Abstract
Recently, a special feature of the type of many trawlers turn into stern-trawler which supports towing tension of the trawl-net at the end of her stern. In the present paper, the author has analysed the motion of stern-trawler in steered condition under towing a net, especially about the effect of towing tension and propeller slip ratio on the manoeuvrability of ships. The analysis showed the following facts: By the effect of towing tension, directional stability of the trawler under towing a net increases and not only decrement of the yawing becomes rapid but yawing period changes in short.
