Abstract
The study concerning a ship's speed affected by wind and waves has so far been done by statistical means from the records of ship's log book, etc, by most scientists. In this paper, the authors have made experiments aboard the habitual vessel. They embarked in the training ship Oshoro-Maru of Hokkaido University on the Bering Sea cruise from June 29 to August 11, 1969. Speed and fuel consumption were measured when sailing 12 different courses of which the angles between the ship's fore and aft lines and the wind direction were chosen to be a common multiple of 30°. Figs.2〜9 show the relations between speed and wind direction, speed and fuel consumption, as computed by the least squares method on the cosine curve a cos(α+β)+b (a, b: coefficients, α: wind direction angle, β: phase angle) ; the results approximate well to the measure values, as shown in the equations V_1〜V_8, F_1, F_2, F_4, F_7 and F_8. The curves of speed and fuel consumption against the wind direction lie asymmetrically respectively when the wind direction angle is 0°. Coefficient a is estimated to be proportional to the wind force, see Fig.10. The relation between speed and fuel consumption represents an ellipse in shape as is shown in Fig.11.
