201703 Hydrodynamic interactions while berthing

 

In daylight conditions and good visibility a passenger ship had turned on arrival in port and was making fast port side to berth. The vessel was in position with single springs fast fore and aft and was proceeding with head, stern and breast lines.

Another passenger vessel was passing between the berthing passenger vessel and a small bulker moored on the quay across the channel. It was estimated that the underway passenger vessel passed the berthing vessel at a lateral distance of approximately 30 metres. The maximum speed of the underway vessel while passing was 6.7kt.

An officer on the berthing vessel was standing by to receive a shoreside gangway connection when he noticed the vessel starting to surge ahead and reported this to the bridge. The bosun on forward station simultaneously reported the forward spring coming under heavy strain.

 

Lessons learned
- The surge was most likely due to the hydrodynamic interaction caused by the underway passenger vessel passing at a very close lateral distance of 30 metres at a speed of more than 6kt.
- The relatively narrow channel probably magnified interaction effects.
- The surging of the moored vessel could have caused the spring line to part, which in turn could have caused serious personal injury or even death.
- The officer posted on the bridge wing of the berthing vessel did not report the close approach of the underway passenger vessel sufficiently promptly. Had the officer done so, the bridge team might have been able to warn mooring station leaders to take extra caution and stand clear.
- The entire bridge team must maintain situational awareness throughout the mooring process, and not relax and reduce alertness once vessel is in position with spring lines fast.