HALIFAX -- As officials with the coast guard and navy expanded the search for five missing Nova Scotia fishermen Tuesday, they also admitted the odds of finding them alive were rapidly falling with each passing hour.

Two coast guard vessels and three aircraft had already covered more than 18,000 square kilometres off Nova Scotia's southwest coast when the navy announced the search would shift eastward to account for currents and strong winds.

Navy spokesman Lt. Peter Ryan said the search, which started late Sunday, yielded few clues since the crew aboard a U.S. Coast Guard jet reported seeing a life-raft in the dark early Monday.

A U.S. Coast Guard spokesman said the crew of the twin-engine Falcon jet couldn't tell if there was anyone inside the raft, but they dropped a marker buoy nearby to track its drift.

Lt. Jared Carbajal, a spokesman for the U.S. Coast Guard's air station in Cape Cod, said the buoy, which mimics the drift pattern of a human body, was still transmitting data on Tuesday.

Ryan, a spokesman for the Joint Rescue Co-ordination Centre in Halifax, said the likelihood that the five young men survived beyond 24 hours was remote, even if they were all wearing immersion suits.

"That 24 hours is what we use as a survivability rate, as a general rule of thumb," Ryan said in an interview. "Of course, we're passed that now, but we're still searching. ... We're still hoping we can locate the crew and vessel."

The 13-metre fishing boat, named the Miss Ally, was on an extended trip to catch halibut when its emergency locator beacon transmitted a distress call via satellite shortly after 11 p.m. on Sunday.

The beacon, known as Emergency Position Indicating Radio Beacon or EPIRB, is typically activated when it hits salt water. The navy says there were no distress calls broadcast from the vessel's crew before the EPIRB went off.

The vessel capsized as it was thrown about by 10-metre waves whipped up by winds approaching hurricane strength.

Barry Smith, Maritime co-ordinator for the Canadian Coast Guard, said searchers were still picking up a weak signal from the EPIRB floating near the overturned vessel, which was found early in the search.

"We always try to go beyond that (24-hour time limit) to make sure we do everything we can to find them if there's a chance they're still alive," he told a news conference in Halifax.

Nova Scotia's fisheries minister, Sterling Belliveau, said he visited Tuesday with George Hopkins, a childhood friend whose 27-year-old son, Joel, is among the missing crew.

Belliveau is from Woods Harbour, the same village in southwestern Nova Scotia where most of the missing men are from. He said he knows all of them through hockey and other sports.

"They're all part of the fabric of our community," said Belliveau, who represents the area in the provincial legislature. "These are young men who work hard."

Like so many of his constituents in Shelburne County, Belliveau said he remained hopeful the fishermen -- all of them under the age of 35 -- were able to don survival suits and scramble into the life-raft.

Despite their ages, Belliveau said the men are experienced fishermen who understand the dangers of the sea.

Fishing, he said, is in their blood.

"We call them boys, but they're young men," said Belliveau, a former fisherman himself. "They're in the prime of their life. They understand the fisheries.

"Our community is praying and hoping that a miracle will happen."

Eddie Nickerson, warden of the Municipality of Barrington, said the focus of the community is on hearing news about the life-raft.

"I really think people around here have seen these kinds of events take place before and there has been survivors," he said.

"We all know the sea is ferocious and unforgiving, but as long as there's something to hang on to, there's always hope. ... We do realize that as time passes there's a chance you may not get the news that you want to receive."

Nickerson said people in Woods Harbour are rallying around the families of the five men. He said a local Baptist church was packed through Monday night for a prayer vigil.

The navy says the boat capsized about 120 kilometres southeast of Liverpool. The ocean temperature at the time was hovering between 2 C and 4 C, according to Environment Canada.

An offshore buoy -- about 160 kilometres from Shelburne -- recorded wind speeds at 92 km/h, and a weather station on Cape Sable Island registered southwest gusts at 124 km/h.

By Tuesday morning, wave heights had dropped to about six metres but the wind remained strong under clear skies.

A military Cormorant rescue helicopter, based in Greenwood, N.S., was joined Tuesday by a C-130 cargo plane from the same base. A small plane chartered by the Fisheries Department was also dispatched to the area.

Two coast guard vessels -- the light icebreakers Earl Grey and Sir William Alexander -- have been in the area since early Monday.

The Transportation Safety Board has sent investigators to Clark's Harbour, N.S., to assess what happened.