A team of US researchers believe they have narrowed down the search for the wreck of Captain Cook's HMS Endeavour to a group of five ships in a Rhode Island harbour, but it is unclear if any artefacts would ever make their way to Australia.

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The remains of the ship the British explorer used for his voyage to Australia, supposedly uncovered in Newport Harbour, legally belong to the state of Rhode Island.

US archaeologists from the Rhode Island Marine Archaeology Project (RIMAP) will work with the Australian National Maritime Museum in Sydney to confirm the remains of a ship found in the harbour belong to the HMS Endeavour.

They knew Endeavour was likely to be one of 13 ships scuttled in 1778 by the British navy in order to blockade a channel during the American Revolution.

The research team, headed by marine archaeologist Kathy Abbass, uncovered new documents from the UK which allowed them to narrow down the location of the Endeavour in a 500-by-500-metre area.

The marine archaeologists believe five ships are in that section of the harbour. The team has already mapped four of the wreck sites.

Sorry, this video has expired Captain Cook's Endeavour found off Rhode Island?

"We have one more year to do of this kind of preliminary work," Dr Abbass said.

"But to figure out which ones are which means we have got to do excavation."

Australian National Maritime Museum maritime archaeologist Kieran Hosty said experts dived the area in September after using a site scan sonar, but the water was extremely murky.

He predicted 10 to 15 per cent of the hull remained.

"We won't see a ship with sails and masts up, but 10-15 per cent of the hull — hopefully," Mr Hosty said.

Even if the researchers do find items from Captain Cook's historic ship — and they are proven to be authentic — Australians may have to travel a long way to see them.

"The legal aspect is the ship belongs to America under their legislation," Mr Hosty said.

"The ship was abandoned by the British, the insurance money paid out and the State of Rhode Island has claimed ownership of the vessel.

"With the Endeavour, we may have to enter into the memorandum of understanding to allow the material to be lent to us.

"There is a weird duality with Endeavour in Australia — on one hand we have a ship of exploration for many people in Australia — for other people in Australia it is the ship of occupation, that led to the European occupation in Australia."

240 years under water takes its toll on Endeavour wreck

Built as a coal transport ship in 1764, HMS Endeavour carried Captain Cook on his historic voyage to Australia

Later sold and renamed the Lord Sandwich it was used as a troop carrier and prison ship in America's revolutionary war.

Researches say ultimately it was one of 13 ships scuttled in Newport harbour in 1778 as part of a blockade to prevent a French attack.

Sorry, this video has expired Captain Cook: A troubled 'genius'?

"So what we are looking for is a ship that looks like the Endeavour with the artefacts from the Lord Sandwich," Dr Abbass said.

"Not only do you have to find everything that says it is the Endeavour but all the other vessels have to say it is not.

The wreckages have been sitting in the busy Rhode Island harbour for almost 240 years and time has taken its toll.

"Basically the only thing that is left is the ballast rocks which were actually used for ballasts for the ship and everything else has been salvaged and removed," local dive operator Matthew Verrier said.

"They are just piles of rocks."

Researchers said test excavations on similar sites have turned up artefacts, including leather, metal, bone and ceramics.

Dr Abbass said it would cost at least $US7.5 million ($10 million) to build a facility to properly store any artefacts recovered and she is calling on Australian organisations to help fund the next step.

Excavation work to uncover the HMS Endeavour shipwreck at Newport Harbour will be difficult. An electrical cable runs across the site and the timber hull of the ship is underneath the stone and iron ballast blocks. ( ABC TV )

"We would like to share her but in a way that doesn't damage our economic benefits of taking advantage of it," she said.

"We want you to spend your money to come to Rhode Island," she said with a smile.

With the right funding Dr Abbass would hope to identify the five wrecks by 2020.

Research pointed to Newport: Captain Cook Society

Captain Cook Society president Cliff Thornton hoped the little remains of the Endeavour would be preserved in a museum.

He said all research pointed to Newport as the Endeavour's final resting place and he was not surprised by the announcement after following the progress.

Captain James Cook sailed to Australia aboard the HMS Endeavour. ( AAP:Royal Society )

"All of the RIMAP reports which I have read indicate that very little of the ships now remain," Mr Thornton said.

"I expect that the solid and strong keel may be there with a few ribs and hull timbers on either side, but I will be very pleasantly surprised if there is anything more than that.

"Hopefully what remains of the Endeavour can be conserved and placed on display in their new centre.

"It is surprising that nearly 250 years after [Captain Cook's] death new documents and artefacts are still coming to light."