On the Wind Effect on the Manoeuverability of a Bonito & Tunny Fishing Boat

Abstract

The manoeuverability of a tunny fishing boat under the strong wind was investigated for her three different conditions of trim, and the effects of the spanker and the bonito fishing platform on her manoeuverability were also studied separately. And the ranges of manoeuverabihity, or the limiting values of the direction and the velocity of the wind under which she can barely keep up her manoeuverability, were shown for these conditions. In the first half part of this report, there are given the results of a series of the wind-tunnel experiments with the image models of the above-water and the under-water portions of a tunny fishing boat carried out for the purpose of the above-mentioned investigation. And the distinctive features of the above-water portion of the fishing boat were made clear. In the latter half, the motion of the fishing boat under the strong wind with three different conditions of trim, or without aspanker, or with the bonito fishing platform, was solved using the experimental data obtained in the first half. In conclusion, the authors shew that the condition of even keel was the most fovourable for a fishing boat of this type to keep up her manoeuverability and safety, and that the excessive trim by the stern as well as by the bow was unfavourable, and they were convinaced quantitatively of the fact that the spanker played its part perfectly effectively under the oblique head wind and that the bonito fishing platform had almost no effect on the manoeuverability under the strong wind.