Abstract
Long period waves with periods of 1-5 minutes sometimes terminate the cargo handling and cause the break of mooring ropes in Japanese several major ports. Such damages sometimes occur in Kasima-port located at the central part of Japanese main island A series of field observation for long period wave height was carried out in the port employing several wave gages. The observation results demonstrate that long period waves induce the large surging motion by resonance between the wave agitation and a mooring system consisting of vessel and elastic mooring ropes.The variation of bounded wave components included in the long period waves is also investigated in the paper.
