"It was to have been a quiet evening at home. Home is the Busted Flush, a 52-foot barge-type houseboat, Slip F-18, Bahia Mar, Lauderdale."

So begins The Deep Blue Goodbye, the first in Sarasota author John D. MacDonald's series of mystery novels featuring Travis McGee, the knight-errant hero whose base of operations is the boat he won in a poker game. When the book was published in 1964, and for the next 21 years until MacDonald released The Lonely Silver Rain just before his death in 1986, a 52-foot boat seemed like quite a grand vessel. It was surely enough to help ol' Trav woo his share of women and entertain friends in decent fashion.

But despite the brass plaque at the Bahia Mar Marina honoring the fictional boat, and Slip F-18's designation as one of Florida's official "Literary Landmarks," the marina's other erstwhile residents might not think too highly of a puny 52-footer should it tie off next to their yachts these days.

"Let's put it this way: I have clients who buy 80-foot tenders for their yachts," says yacht salesman Peter Croke. "For them, a 52-foot boat is barely a dinghy."

Welcome to the rarified world of mega-yachts, floating palaces that are now topping out at 400-plus feet, where on-board amenities include such indulgences as basketball courts, helicopter pads and personal submarines. Ownership of the truly big yachts is the purview of folks like billionaire Microsoft co-founder Paul Allen (the 414-foot Octopus), Oracle Corp. chief Larry Ellison (the 452-foot Rising Sun) and certain oil gazillionaires (one Saudi royal family member is expected to launch the 526-foot Platinum in 2006); but Southwest Florida residents also own their fair share of big yachts, some among the largest in the world.

Father-and-son real estate developers Raymond and Scott Lutgert, of Naples, last year launched the 164-foot Andale, from Italian shipbuilder Codacasa. It has an elevator to transport guests from deck to deck and, when the Lutgerts aren't entertaining on it, charters for $230,000 a week. Naples residents Lee and Penny Anderson lay claim to Katherine, a 177-footer that regularly cruises the Mediterranean. And Sarasota automobile dealer Vern Buchanan is proud master of the Entrepreneur, a 110-foot craft launched in 2004, which comes with a surround-sound theater, a hot tub and a 32-foot center console boat that can be towed behind and used for water skiing, scuba diving or sport fishing.

While folks who call Florida's Gulf coast home are among the most ardent buyers of big yachts, that doesn't necessarily translate into seeing them out on our waters. "I'd say the Naples-Sarasota area easily ranks as one of the highest per capita yacht ownership areas in the U.S.," says Jim Gilbert, publishing director of Showboats International, a slick monthly magazine based in Fort Lauderdale and dedicated to the mega-yacht lifestyle. "It's hard to tell, of course, because when you get yachts of this size people don't exactly park them in their back yards."

There are several reasons for that. For one, the Gulf's shoals and shallow waters make for tricky navigating. Plus, few marinas along Florida's west coast are equipped to handle yachts longer than 140 feet.

Vern Buchanan bought his first boat, a 16-footer, when he was 18.

"I've been going upwards ever since. Had a 54-footer, then a 70-footer and now the 110-footer," says Buchanan. "I'm happy with it for the foreseeable future. But will I get an even bigger one? Never say never."

One reason Buchanan bought Entrepreneur was because the yacht's six-foot draft was suitable to Gulf waters. "Lots of the big boats don't make it to the Gulf, but I couldn't imagine not having mine here, at least part of the year," says Buchanan. "Sarasota is just such a mecca for yachting."

The big yachts tend to stick to a standard circuit: the Caribbean and Bahamas in the winter, the Mediterranean in the summer, with stops in Fort Lauderdale along the way. But then, yachts of this size can go just about anywhere they want to, provided there's plenty of deep water. A yacht like the Lutgerts' 164-footer typically has a cruising range of at least 5,000 miles, making it easy enough to plan a round-the-world cruise. Just have plenty of cash on hand when that 31,000-gallon gas tank hits empty.

Not only is Fort Lauderdale home to the Bahia Mar Marina and other notable big-yacht docks, it's also the site each fall of the Fort Lauderdale International Boat Show, the largest in-water boat show in the world. When the big yachts are put up for sale, this is where you'll find them. Fort Lauderdale is also home to a sizeable population of "boat people," whether trained crew and captains for the big boats or the skilled mechanics and craftspeople who keep them running smoothly and looking good.