SCREAMS from a man who spent seven hours treading water in "treacherous" conditions without a life jacket, was just the start of a horrific marine accident.
The man, found by two sailors at 7am yesterday morning about five kilometres offshore, was on board a fishing trawler with six others when it overturned near Middle Island off Seventeen Seventy.
When the vessel capsized he was the only crewman above deck and was able to stay on the hull until about midnight when it sunk.
The man's discovery sparked an extensive search and rescue operation yesterday, which will continue today, in a desperate bid to find the six other people.
The crew - mainly from Cairns and believed to be involved in a sea cucumber fishing operation onboard the 17m vessel - were travelling north from Bundaberg, potentially to the Capricorn Bunker group.
The search and rescue operation spread throughout 100 nautical miles near Bustard Heads involved Federal Government vessels, Water Police, the 1770 LARC and several rescue helicopters.
But strong winds, seas with up to four metres of swell and heavy rain made seeing difficult.
RACQ Capricorn Helicopter Rescue Service rescue crewman Garth Snaidero said they found wetsuits, thongs and a bucket floating in the search area.
"It's probably one of the worst days on the job I've had weather wise," he said.
"It would be terrible (for the six missing men), my heart goes out to them today, if they were still out there or wherever they are.
"I really do hope we recover them ... We just want to find them as quickly as we can."
From the air the service deployed a self-located datum market buoy (SLDMB) at the search location to help Australian Maritime Safety Authority with tracking the tides and currents in the area.
The major search and rescue operation was headed from the Gladstone police station where the vessel's potential whereabouts was mapped in a search range of about 100 nautical miles.
Gladstone Water Police Sergeant Jeff Barnett said it was potentially the worst commercial vessel tragedy he had seen in 15 years.
Sgt Barnett said with deteriorating weather conditions expected overnight and today, the six remaining men needed to be found as soon as possible.
Without an emergency beacon activated from the vessel, Sgt Barnett said it was sheer luck the survivor - believed to have only suffered minor injuries - was found.
"It was just through sheer luck that a passing couple on a yacht managed to hear the screams of the individual who was rescued," he said.
"If it hadn't been for that we still wouldn't know."
Sgt Barnett said they had thrown "everything" at the search and rescue effort in what were treacherous conditions
"We're holding out a lot of hope," he said.
"We're still within the time of if they are in the water we hope to find them, however, given the conditions that (time) is rapidly deteriorating."
Gladstone Police Inspector Darren Somerville said the crewmen's next of kin were "understandably shocked".
He said the survivor had not seen any of the others since the boat capsized.
"At this stage we're conducting a search and rescue operation and we will continue to do so until there's no further hope of survival," he said.
1770 LARC! Tours owner Neil Mergard drove two police officers up the beach yesterday afternoon on his amphibious vessel, which has been used for 124 rescue missions.
"There's mountainous seas and very strong winds, the beach is coated in sea foam," he said. "We did collect some personal items, potentially from the vessel but as far as any sign of the vessel or more survivors, nothing at all."
The search was suspended late yesterday and will resume at first light today.
Update your news preferences and get the latest news delivered to your inbox.