By Robert Frank

When I first wrote about the world's new largest yacht in 2007, I said it would be slightly longer than 525 feet.

Yet during construction, the length of the ship-named Eclipse and owned by Russian billionaire Roman Abramovich-started to increase. By 2010, the ship was reported to be anywhere from 530 to more than 550 feet.

Forbes and others pegged it at 557 feet-24.5 feet longer than its nearest rival, the ship Dubai, owned by Sheikh Mohammed Bin Rashi Al-Maktoum.

Now comes the widely respected Superyacht Index from SuperYacht Times and the yacht broker Camper & Nicholsons International. The Index lists Eclipse at 62.5 meters, or 533.1 feet.

Granted, 533 feet is a respectable size for the world's largest boat. That is still about the equivalent of one and a half football fields, and 78-feet longer than Larry Ellison's Rising Sun, which used to hold the title.

And we have yet to have a definitive length on the boat, since Mr. Abramovich keeps these things private.

But at 533 feet, Eclipse would be only about 18 inches longer than the Dubai. And as the folks at Luxist point out: 'Since the Dubai ruler basically owns his own shipyard now-the U.A.E.'s Platinum Yachts, where the Dubai was finished-it wouldn't take much for him to have it refitted with an extra few feet of metal to put Abramovich firmly in his place.'

That assumes of course, that Mr. Abramovich cares about matters like owning the world's largest yacht. (Mr. Abramovich's spokesman declined to comment on Eclipse or its length).

How long do you think Eclipse will hold the world record?