風圧による船舶の横偏流について-I(日本航海学会第31回講演会)

Abstract

The causes of ship's side-drifting are the force of wind on the upper structure of the ship, drift current increasing with the wind, rolling caused by wind wave and swell, and the ocean current and the tidal current. To search for the effect by wind action on the side-drifting, one of the above causes, it is necessary to make an experiment which is possible when removing the effects by the other causes. The authors planned to measure the side-drifting way with parameter V (speed of ship) when the ship's course took a right angle to the direction of the wind. The method 1. This experiment was carried out in Oshoro maru, a fishing training ship of Hokkaido University, when her speed was 3.5, 6, 9, 12kt, in the Bering Sea. 2. The Luneberg lens reflector (diameter 8 inch) which was connected to the salmon-gill net was selected as the datum point of experiment. In this case, the reflector was allowed to drift equally with the ship by current and wave, but felt no effect from the wind in spite of the movement of the ship. 3. As shown in Fig.1 the observers on the ship measured the distance and bearing of the reflector by radar at observation points 1 & 2, and calculated the side-drifting by those elements and the course and distance of the ship. The result 1. The relation between the wind velocity and side-drifting are expressed by equations (1)〜(4). 2. The relation between the proportional coefficient (K) in the equations (1)〜(4) and the ship's speed (V) is shown K=0.132e^<-0.143V>. 3. By 1, 2, they searched the relation between the side-drifting and the ship's speed and wind velocity, and got the experimental equation as follows U(kt)=0.132e^<-0.143V>W(m/sec). 4. The calculated value in the above-mentioned equation against any combination of wind velocity and ship's speed are indicated in Table 2. 5. The correction angle of the course is indicated in Table 3 when the ship's course took a right angle to the direction of the wind.