Studies on the shape of the Trawling net Field and Model experiments of trawl net

To obtain some effective suggestions as to the shape of the trawl net, authors conducted a series of field experiments and model experiments and on the six-pieces-net (Fig.1) used by Kagoshima-Maru (Table 1). Results obtained are summarized as follows. (1) The height of net-mouth was ascertained to be 5.0-4.0 m, provided that, warp length was 300-400 m, towing speed was 1.5-2.0 m/sec. The height of the net mouth was stationary especially at calm sea. (2) The empirial formulae between the height of net-mouth, H(m), and the towing speed, V(m/sec), was expressed in the following, H＝7.64V^{-1.18}. (3) At rough sea some extraordinary motions were observed on the height of the net-mouth and at the otter board: but the reason was unverified. (4) The experimental results of the model net with the scale of (1/21) were observed to be corresponding with the results of the field experiments