PHUKET: A fresh account of the disappearance of Australian Carmel Brookes at sea off Krabi last year sheds new light on an enduring yachting mystery.

Along with the still-unexplained deaths of four young women tourists since 2009 on the holiday island of Phi Phi, what happened on the vessel Moondancer remains one of the region's most perturbing riddles.

Award-winning Australian journalist Caroline Overington delivers the results of her investigation in this month's issue of the Australian Women's Weekly.

Ms Brookes' husband, US-born marine scientist Dr Gerry Goeden, has so far been reluctant to talk to journalists.

Curious as to what happened, Overington came to Thailand and worked with Phuketwan's Chutima Sidasathian to see what they could uncover.

Most sailors are still puzzled as to why Dr Goeden and Ms Brookes decided to sail on through the night as they travelled from Penang to Phuket last year.

If they had anchored along the way, as most yachties apparently do, 59-year-old Ms Brookes would not have been alone on deck on the night of February 1.

''In emails to friends, Gerry says Carmel must have taken off her safety clip, leaned over the edge of the boat, and fallen overboard,'' Overington writes.

''It's a real tragedy, because Gerry's first wife, Ellen, also died in an accident and, just as with Carmel, he was the only other person there.

''According to a police report, which the Weekly has obtained, Ellen slipped and fell over a waterfall while walking with Gerry near Cairns, and there were no suspicious circumstances.''

Efforts are now being made to have Carmel Brookes declared dead.

But police in Krabi told the two journalists that Dr Goeden could produce no evidence of Moondancer being in Thai waters at the time Carmel Brookes vanished.

''It's an interesting development,'' Overington writes. ''Carmel is an Australian citizen, and if she's missing in international waters, as opposed to Thai waters, her disappearance could well be something that Australian police could investigate.''

Although Ms Brookes was wearing a lifejacket, her body has never been found.

On Krabi's Ko Lanta, Inspector Auttaporn Boonyakorn told the journalists that Thailand will never move to have Carmel declared dead because, as far as Thai authorities can determine, she was never there.

Dr Goeden has tried to establish that the pair landed in Thailand early in their voyage. But his version of events has not been accepted by Krabi police.

''We don't take that - we take a stamp in the passport,'' Inspector Boonyakorn said. ''And he is not able to provide the exact location where she falls from the boat.

''He says between this island and that island, that is all.''

That's good news for Carmel Brookes' family, writes Overington.

''Under Australian law, a person can be declared dead after they've been missing for seven years, after which their assets, such as Carmel's properties in Queensland, can be sold and the money given to whoever is in her Will or, in the absence of a Will, to her next-of-kin, which would be Gerry.

''Carmel's family have told the Weekly they will object to any attempt to have her declared dead without a proper investigation into how she fell.''

More serious journalism has become a feature of the Australian Women's Weekly - which is now actually a monthly - since Germany's Bauer Media Group took it over.

There is no online version of the magazine. Despite waning daily newspaper circulations, the Weekly retains a loyal audience of 2.4 million readers.