In 2009, Tom Perkins, the nonpareil venture capitalist of Silicon Valley, sold the Maltese Falcon, a 289-foot futuristic Darth Vader-esque square-rigger. Reported price: $90 million. The buyer: Elena Ambrosiadou, a European hedge-fund billionaire. Then, last June, Joe Vittoria — who made a fortune as head of Avis Rent a Car when he led an LBO of the company in the 1980s — unloaded Mirabella V, the 247-foot sloop with a 292-foot mast that’s so tall the yacht can’t fit under the Golden Gate Bridge or through the Panama Canal. Price, according to industry sources: $25 million. The buyer: Rod Lewis, a billionaire Texas oil-and-gas tycoon. Now comes the 68-year-old billionaire Jim Clark, the co-founder of Netscape, Shutterfly and WebMD. He just put his splendid sailboats, Athena and Hanuman, on the market on the same day.

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Athena is a glorious 295-foot gaff-rigged schooner, with 28,000 square feet of sail area. It has enough cool gadgetry to tickle any techy who likes toys: handheld wireless touch-screens that monitor and control such ship accoutrements as music, air conditioning, and the shades in the staterooms. You can also keep track on a navigation screen of what exclusive exotic island you’re heading to. Clark, whose eccentricities led his professional crew to call their nautical universe “Jim World,” used the boat a lot as a diving platform. Athena even has a decompression chamber for divers with the bends. Asking price: $95 million, which presumably doesn’t include the South Beach white suits that Clark liked to wear aboard.

As the story goes, Clark and Perkins were in a bit of a competition about whose boat under construction would be longer. Perkins said he misled Clark by 10 feet about how long the Falcon would be — and that’s why Perkins’ is bigger. Clark maintains his is bigger, not at the waterline but because of a 33-foot figurehead-adorned bowsprit extending out from the foredeck. Boys, settle down!

The sleek 138-foot Hanuman, currently in Newport, R.I., is a replica of the great J-class racer Endeavour II from the 1930s built by Tommy Sopwith. Asking price: a mere $18 million.

Assuming Clark sells Athena, there will be only one Vanderbilt of the new yachting age left at the helm. Clark, along with Perkins and Vittoria and Barry Diller — the billionaire media mogul — each had his own exemplar of conspicuous construction. Diller’s 272-foot Eos, a Bermuda-rigged schooner, is still in his hands. (He might have an interesting time selling it, given that its bowsprit reportedly features a figurehead of his wife, Diane von Furstenberg, the fashion designer.)

Yacht owners buy and sell all the time. Clark could not be reached for comment about why he’s pulling anchor on his two prized sailing possessions. But one friend offers this speculation: “He has a newborn, and babies and sailboats don’t mix well.” In 2009, Clark married Kristy Hinze, an actress and TV host dubbed the “Aussie Angel” by the tabloids, as well as occasional Sports Illustrated swimsuit model. She’s 36 years younger than him and his fourth wife. Maybe they can buy another really, really big house together.

David A. Kaplan wrote “Mine’s Bigger: Tom Perkins and the Making of the Greatest Sailing Machine Ever Built,” which won the 2008 Gerald Loeb Award for best business book of the year.