Heel angles in turn andd passenger safety

AuthorsFerrari, V., Boom vd H., Kisjes, H.S., Quadvlieg, F.H.H.A.
Conference/JournalSustainable and Safe Passenger Ships
DateMar 4, 2020
Sharp turns of passenger vessels may cause high heel angles, which may lead to dangerous situations on board. Passengers and crew could suffer injuries and any unleashed cargo could start shifting, further compromising the stability of the ship. For this reason the International Code on Intact Stability (ISC), adopted by the International Maritime Organisation (IMO) in December 2008 with resolution MSC.267(85), contains one rule specifically for passenger vessels. It presents a formula with the purpose to estimate the heeling moment due to turning and to verify that this calculated value does not exceed a certain criterion.

The restriction on maximum heel angles is relevant for both passenger safety and to avoid shifting of cargo. It is noted that “weather dependent lashing” has been adopted by many ship owners. However sudden turning of a vessel can occur even in good weather conditions, e.g. for change of course, avoiding collisions, grounding or due to failures in the autopilot or steering gear. In 2018 MARIN investigated the cause of the flooding and sinking of the Korean ferry M/V Sewol, who heeled excessively and capsized while sailing in calm water. The results of the investigation inspired additional research into the heeling during turning for ferries.

This research showed that the present ISC formula underestimates the heel angles when compared to both the maximum and steady heel measured during model tests. Therefore there is a clear need for a revision of the ISC requirement.

This paper presents the results of this research on heeling in turn and discusses their implications with respect to the ISC rule. A revised methodology for evaluating the heel angles in turn is then proposed in order to overcome the limitations of the present ISC formulation. Finally conclusions are drawn in the last section.
stability, seakeeping and ocean engineeringrenewablesoil and gasinfrastructuremarine systemslife at seamonitoringtrials and monitoring