Abstract
This paper deals with the development of a new model fish aggregation device which prevents trawlnet entanglement. Labolatory experiments were carried out to measure hydrodynamic forces acting on a submerged hemisphere in a flow and under regular waves. The obtained results are summarized as follows; The drag and lift coefficients in a flow are constant. The measured longitudinal wave force is decomposed into the drag and the inertia forces by means of the Morison equation. As K. C. number increases, the longitudinal maximum wave force decreases almost proportionally. The vertical maximum wave force varies from 2 to 10 times of the longitudinal maximum wave force. The longitudinal drag and inertia coefficients under regular waves are given as a function of K. C. number, h/D and h/gT2.
