The families of two French fishermen who died when their trawler sank in mysterious circumstances off the English coast 17 years ago said on Monday they were experienced sailors and would never have compromised safety on board.

Yves Gloaguen and Pascal Le Floch, whose bodies were recovered by UK search and rescue teams, were among five crew who died when the Bugaled Breizh sank on January 15, 2004.

A coroner's inquest in London is looking into the tragedy and their families' claims that a British or US submarine may have become caught in the ship's nets and dragged it down.

Le Floch, 49, came from a family of fishermen and was described as someone who had the sea "in his blood since he was small", his family told the High Court.

"As a boy, he would go to sea during the school holidays... we would never have imagined such a brutal, even violent death," they added.

Le Gloaguen, 44, was said to have been "jolly" and a "joker" but "serious when he went to sea", his sister said.

"He would have never taken risks to put his men and his ship in danger," she added.

Thierry Lemetayer said his father Georges, 60, who also perished in the sinking, began working on trawlers at the age of 13 and was the family's only breadwinner.

He remembered his father talking in a matter-of-fact way about a spate of accidents between fishing boats and submarines, expressing hope the problems could be solved.

"It hasn't obviously changed quickly enough," he added.

The Bugaled Breizh -- "Children of Brittany" in the local Breton language -- was based in Loctudy, in the Finistere region of northwest France.

It went down off the coast of Cornwall in southwest England in less than a minute in relatively good weather.

Yves Gloaguen and Le Floch's bodies were recovered by UK authorities while that of another crew member, Patrick Gloaguen was found in the wreck during salvage operations.

Lemetayer and Eric Guillamet's bodies have never been found.

French courts spent years investigating the sinking, which took place near where NATO and Royal Navy exercises were being held, but the probe was inconclusive.

Speaking before the hearing, Thierry Lemetayer told reporters: "If the British Ministry of Defence or NATO says, 'we did cover up things, we apologise and we'll sort it out', I'll go home, I won't bother anyone and you'll never hear from me again."

Lawyer Dominique Tricaud, who represents Lemetayer's family, told AFP the proceedings "give us very great hope".

"The families think that the (British submarine) HMS Turbulent was responsible for the sinking and are waiting for the trial to prove it," he added, referring to the inquest.

"They're not out for revenge but can't grieve on a state lie."

The former commander of HMS Turbulent, Captain Andrew Coles, will give evidence on October 12 about the vessel's location on the day the Bugaled Breizh went down.

A senior officer from the Dutch navy's Dolfijn submarine, which is known to have been in the area at the time as part of a NATO training exercise, will also give evidence.

Britain's Ministry of Defence and the Royal Navy have both denied claims that one of its submarines was involved in the sinking.

In 2006, the French Marine Accident Bureau concluded that the sinking was an accident, most likely caused by one of the boat's trawler net cables snagging on the seafloor.

Other scenarios, such as a collision with a freighter, have been ruled out.

The inquest into Yves Gloaguen and Pascal Le Floch's deaths began in Cornwall in 2020 but was adjourned due to Covid-19 restrictions and transferred to London.

Judge Nigel Lickley told the fishermen's families in March he would "carry out a full, rigorous and fair investigation".

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