Experimental Analysis on the Anchor Mooring Force in Heavy Storm Condition

Abstract

When a ship is anchoring in a stormy weather ， the anchor often comes off due to the extreme overload ofthe mooring force ． Then ， the ship begins to run and sometimes causes aground ， and this makes a serious disaster ． The accident of l' Toya − maru ， ' was also one of them ， There are stHI such accidents and bst many crew in these days． However ， the mechanism of anchor mooring f (〕rce in a stormy weather ls complicated and not clear ． Although the wind fbrce to the superstructure becomes the m 司 or anchor mooring fbrce ， it may not be enough even ifthe wave driftlng fbrce is considered ． In this paper， the accident of the sail training ship " Kaiwo Maru " that was caused under t 】 1e stormy weather by the large − scale typhoon off Hushiki − Toyama harbor in 2004 is investigated based on the model tests． Then ， it is fbund that the peak mooring fbrce becomes extremely larger even in the ahead condltion again5t wind and wave when the ship is more strongly pulled by the wind fbrce and wave drifting fbrce ． This may causes the some kind of deadlock condition that the windlass can not pull up the anchor but the anchor begins to walk ，