Fuel tanks of sunken Ilmarinen can be emptied in controlled way

The fuel tanks of the 80-year-old sunken defence ship Ilmarinen can be emptied in a controlled way before the oil leaking from the tanks poses a greater risk to the marine environment, according to an investigation conducted by the Finnish Environment Institute (SYKE)

The investigation of the wreck of coastal defence ship Ilmarinen continued in the northern Baltic Sea in the Finnish Exclusive Economic Zone from 12 to 19 August, said the SYKE in a press release on Tuesday.

The report said that the hull is riveted, and corrosion can affect the rivets in the seams and the steel sheets in different ways. The oil in Ilmarinen’s fuel tanks is a risk to the delicate and vulnerable Baltic Sea.

The objective of the expedition made to the Ilmarinen shipwreck was to determine whether authorities could extract the oil from the wreck and how.

The expedition was carried out in cooperation between authorities, including the SYKE, the Finnish Navy, and Border Guard.

Coastal defence ship Ilmarinen sank on 13 September 1941. The current estimate is that its tanks hold a total of 100,000 litres of light fuel oil.

The results of the expedition investigating the condition of the wreck and the location of the fuel tanks helped to shed light on how best to remove the fuel safely.

At the moment, the wreck is leaking a couple of drops per minute. The wreck is covered by a fairly thick layer of corrosion. One risk of the riveted hull is it splitting, which could result in a larger oil spill. This would be particularly disastrous for the nearby Archipelago National Park.

The current state of the wreck was examined with the help of a remotely operated vehicle (ROV) and divers.

“Corrosion was removed from the surface of the hull in a few spots, revealing an intact steel surface underneath,” said Tommi Kontto, Project manager of the SYKE.

When Ilmarinen struck a sea mine off the shore of Utö on 13 September 1941, 271 marines were killed in the accident.

The Ministry of the Environment is cooperating with other authorities to support emptying the fuel tanks of the Ilmarinen shipwreck as a joint authority effort.

The goal is to extract the oil from the sunken vessel in 2025–2026.

Earlier in February, Finland started an operation to remove oil from the coastal defense ship Ilmarinen, which sank 80 years ago.