No-one will ever know what caused a trawler to sink off the Connemara coast in severe weather last September claiming the lives of four fishermen, a report said today.
Marine investigators said the tragic loss of the crew of the St Oliver on the tiny, uninhabited Duck Island remained shrouded in obscurity.
The report revealed the boat had fought its way through rough seas from Letterard, near Carna, before running aground on a reef. It said the vessel was so badly destroyed that the wreckage offered few clues as to what had happened.
The Marine Casualty Investigation Board (MCIB) said no comprehensive conclusions could be drawn, but that the men may have been caught unaware.
Four local men perished in the tragedy. Experienced skipper John Dirrane of Inishmor, well respected fisherman Michael Faherty, from Inverrin, Joseph Connolly of Carna, a businessman who was well-known locally as a master craftsman through his boat repair yard, and keen fisherman Michael Mullen, from Clifden.
The 30-year-old St Oliver had been in Mr Connolly's repair yard for over two weeks prior to the accident. The vessel departed Letterard on the 25 mile trip to Ros a Mhil shortly after 7pm.
The MCIB report revealed that two computers on the vessel had failed, the chart plotter and the radar or GPS system.
Investigators said it could have been caused by a short circuit, but could not explain why other equipment was not affected or why emergency battery power was not used.
They ruled out mechanical power failure or steering failure. The report said there was insufficient evidence of engine failure, or engine fire.
Locals recalled it had been a fine, sunny day with calm waters near the shore. But the weather deteriorated as the evening drew in and reports suggested high seas and a force seven or eight gale blowing.
Just over an hour into the voyage Mr Mullen sent a text message to a friend saying the seas were very rough and the boat's computers were down.
The MCIB said it was a significant piece of evidence as it suggested a problem on board. The report added it was the only indication of anything amiss and suggested the crew could not be certain where they were going.
At 9pm, 15 minutes since the last contact, the coastguard was alerted. A helicopter was dispatched from Shannon, the Aran Island lifeboat and the LE Ciara were sent to the area.
The wreckage of the St Oliver was found just after 11pm on the tiny uninhabited Duck Island. Three of the men's bodies were recovered over the next day. Mr Dirrane's body was not found for six days.
The MCIB said the tragedy reinforced the need for all seamen to prepare every voyage properly.