Mahogany Ship Committee member John Sherwood said the discs that passionate searcher Ross Poulter found could date back to the 1400s.

Dr Sherwood said the “very interesting find” was made at Shelly Beach, west of Thunder Point, using an underwater metal detector. 

Mr Poulter has dedicated the past eight years searching for Mahogany Ship wreckage.

They think the discs, found wedged in sandstone layers, are coin weights which were used to legitimatise coins from 1440 up to the 1700s. The discs are about a centimetre in diameter and at least 95 per cent lead. 

Dr Sherwood said there was a great deal of historical interest in locating the wreck to reveal its origin.

He said a sealing party came across a shipwreck in the sand dunes near Tower Hill in 1836. The ship pre-dated European settlement and its origin was unknown. Mobile sand dunes buried the wreck, now known as the Mahogany Ship sometime after the 1880s.

Dr Sherwood said one theory for the wreck’s origin was that it was a Portuguese caravel, part of a 1522 expedition, some 250 years before Captain Cook. 

Adding more weight to the find was that the discs were discovered close to where there were reports of school children seeing a wreck, possibly the Mahogany Ship, in 1910.

Disc markings include numbers, a plus symbol, a possible rabbit and other embossing and they vary in size. “It says on the internet you shouldn’t be able to see the numbers on them and if you can see them you’re very lucky,” Mr Poulter said.

They sent the discs to the Western Australian Maritime Museum to determine the metal’s origins but couldn’t provide a conclusive answer. “We want to be sure what they are. They could be part of very old cargo. It’s something you can’t dismiss,” Dr Sherwood said. There’s a significant number of these washing in. We believe it’s from some offshore source. 

“The possibility we want to explore is that it’s linked to the Mahogany Ship,” Dr Sherwood said. 

Mr Poulter said the ongoing search was “a lot of fun and games”.

“I didn’t expect to find anything ever. It’s amazed me,” Mr Poulter said. My ambition is to do the impossible and when I came up with this find I was like ‘you’re kidding me’. 

Anyone with ideas about what the discs could be or divers with information are asked to email jsher@deakin.edu.au