Experiment on Countermeasure to Long Period Wave in Harbor

Long waves with periods of 1-5 minutes sometimes terminate the cargo handling and cause the break of mooring ropes in Japanese several ports. These long waves mainly consist of the setdown waves bounded in the grouping waves. Preventing such long waves from penetraing into harbors has great importance to keep the safe loading and un-loading. The present paper experimentally investigates the effects of breakwaters located at the port entrance for preventing long waves. The amplitudes of long waves can be reduced by the appropriate installation of breakwater without any amplification of harbor oscillation.