船速に及ぼす風浪の影響について-IV(日本航海学会第29回講演会)

抄録

The effect of winds and waves upon any one ship's speed seems to be different from that upon any other owing to type, size, condition, ability, etc., of a ship ; the author has some interest in the problem whether or not the speed reduction of a ship in ocean has a same tendency as that in a specific sea. In this paper, he has attempted, for an example of it in the specific sea, to analyze the navigatonal records of the connecting steamer "Yotei-maru" (passenger boat) in Tsugaru Straits. 1. As shown in Fig.1, all data are separated into 7 sections according to the direction of the winds. 2. The relation between the elapsed after leaving the dock and the slip is shown in Fig.2. 3. As the revolutions of the main engine are changed according to the circumstances he converted those speed reductions into the reductions when they are fixed in 190 RPM. 4. The mean speed reductions of the ship, weights of data, are shown in Table 1 against each section and wind wave grades. 5. Let the speed reduction be expressed by equation (△)=aD+bD^2 with parameter D, and a smooth curve is drawn along the points plotted from data, the speed reduction due to wind wave grade is shown by forms (1)〜(7) in each section in Fig.3. 6. When the values calculated by forms (1)〜(7) are plotted and the smooth curve is drawn along the plotted points, the speed reduction due to the wind direction is obtained as forms (8)-(11) ; Fig.4 shown them. 7. The relation between wind wave grade and wind velocity in the strait (1962) is shown in Fig.6, and the relation between wind velocity and wave height is shown in Fig.7. 8. The mean fetches in the strait corresponding to each direction of wind are shown in Fig.8, and calculated wave height by S-M-B method are shown in Fig.9.