The boat used by two missing fishermen feared to have drowned off Skerries in north County Dublin is believed to have capsized as they were lobster fishing.
Their boat was found upside down five miles south-east of Clogherhead yesterday morning and was towed in to port by the local lifeboat, but no bodies were recovered.
Using local knowledge, the search was concentrating on where the men, Ronan Brown, 25, from Skerries, and David Gilsenan, 35, from Rush, usually laid their lobster pots.
They were believed to have been working with 10 lobster pots off St Patrick's Island when the tragedy happened sometime on Friday.
As the local community, gardai, RNLI and Coast Guard rescue workers offered comfort and support to their distraught wives and families, a massive search operation continued from Clogherhead to Howth.
It involved volunteers manning RNLI lifeboats from Howth, Skerries and Clogherhead, around 30 local fishing and pleasure craft, at least four aircraft, an Irish Coast Guard S-61 helicopter from Waterford, an Air Corps Casa maritime patrol plane, an AW139 helicopter, and a garda EC-135 helicopter.
They were backed up by gardai, Coast Guard teams and local volunteers scouring the beaches and shoreline. Garda divers were also involved in a seabed search off St Patrick's Island.
"It's very sad. Hope is fading and I have talked to the families, who are in the lifeboat station and who are very upset," said Eugene Clonan, assistant director of the Irish Coast Guard service.
He said the men's boat may have capsized when they were fishing on Friday.
Counselling is also being offered to the families of the men.
Debris from the boat, as well as several items including a boot and an oilskin, were found by searchers. They said weather conditions were good with a fair sea state and good visibility.
One local woman said: "We're shocked and stunned. Please God they find them, one way or the other."
The search was launched around teatime on Friday when the men failed to return from a day's fishing. They had last been seen in their small 18-foot dory boat at around 11am on Friday morning.
As a major search began, families and friends began to gather in Skerries harbour as fears grew for the safety of the two young men.
Mr Brown married his wife Liz just six months ago, while Mr Gilsenan is also married with young children.
On Friday evening debris from the boat was found, giving rise to the worst fears of the 150 people who waited in vain for good news about the boat.
The debris was found halfway between the Rockabill lighthouse and St Patrick's Island off the Skerries shore.
One local fisherman described both men as "decent young lads, well known and respected".
He said Mr Brown was a deep-sea mechanic. "He has been fishing in Lough Shinny since he was a kid. David is also a life-long fisherman. They wouldn't have taken unnecessary risks.
"They are in-shore fishermen and wouldn't have been out too far, so something must have happened to the boat."
They were also involved with the local Skerries rugby club. "They were two local lads. They used to play rugby in Skerries. It's so sad for their families," a local man said.
Speculation rose that high winds and waves could have capsized the boat and thrown the men, who were wearing oilskins, into the water, which is extremely cold at this time of year.
The men, who normally fish off the islands in the bay, were last seen by a fellow fisherman at around 11am on Friday. The search was called off at 10pm on Friday and resumed at 7am yesterday, with still no trace of the two fishermen.
The widescale search was expected to begin again at first light this morning.