after ordering STOP ENGINES are the results of inertia tests conducted at the sea trials when the ships were built. The inertia tests, however, are usually performed for only one case in which the approach speed is assigned to HALF AHEAD or the so-called manœuvring full ahead speed. Therefore most masters are glad of any knowledge of how to predict the movements of ships from any reduced speed.