For three years, Kurt Askin berthed his 41-foot sailboat "Sharol" at the Washington Sailboat Marina along the Alexandria waterfront. To Askin, an economist for the Environmental Protection Agency, the location was ideal: It was within minutes of his Falls Church home, the slip fees were cheap and the ambience, well, inpretentious.

But two weeks ago, Askin angrily hoisted the craft, said by admirers to be worth at least $100,000, from the Potomac and headed for calmer waters.

What put the wind to Askin's sails was the discovery that his safe harbor was no longer a tax shelter. Early in October, Howard Holton, Alexandria's director of finance, launched an attack on the hundreds of boats that fill the city's marinas and escape his tax bills by being registered in either the District of Columbia or Maryland. Neither jurisdiction levies personal property taxes on boats, a fact that enables many yachtsmen to escape paying thousands of dollars each year.

For Askin alone, the tab for his current and delinquent boat taxes could run to well over $10,000. "If I had known about the tax I would never have moored my boat in Alexandria," complains Askins, a lean man with graying hair who was one of 200 boat owners to jam a recent protest meeting over Alexandria's effort to tax them.

When Askin heard of the tax drive, he said he felt insulted and hopping mad" and more than willing to join with the others in challenging the issue in federal court. The boaters hope to take the issue before a U.S. judge in Alexandria today but the two sides say that it is unlikely that the issue will be resolved in a single court hearing.

What infuriates the boaters is their doubt that Alexandria has the right to tax their vessels. The District of Columbia, not Virginia, owns the waters in which their boats are floating.

"We don't contest the fact that the water belongs to the District of Columbia, but the boats are moored in what we consider the Alexandria harbor and tied to piers that are attached to Alexandria land," insists Assistant City Attorney Nolan Dawkins. "It doesn't make a difference where these people live."

The tax collector's efforts have aroused the boatmen like nothing since the flap over a proposed regulation that would have required small-boat owners in Virginia to install raw sewage processing tanks in their vessels. That proposal was dropped after boat owners around the state descended in rage on the state legislature.

Thus far, Holton, an unassuming bureaucrat, has been deaf to the watermen. "I don't understand what the problem is," he said. "There's always been a tax on boats in Virginia.

"Just because we haven't sent out notices every year, doesn't mean they don't owe it. Every year, we have an emphasis in a different area [of tax collection]. This year, it just happens to be boats," Holton explained.

If anyone's to blame in the current flap, Holton says, it's the boat owners. "They should have called the city to see if they owed any taxes. If I had been a boat owner I would have called," Holton declared with the tone of a man who has heard it all one too many times.

The issue is the latest of many hassles over the Alexandria waterfront. For the past seven years, city and federal officials have battled in federal courts over ownership of the land along the river's edge.

Until the question of whether the city has the power to tax the boats is decided in the courts, lawyer Dawkins said the city has agreed to hold off mailing the 200 tax bills waiting in the assessor's office. Seventy-six already had been sent since October. Boat owners say that if the federal court will not hear their pleas, they will appeal to political leaders. Whatever the decision, they say, the fight is far from finished.

"The city is being very shortsighted if it thinks that this tax is going to work . . . there are hundreds of questions they haven't looked into," said Julia Coyle, fleet captain of the Daingerfield Island Cruising Fleet, a group that sails out of the Washington Sailboat Marina.

Some boat owners claims the tax will drive sailors from Alexandria to friendlier waters, like the Prince George's County marina where Askin took his boat.

"The city is always talking about improving the waterfront, but with this tax people are just going to leave and dock in different areas," said Elli Abramson, a feisty D.C. resident who berths her 21-foot sailboat at the Washington Sailboat Marina.

"Many of the people who sail here can't afford to pay the tax . . . people tend to feel that all boat people are rich people," she said. "But these are people who put every spare bit of money they have into their boats. You might look and say, 'my god, that person has a $10,000 boat and should be able to afford the tax.' But look at their houses, look at their cars. Most have had their cars longer than their boats.

"Sailing will continue in the Potomac, because sailing will always survive -- but this will destroy the Alexandria waterfront."