The variation of the working speed of the Danish seiner was large among the hauls yielding the same amount of catch from the same depth zone under the same grade of wind wave. In the present report, accordingly, the relation of working speed to the power of main engine of the boats was examined because of the following reasons: The records were collected from the 22 boats ranging 220 to 340 Hp in the main engine. It is probable that the working speed depends on the propulsive power and the pulling and hauling ability of the boats. They depend chiefly on the power of main engine. And the results obtained are summarized as follows:
1. The time expended to complete a haul and the laying time had no relation to the power of engine.
2. The sinking-pulling time decreased but the hauling-brailing time increased with the power of the engine at a rate of 1.1 min. per 100 Hp.
3. It was hard to find the relation of the length of the interval between succeeding hauls to the power.