Evaluation of a conventional otter board used in trawl fishery in Ise-wan Bay and proposal of a new design

Abstract

To improve the otter board used with a semi-pelagic trawl net, we evaluated the conventional otter board used in Ise-wan Bay and compared the lift and drag characteristics with the following experimental otter board. The experimental otter board was designed to enable both semi-pelagic and bottom trawl operations along with a high lift-drag ratio. Results of model experiments indicated that the drag coefficient of the experimental otter board was smaller, and the lift-drag ratio of the experimental otter board was 1.41 times higher than those of the conventional otter board respectively at intended attack angles. In an experimental operation using a semi-pelagic trawl net, the otter board distance was 1.1-1.2 times wider than that of the conventional otter board.