Estimation of damping from wave induced vibrations in ships

Paper in proceeding, 2017

Wave induced vibrations of container ships are high on the agenda in the industry. As a consequence of the MSC Napoli and MOL Comfort accidents, IACS has issued new unified requirements specifying functional requirements to include whipping in design of large container ships to reduce the risk of vessels breaking in two. Leading class societies like BV, DNV GL and LR have also class notations (WhiSp, WIV and FDA(SPR), respectively) for container ships to account for springing (and whipping) to reduce risk of fatigue cracks. Numerical analysis can be used, and an essential input parameter affecting the vibration level is damping. Due to the recent increase of container ship sizes, there is little relevant damping data available. Based on this, a study has been carried out to determine the damping for several container ships and other ship types. Several damping methods have been applied in order to reveal which method is more reliable. Results show significant differences in damping between ship types, but not all methods are regarded useful.