The outboard engine of a yacht that caught fire and sank off the coast of Cork was operating at the upper limits of its mechanical capacity, an investigation has found.
A report by the Marine Casualty Investigation Board said the continuous operation of the engine at its maximum design capacity was the likely cause of the loss of the yacht, Black Magic, on December 13, 2021.
The MCIB concluded that the outboard engine suffered a significant mechanical failure such that hot engine components were exposed to fuel and oil lubricants which spontaneously ignited and caused the fire.
The FC8 racing yacht, built in France in 1996, had departed earlier from Crosshaven, Co Cork, on a voyage to Kinsale Harbour to be laid up for the winter in a boatyard.
The report revealed the outboard engine caught fire about 75 minutes after leaving Crosshaven at about 11.50am, with the blaze spreading rapidly through the vessel.
The yacht’s owner and sole person on board was rescued by a fishing vessel about 10 minutes later after another fishing boat that had seen the burning yacht issued a Mayday alert to the Irish Coast Guard.
The RNLI lifeboat from Crosshaven, which had been deployed to the scene, reported the yacht sank in Ringabella Bay at 12.48pm.
The MCIB report said a yacht like Black Magic, which had a waterline length of 22ft, would typically require an outboard engine with a power capacity of at least 8 horsepower to achieve 4.2 knots — the speed calculated by its owner to reach the boatyard in Kinsale by 3pm that day.
It recorded the engine used on the yacht was either 3 or 4.2 horsepower.
The report said it could be reasonably deduced that the outboard engine was operating at maximum throttle power at the time in order to reach Kinsale by the appointed time.
It claimed any engine continuously operating at maximum power or beyond its design capacity would develop “significantly high temperatures".
The report said it was also “more than likely” there would have been some fuel spillage as the skipper had to refill the fuel tank in sea swells of up to 3m.
It claimed spilled fuel from the refuelling operation about 15 minutes before the fire was also very likely a contributory factor to the blaze.
The MCIB said another contributory factor was the lack of wind to assist the yacht’s passage to Kinsale.
The yacht’s owner and skipper, who had more than 30 years’ experience as a sailor, told investigators there had been “a flame-out of the engine and a bang”.
He said the fire immediately spread to spare drums of petrol fuel near the outboard engine, while he evacuated the cockpit onto the deck to escape the flames.
He said he was afraid to go into the cabin in case the fuel tanks would explode and trap him inside.
The sailor said he was contemplating jumping into the sea to escape the spreading flames and smoke but had resolved to delay entering the water for as long as possible.
The MCIB recommended that Transport Minister Eamon Ryan should update the code of practice for the operation of recreational craft to advise sailors to ensure auxiliary engines fitted to racing yachts had adequate power to allow safe passage when operating in adverse weather or sea conditions.
It also called on the minister to publish a marine notice to highlight the risk of refuelling or decanting volatile flammable liquids at sea in the vicinity of hot and exposed surfaces.