A crab fishing boat sank after two deckhands fell asleep while on watch, according to an accident report.

Crew members had to cling to a buoy before they were rescued by nearby vessels.

The Marine Accident Investigation Branch report into the incident has recommended that trawlers maintain a safe navigational watch and install alarms.

The accident took place shortly before 0430BST on 24 July last year near the entrance to Stornoway Harbour.

Local pub

According to the report, the crew of the Our Nicholas had discharged its catch into transport lorries at Uig on the Isle of Skye.

They then went to a local pub for about an hour before setting sail for Stornoway.

The crew had a meal on the way back to Stornoway, then the skipper and a third deckhand turned in to bed.

The watch was handed over to the two other deckhands after the vessel passed the Shiant Isles.

Deep water

They were instructed to call the skipper so that he could take the vessel into Stornoway Harbour.

However, he was awakened by a loud noise to find that the vessel had run aground on rocks.

The MAIB said both deckhands had fallen asleep and allowed the vessel to continue unmonitored.

The damage was so severe that the vessel sank when the skipper moved it into deep water.

After the crew abandoned the boat three of them clung to a buoy while a fourth was caught in rope after drifting away in the water.

Undetected leak

All four were rescued by two fishing boats which had witnessed the accident.

One man was detained in hospital after swallowing sea water.

The vessel's life raft did not inflate properly probably because of a previously undetected leak and a radio beacon was underpowered, according to the report.

The MAIB report recommends that owners keep a safe navigational watch on fishing vessels in the future and ensure emergency radio beacons are tested regularly.