Dynamic response of an ocean construction barge to various sea states

Abstract

load handling technology in the sea environment to place heavy and bulky loads accurately on the ocean floor is in its preliminary stages of development. The load handling system is usually mounted on a platform which interacts with the sea surface, imparting dynamic loads to the lifting lines that are not experienced on land. This study evaluates the response of a specific load handling system composed of a crane and constant-tension winch mounted on AMMI pontoon barge to sea states 3, 4, and 5. The motions of heave, pitch and roll were coupled by phasing at specific load suspension points and the rms values of the vertical displacement and acceleration at these points were calculated using spectral analysis techniques. It was found that the constant tension winch could compensate for the motions of sea state 3 but that the probability of exceeding the winch capability at sea state 4 was large enough to limit operations to missions of very short duration.