Police say they have found the commercial fishing trawler Dianne in which six men are believed to have drowned when it sank in heavy seas on Monday night.

The sea cucumber fishing boat was detected by sonar about two to three nautical miles off Round Hill Headland, near Seventeen Seventy.

Police confirmed the discovery in a statement released just after 6:00pm on Friday.

Water Police remained at the scene overnight and a full recovery operation was due to commence this morning.

Seven crew were aboard the boat when it capsized.

Ruben McDornan was the only person rescued, after he clung to the overturned hull for several hours.

After days of searching for the other crewmen, police conceded yesterday the search for skipper Ben Leahy, Adam Bidner, Adam Hoffman, Zach Feeney, Chris Sammut and Eli Tonks had become a recovery mission.

Ben Leahy, Eli Tonks, Adam Bidner, and Adam Hoffman are among the missing fishermen. ( ABC News )

Zach Feeney, 28, was one of the six men on board. ( Facebook: Zachary Feeney )

Chris Sammut, 34, worked in film production on the Gold Coast. ( Facebook: Chris Sammut )

Bad weather and rough seas hampered the search effort.

Family members of the missing men had joined the search with two chartered boats, one relative in a plane and others combing the beaches for any signs of their loved ones.

Earlier, Gladstone Inspector Darren Somerville said it had been very tough for the families.

"They're all upset. Most of them it's hit home it's not going to be an ideal outcome," he said.

Twelve boats were involved in Friday's operation, along with a helicopter and several vehicles that patrolled the shoreline.

At least one of the boats was fitted with side scan sonar, using soundwaves to detect any possible man-made items under the water.

Mr McDornan, the sole survivor of the accident, was "very, very lucky" to be found, according to his rescuer.

Mal Priday was sailing with his wife and brother-in-law when they come across Mr McDornan on Tuesday morning while on their way to Pancake Creek.

Mr Priday said Mr McDornan, who did not have a life jacket, was found wearing only a pair of shorts about 20 nautical miles from where the boat was thought to have sunk.

Ruben McDornan was clinging to the trawler's upturned hull before it sank. ( Facebook: Ruben McDornan )

"The right time, the right course, the right speed… the odds are just incalculable," he said.

Earlier Mr McDornan's wife issued a heartfelt thank you for the "messages, thoughts and prayers" following her husband's rescue.

Sammy McDornan was reunited with her husband Ruben in Gladstone yesterday after he was saved from the hull of the trawler

In a Facebook post, Mrs McDornan said her husband was "doing OK" despite his ordeal.