Abstract
This paper proposes an approximate estimating method for the amount of shipping water over bulwark with freeing port. The approximate method is based upon concepts of weir and of orifice on hydraulics. A series of numerical examples are presented for a two-dimensional model of trawler by using the proposed method. And experiments are carried out for any conditions to examine the properties. Consequently, the following conclusions are given, i) good agreement is obtained between numerical results and measured experimental results. ii) a large amount of shipping water get into upper deck through freeing port even if wave elevation is not higher than the top of bulwark. iii) in the case of constant opening ratio, the amount of shipping water through comb-type freeing port is smallest among some types of freeing port.
