Large Slow Drift of a Ship in Slightly Modulated Beam Seas
The slow sway motion of a moored fore-and-aft symmetric ship in slightly modulated beam seas is discussed. The slow motion is associated with long waves. Depending on the speed of propagation, they may be decomposed into the locked, free and radiated long waves. Numerical examples are given for a Series 60 (CB= 0.6) ship in some different wave packets. Because of the restoring force developed by the mooring line, resonance may occur and the magnitude of the slow sway can be large. Real fluid effects are not included.
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