As public boat ramps and private marinas dwindle in number in Southwest Florida and the nation, developers have discovered that boat slips can command prices as high as waterfront condominiums.

"We lost 1,620 boat slips [in Florida] last year," says Steeven Knight of Sanibel Harbour Yacht Club and a partner in the proposed Sarasota Harbour Yacht Club on Whitaker Bayou in north Sarasota. "The Wall Street Journal says supply will never catch up."

That's why Knight, who is developing the Sarasota club with Sarasota businessman Charles Githler, and Mike Carter, the developer/owner of Riviera Dunes Marina, just north of the Manatee River off U.S. 301 in Palmetto, are "condominiumizing" boat slips. Carter says this new concept is popular on the east coast and in Key West and is starting to move up the west coast." Instead of renting slips or dry boat racks daily, weekly or monthly, boat owners-and investors, of course-buy them like any real property.

Carter, who just finished the process of "condominiumizing" his five-year-old marina's 220 slips-also known as dockominiums-says the marina can accommodate boats from 30 to 120 feet in length. Slip buyers own the bottom of the basin underneath their boat, the water that fills the length of the slip, and the column of air above it. They share access with other slip owners to the common areas, such as the docks that lead to the slips and the parking lot at the marina. The facility also offers a restaurant, two heated pools and concierge service for slip owners. The marina is more than just a clean and protected place to keep a boat, Carter says. Riviera Dunes has become a vacation destination. The facility is operated like a hotel, "only you own the room," he says.

Carter is able to sell the slips because he owns the marina itself. Most marinas operate over sovereign lands owned by the state and they are only able to sell leases. But Riviera Dunes was formerly a 90-acre dolomite mine, active in the 1950s but shut down in the 1960s. It sat dormant for decades until Carter bought the land and obtained a permit to allow it to be cleaned up and turned into the 18-foot-deep harbor it is today. Sarasota Harbour Yacht Club is able to sell slips because it owns the submerged land within its property boundaries.

Slip values have tripled since they were first offered for sale about 18 months ago, Carter says. The first slip sold for $2,000 a linear foot. Slips now go for $6,000 a foot. This means a 50-foot slip that once sold for $100,000 now goes for $300,000. Approximately 40 percent of the slips have sold, Carter says, while others are rented. Riviera Dunes has an occupancy rate of 70 percent to 85 percent.

Most of the owners and renters live and work about an hour's drive away in Lakeland or Tampa. "Their boat is their vacation house, only it floats," Carter says. They travel to the marina on Fridays and spend the weekend with family and friends living the island life. One of the tenants, a Houston family, flies to the area every six weeks or so to spend a long weekend on their 65-foot yacht. "They've never left the dock in three years," Carter says.

Meanwhile, the area around the facility continues to grow. Corvus International is building Bel Mare, three 15-story luxury condominium towers, on the north side of the marina. And five seven-story condominiums, built by Opus South Development, are going up on the south side.

Pending approval by the city of Sarasota, Knight's project on Whitaker Bayou will include 290 fully enclosed racks and 38 wet slips. Just a week after opening the sales office, Knight had sold five wet slips and 42 dry. Dry slips range from 30 to 45 feet in length and cost between $107,000 and $172,000. Wet slips range in length from 35 to 70 feet and cost $240,000 to $500,000. Knight calculates slips are running about $7,700 per linear foot. In Naples, prices for slips in a similar project are up to $12,500 a foot.

Owners of Sarasota Harbour Yacht Club slips will also enjoy concierge service, which means they can request their boat be readied for an excursion and stocked with food and drink. When the boat comes back, marina staff will wash it and flush out the engine. The facility will also include a clubhouse with dining room, lounge, spa and exercise facility, showers, tiki hut and barbecue area. The monthly dues are $350, but Knight says members get their gas, food and liquor at wholesale prices. "We'll even cut the lemons and limes for your drinks before you go out," he says.