A Queensland police diver who found the first of six men missing after a fishing trawler capsized found a large air pocket in the hull next to two bodies but says it probably wouldn’t have saved the men.

Diving in the “blackest of black” water, Senior Constable James Hall had to rely on touch to explore the FV Dianne after it sank off the town of 1770 on 16 October 2017.

In the wheelhouse filled with floating mattresses, kitchen gear and rope, a foot behind a fridge was the first sign he’d located the crew.

“I could see a couple of toes. I told topside I could see a foot, so we knew we had one body in there,” Hall told an inquest in Gladstone on Wednesday.

The fridge had been wedged in the accommodation cabin’s only exit, potentially trapping the crew, the court heard.

Inside their bunkroom, Hall found a large air pocket but said it wouldn’t have helped the crew because the oxygen would have quickly been replaced by the crew’s exhaled CO2.

“In that case you go unconscious and drown in the water.”

Senior Constable James Hall at the Gladstone courthouse on Tuesday. The police diver had to rely on touch to explore the FV Dianne after it sank in October 2017. Photograph: Aaron Bunch/AAP

He found the body of Adam Hoffman, 30. The body of skipper Ben Leahy, 45, was located on a following dive. The bodies of Eli Tonks, 39, Adam Bidner, 33, Zach Feeney, 28, and Chris Sammut, 34, have never been found.

Hall said despite being “true watermen and athletes”, the crew would have been “incredibly” disoriented after the boat rolled upside down in darkness.

“Turn it upside down, flood that room and shake it all about and then have large objects moving around, your world is completely gone from what you know – you can’t see anything,” he said. “It’s like vertigo ... you don’t stand a chance.”

Small personal breathing devices in grab bags and emergency lighting near the exits would have given the crew a chance, he said.

Sole survivor Ruben McDornan also said lighting, grab bags and mini oxygen tanks in sleeping cabins would be a good recommendation to come from the inquest.

“That’s a small cost for what I believe to be an absolute must item,” he said.

Sole survivor Ruben McDornan arrives at the Gladstone courthouse on Tuesday. Photograph: Aaron Bunch/AAP

Counsel assisting the coroner, John Aberdeen, said the Dianne had all the correct safety gear but none of it worked when needed.

“Although there was an EPIRB on the rear wall of the wheelhouse, it could not be reached by anybody,” he said.

The vessel capsized in seconds and the crew had no time to put on life jackets or pick up grab bags, and an automatically deploying life raft failed to fire.

The inquest also explored whether ropes on the back deck could have coiled around the propeller causing the vessel to lose power in the large waves.

McDornan agreed it was possible but said it was more likely the ropes wrapped around the propeller after the boat capsized.