Eric Clapton once owned this Extremely Rare Rolex watch dubbed "The Yachtmaster Daytona which was a Prototype Rolex and was never offered to the public. It is fascinating to see how Rolex experimented with the nautical theme in the 60s and early 70s be creating a 39MM Yachtmaster. Of course, Rolex did not bring the current Yachtmaster to market until decades later.
Eric Clapton's Rolex Yacht-Master prototype sold at a Christie's Auction in 2003 for $125,000, and Eric Clapton donated the proceeds to his Crossroads Foundation. His Rolex Yacht-Master is picture below and appears courtesy of Christie's Auction House.
Here is another photo of Eric Clapton's Rolex Yacht-Master Prototype Reference 6239/6242. There are only 3 known examples of the Rolex Yacht-Master Prototype. The first is this one that was owned by Eric Clapton. The second one is owned by John Goldberger, and the last one is owned by Rolex and kept in their private collection and it has a special bezel [Reference 6542].
Source : Jake's Rolex Blog