A Russian sailor downed two-thirds of a bottle of rum while at the helm of 7,000-tonne cargo ship – the Lysblink Seaways – and promptly passed out, running aground off the coast of Scotland, an investigation into the crash has found.

The 36-year-old chief officer was found to have imbibed half a litre of rum after taking a distressing personal call, before then passing out in his chair. The mammoth British-flagged cargo vessel then slammed into rocks off Kilchoan in Ardnamurchan. No one was harmed in the incident but 25 tonnes of marine gas oil were spilt into the sea as a result of the accident.

An investigation by the Marine Accidents Investigation Branch probe has revealed a series of procedural failings aboard the Lysblink Seaways that led to the ship being grounded off the west coast of Scotland, STV reported.

The chief officer took over from the second officer despite being drunk. At 2am the ship's course was not adjusted despite a prompt from an on-board alarm and at 2.40am the chief engineer reported the ship had run aground, with a breech in a double-bottom sludge tank in the engine room.

The Russian first officer was found to be eight times above the 0.35mg/l limit when he was breathalysed. The master and second officer were found to have a zero reading.

Safety failings were also found after it emerged the no one was keeping watch on the bridge. The master claimed he was "keeping his watch in the deck office". Lysblink Seaways was scrapped two weeks after the accident.