Photo: © 2010 AAP/GREG WOOD

The Sail-World website claims Watson's attempt to become the youngest person to ever sail solo and unassisted around the world was flawed from the start.

"Jessica, with all of her braving of the Southern Ocean, will have completed a circumnavigation but not to the satisfaction of the WSSRC for Round the World record purposes," reads the article.

"It is a matter of record that the WSSRC advised Jessica's team prior to her departure that her route would fall short of the RTW minimum distance."

Watson this week rounded the southern tip of Tasmania and set a course for Sydney Harbour, where she is expected to wrap up her grueling 23,000 nautical mile trip next weekend.

But Sail-World says she has miscalculated and will in fact fall just short of the 21,600 nautical miles she needs to clock up for an offically recognised circumnavigation.

"It's a precise world. Another young Australian sailor David Dicks missed out on a 'non-stop unassisted' circumnavigation in 1996 by accepting one small bolt mid-ocean in order to repair his yacht."

But Watson's manager, Andrew Fraser, has dismissed the suggestion as sour grapes.

"This is typical of the sailing blog forums," he told The Age.

"The bottom line is, and this is quoted from [the WSSRC], to sail around the world a vessel must start and return from the same point, cross all meridians of longitude and cross the equator.

"She’s done all of that."