漁場における漂流船位の推定例について

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An officer on duty on a fishing vessel watches the fishing gear drifting after setting a salmon gillnet or a tuna longline. At any time, if he can estimate his ship's position by any method concerning the gear without recourse to any object (flag, light, reflector, radio buoy), he can employ this method to watch the gear effectively. The authors experimented with the drifting of the Oshoro-Maru, a fishing training ship of Hokkaido University, and reported that the direction and distance of drifting could be estimated by the ship's head, condition and wind velocity. In our next study, accuracy of the estimated ship's positions was experienced according to this method, in the Bering Sea. The experiment 1. The drifting velocity and the direction having been calculated by previously reported equations [1], some drifting positions were estimated. 2. The ship's positions can be determined by the bearings and distances of the corner reflector connected to the gill-net. 3. The determined and estimated ship's positions checked every 30 minutes are shown in Fig.1. The accuracies of estimated positions 1. The daily distance errors (error of distance made good) related to the drifting time are shown in Fig.5. Furthermore standard deviations of distance errors are shown in Fig.6. 2. The differences of estimated drifting directions from the drifting direction in relation with the drifting time are shown in Fig.7. Standard deviations of direction errors are shown in Fig.8. 3. Under an ordinary condition a drifting time is 6 to 8 hours, the distance error is within 0.5n.m. (s.d.), and the direction error is about 5°(s.d.). According to this method, we could obtain satisfactory results from various angles for the sake of keeping watch over the fishing gear.
社団法人日本航海学会の論文
1973-07-30

漁場における漂流船位の推定例について

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