The ice is gone, but the good ship "Wanderlust" is still here, moored to a Fort Washington Marina pier that its owners planned to leave last November when Washington's most recent Ice Age set in.

Tom and Liz Mac Leod, their two children, Australian terrier, two cats - one with 13 toes, the other with 15 - and bicycles lashed on their boat's bow, had planned to sail their 35-foot powerboat to Florida. They had sold their houseboat in Daytona to buy and restore the "Wanderlust," and were looking forward to establishing a new watery home in Tampa, where macLeod says "the water is crystal clear, you can see the bottom even in 20 or 30 feet of water."

But after they became solidly ensconced at the the marina, in ice that grew to almost two feet thick, they enrolled their children in Prince George's County's Harmony hall school, covered their portholes and hatches with plastic and settled down to a long winter's nap with the marina's 50 other resident mariners.

Fort Washington Marina, which will be taken over by the National Park Service in 1980 and its "live-aboards" evicted (the Park Service does not permit permanent residents at any of the four marinas it operates here) is one of only a few Washington area marinas where people can live "tax-free" on the water, says Tom Wilson, who bought the marina several years ago.

Living afloat is relatively cheap, says Wilson, because boats, like mobile homes, are considered personal property and Marylan dhas no personal property tax. "The average 40-foot houseboat, say five years old, costs only about $10,000 . . . and the only expenses are the boat's mortgage, a slip fee that runs usually from $50 to $100 a month for live-aboards who heat their cabins with electric heaters.

The MacLeods arrived with a Florida wardrobe but quickly acquired two electric heaters, a gas stove and lots of sweaters. "We shiver when we think of Florida but then we used to live in a cabin in th Poconos and just thinking how cold we were there makes us feel warm and cozy here," says Liz MacLeod.

A carpenter, MacLeod bought the "Wanderlust" "sitting in a field" beside the marina last summer, when it was "filled with dirt and 10,000 spiders." He restored the 1950 Steelcraft cruiser and the family still plans to sail down the Intracoastal Waterway to Florida. "But now we'll wait till school's over for the boys," says MacLeod.

The boys, the two cats and the dog all appeared to be enjoying themselves, on the boat, the docks, out on the ice - where ice hockey games played around the boats was the major winter sport - and in the water.

The Australian terrier has fallen in several times "and I fell in three times," says 8-year-old Eric MacLeod. "I like to fall in."