Low oil pressure has emerged as the likely cause behind an engine failure on Viking Ocean Cruises’ 2017 built Viking Sky on Saturday off the coast of Norway, Sjofartsdirektoratet (the Norwegian Maritime Authority - NMA) said in a statement.

“For the present, our conclusion is that the engine failure was directly caused by low oil pressure. The level of lubricating oil in the tanks was within set limits, however relatively low, when the vessel started to cross Hustadvika,” NMA said.

“The tanks were provided with level alarms, however these had not been triggered at this time. 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 level of lubrication oil, which in turn shortly thereafter caused an automatic shutdown of the engines,” NMA said.

The NMA said it has drawn up a general safety notice about ensuring a continuous supply of lubricating oil to engines and other critical systems in poor weather conditions. “This should be done in cooperation with the engine supplier and, moreover, be included in the ship’s risk assessments in the safety management system,” it noted.

Viking Ocean Cruises said in the same statement: “We welcome the prompt and efficient investigation carried out by the NMA and we fully understand and acknowledge their findings. We have inspected the levels on all our sister ships and are now revising our procedures to ensure that this issue could not be repeated. We will continue to work with our partners and the regulatory bodies in supporting them with the ongoing investigations.”

NMA said it is in a continuous dialogue with the company and classification society, and this cooperation has been successful. “We will follow up the ongoing work to rectify damages on vessels. Furthermore, we will continue the constructive dialogue with the classification society, company and the Accident Investigation Board Norway in order to reveal underlying causes and identify appropriate measures,” it said.

The 47,842 gross ton Viking Sky is under technical management of Wilhelmsen Ship Management, which is part of Wilh. Wilhelmsen Holding ASA group in Norway, the last named company says on its website.