The investigation into the loss of the fishing boat Rising Sun off Co Wexford on Tuesday is expected to concentrate on why the vessel sank so quickly.
This appears to have prevented the three crew members on board from sending out a Mayday signal.
Two of the three fishermen were picked up from the water on Tuesday night, but one of them died later. The third man is still missing.
Jimmy Meyler of Slade, Co Wexford, and Ian Tierney of Kilmore Quay were brought ashore after spending several hours in the water. They were taken to Wexford General Hospital where Mr Meyler was later pronounced dead.
The search for the skipper of the Rising Sun, Patrick Colfer of Ballyhack, Co Wexford, is to resume this morning after the LE Orla and local lifeboats spent yesterday patrolling an area about two miles southeast of the Saltee Islands.
The Rising Sun, a lobster boat fishing out of Kilmore Quay, was last seen by another boat at about 3pm on Tuesday.
Naval Service personnel aboard the Kilmore Quay lifeboat used special side-scanning sonar equipment to view the seabed at a depth of 158ft, after the fishing vessel Golden Rule spotted oil on the surface of the water early yesterday.
However, as the weather deteriorated yesterday afternoon lifeboat personnel said there was little to be gained by continuing the search through the night.
Two investigations into the tragedy - a Garda inquiry and an investigation by the Marine Casualty Investigation Board (MCIB) - are under way. Gardaí and an MCIB investigator were last night waiting to speak to Mr Tierney about the accident. He was expected to be discharged from hospital after being treated for hypothermia.
Mr Colfer's brother, Eamon, and about 20 local lobstermen waited anxiously in Kilmore Quay for news, but as darkness fell the lifeboat service said the search would be stood down until this morning.
In the Kilmore Quay lifeboat station, and on the quayside, the conversation centred on the number of hours the men spent in the water before the alarm was raised.
The Irish Marine Emergency Services said it received no Mayday signal from the boat.
The Department of the Marine said there appeared to have been difficulties picking up an automated distress signal which is activated when an apparatus comes into contact with water.
A spokesman said a signal from an automatic system was picked up at Kinloss, in Scotland, at 2.30pm. However, the department spokesman said two possible positions were given. "One of these was in Co Monaghan and one was at 50 degrees north and 17 degrees west, which is very much west of Wexford." The spokesman added that the timing of the signal would also contradict the last sighting of the vessel, which was said to be at 3pm. Because of this the department said it may have been a phantom signal and not from the stricken trawler. Rescue services were not notified until some time after the boat failed to return to Kilmore Quay at 4.30pm on Tuesday. By the time they were picked up, the two men had been in the water for several hours. Both were wearing life-jackets.
While mechanical failure has not been ruled out, lobstermen and Kilmore Quay lifeboat station officer Seán Radford said the Rising Sun's engine had been refitted earlier this year. This had automatically led to a safety inspection by the Department of the Marine, and the boat had been certified seaworthy.