The gasoline shortage that's keeping many motorists off the highways on weekends also is discouraging boaters from venturing too far from their slips and boat ramps, according to area marina operators.

From Chesapeake Beach to the Patuxent, Potomac and Occoquan Rivers, the theme is the same with some variations: Many people can't get the gas to get to their boats. Many others are finding marine gas pump operators pumping less gas, closing sooner, and limiting individual purchases.

Consequently, marina operators say, those going boating are not venturing out very far. They are, according to Paul Hoffmaster of Hoffmaster's Masrine in Woodbridge, "practicing self-control" using their berthed boats as summer cottages and trading the pleasures of open water for the camaraderie of the pier.

Some marina operators also report a sharp increase in the use of sailboats, which use little fuel, and a noticeable rise in the number of people selling their vessels.

It is a situastion that gives rise to some paradoxes: People who can't get gas to drive to their boats are helping somewhat-to ease the marine fuel shortage, but the shortage still persists.

At Kellam's Marrine in Chesapeake Beach, 35 miles from Washington, weekend traffic in motor boats towed in by car is down as much as 50 percent since last year. Gas allocations are down 30 percent, and Kellam's pumps have run dry during the third week of each of the last two months.

But a few miles north, in the Anne Arundel County community of Deale, there are boats and fuel aplenty according to marina operators.

"My husband said he could get 5,000 gallons on the dock but can't get gas to drive down to D.C.," said a woman at Scuttlebutt Marina.

Another paradox: Those who somehow make it over to the Eastern Shore are in good shape, in some places. At Queen Anne's Marina, on Kent Island, clammers and crabbers have unlimited fuel while recreational boaters are limited to 10gallons. But farther south, in the popular Talbot County port of St. Michael's, marinas report no fuel shortage.

To avoid an anticipated gas crunch closer to home, marinas in the metropolitan area have taken measures to limit gas sales in the face of lower supplies. Alexandria's Old Town Yacht Basin, for example, sells gas three days a week, down from six when supplies were more plentiful.

"All we're trying to do is keep everyone afloat," said Old Town operator Katie Lang. "We have not yet set any (purchase limit) but we may have to before the end of June to make sure we have enough for the Fourth of July."

At the Fort Washington Marina, on the Maryland side of the Potomac five miles below the Woodrow Wilson bridge, owner Tom Wilson has limited gas sales to Saturdays from 10 a.m. to 6 p.m. or "by appointment" for regular customers.

There's no rationing Yet at the Columbia Island Marina near the Pentagon. "People who rent slips are Upset because we sell to people who aren't in the marina," said Guy Blocker, who works there. But so far, except for a brief tank-topping spurt a week ago, there have been no problems, he said.

Marina operators say the wet weather of recent weeks has helped dampen the marine fuel crisis somewhat. Should demand increase with fairer weather, Fort Washington's Wilson predicted, "We're gonna be in bad shape."

Those who venture out now sometimes do so at their own risk. "About a dozen boats are being towed in on the weekend out of gas, double the normal number," Wilson said.

Tuesday, Capt. Harry Phillips III was able to talk the people at Rod 'N' Reel at Chesapeake Beach into letting him buy enough gas to reach his home port of Middle River, just above Baltimore. Phillips operates Miss Jane 11, a charter fishing boat. Rod 'N' Reel, which has its own 38-boat fleet, has stopped selling fuel to outsiders.

"We're kind of sweating it out whether we'll have enough for our own."said Jimmy Johnson, who works in the Rod 'N' Reel tackle shop. "We're being kept almost on a string as to what we're gonna get from month to month. Things are getting rather difficult."

Despite reduced allocations of fuel, there was no apparent gloom a few miles away at Deale.

"We've got gas coming in this afternoon," Roger Ramsey, owner of Berlits Marine Anchorage, said one day this week. His fuel supply had run out 4:30 p.m. the day before for the first time this year.

"I try to sell boats," he said. "Why would I want a story about the shortage of gas? Probably the less said about it, the better." CAPTION: Picture, Charter fishing Capt. Harry Phillips fills his boat at Chesapeake Beach. By James M. Thresher - The Washington Post