漁具監視における漂流船位の予測例について

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While watching the fishing gear, it is important to know the relative position of a ship to the gear without recouse to any object (flag, light, reflector, radio buoy). From this point of view, the authors had experimented with the drifting of the Hokusei-maru, and reported that the direction and distance of drifting were estimated by the ship's head and wind velocity. And for the next study, it was found that a ship's head could be forecasted by parameters in regard to the direction of the wind and swell. And for the third study, we experimented on the accuracy of various predicted positions of a ship, in the North Pacific Ocean and the Okhotsk Sea. The experimental method 1. With the drifting velocity and direction already calculated by the following equations, some drifting positions are predicted before the ship starts drifting. U=(0.154+0.00024γ)W, β=150.°8-0.50γ where U: drifting velocity (knot), W: wind velocity (m/s), β: drifting direction, γ: angle between the direction of the wind and the swell. 2. Various positions of the ship could be determined by the bearings and distances of the corner reflector connected to the gill-net, after the ship opened drifting. 3. The determined and predicted positions of the ship were checked every 30 minutes. These observations were made for several hours every day for 22 days. The results 1. We say that the distance error is the length between the determined postion and the predicted position. The errors are shown in Fig.1, in relation to the daily drifting time. Furthermore standard deviations of distance errors are shown in Fig.2. 2. The daily distance made good errors in relation to the drifting time are shown in Fig.3. Furthermore, standard deviations of distance made good errors are shown in Fig.4. 3. Differences between predicted drifting directions and determined directions are shown in Fig.5 in relation with the drifting time. Standard deviations of direction errors are shown in Fig.6.
社団法人日本航海学会の論文
1976-08-20

漁具監視における漂流船位の予測例について

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