For the present, we conclude that the engine failure was directly caused by low oil pressure. The lubricating oil level of the tanks was within set limits, but relatively low, when the vessel started to cross Hustadvika. The tanks were provided with level alarms, however these had not been triggered before entering Hustadvika. The heavy seas in Hustadvika probably caused movements in the tanks so large that the supply to the lubricating oil pumps stopped. This triggered an alarm indicating a low lubrication oil pressure, which in turn shortly thereafter caused an automatic shutdown of the engines.
The Norwegian Maritime Authority recommends that all companies take necessary precautions to ensure the supply of lubricating oil to engines and other critical systems in expected weather conditions. This should be done in accordance with the engine supplier and moreover, be included in the ship's risk assessments in the safety management system. The safety management system should also include procedures that tell what to do if a blackout occur, and it must be drill and training on such scenarios.
References to relevant legislation:
Regulations of 9 May 2014 No. 1191 on a safety management system for Norwegian ships and mobile offshore units, chapter 7 and 10 of the ISM Code.