Author(s)

L.K. Kobylinski

Abstract

Present manoeuvrability standards as set up by IMO do not include criteria for directional stability of ships. However, most ships with high block coefficient are inherently dynamically unstable. Ships having moderate or small amount of directional instability could be handled quite safely, but ships having large amount of directional instability are difficult to handle and may pose danger to sea traffic. The paper presents results of the study of the possibility of safe handling of directionally unstable ships. A number of pilots were asked to manoeuvre directionally unstable models with different amount of instability and an attempt was made to establish allowable limit of directional instability of ships on the basis of the analysis of these tests. The results were compared with the similar study performed in Japan. 1

Keywords