抄録
A cutter is a practical training-tool used to bring up the seamanship in fresh men. Its length is 9 meters long, and it can put up a mast for sailing. In addition, the transverse stability is enough for sailing on a windy day. On the other hand, the drawbacks of the cutter are that it will have a large angle of leeway on a closed hold sailing. It will take a long time sailing to run by the wind. The time restriction is a difficulty of the training during class. The purpose of this paper is to improve the sailing performance of the cutter. The authors have conducted several effective modifications of the original cutter design. Firstly, a center board was put on the keel at amidships. Secondly, the aspect ratio of a rudder was increased from 1.0 to 3.5 to improve the control forces. Lastly, in order to handle the sails easily by beginners, the main sail's area was decreased to about 80 percent of the original. The effects of these modifications were checked during the sea trials in Kagoshima Bay.
