Now that Washington has developed into a genuine sports town, a new breed of tourists is evolving. The yachtsmen are coming.

Last week a sleek and lovely 64-foot, two-masted schooner lay at the dock of the Gangplank Marina, within an easy walk of major Washington attractions.

The schooner is the When and If out of Manchester, Mass. Like all boats she has a story. Hers is exceptional.

When and If was built on a John Alden design in 1939 for Gen. George Patton, one of the nation's enduring military heroes. Patton sailed her briefly before he was called to duty in World War II. Before he departed, the general had his wonderful yacht delivered to Solomons, Md., to wait out the war.

"The local people down there (at Solomons) say he asked them to hide the boat from the government," said Steve Wedlock, When and If's current skipper.

In those days, big private yachts often were taken into custody by the military and used for a variety of purposes, including lookouts for submarines and other coastal protection.

Patton died following a car accident in 1945 and the yacht went to his wife's family. There it remained until 1973 when it was donated to a small school for youngsters with learning disabilities, the Landmark School on the north shore of Massachusetts above Boston.

She remains the When and If out of Manchester, and still spends the summers on the same mooring she's had for 40 years.

But now there's a new general and a new crew.

"This is General," Wedlock said, stroking the arched, warm back of a Siamese cat. "And this is the crew."

They clamored aft like perpetually wired-out teen-agers, which is what they are. Allen and Peter and Fred, Bill, Richard and Steve. Of the 365 Landmark School students, they were picked for this semester aboard When and If. There are worse places to go to school.

Landmark School specializes in pupils suffering from dyslexia, a disability that affects youngster's recognition of the symbols used in language and other educational skills.It used to be called "word blindness."

While dyslexics generally are of average or above-average intelligence, words, letters and numbers often appear bollixed up to them because of a brain dysfunction. No one knows why.

It's a terrible disease because it often goes undiagnosed and young people who suffer from it are labeled slow learners, or lazy, or retarded.

At first Landmark used When and If in summer seamanship programs, which basically meant a week of fun on a boat with educational side benefits.

"But it seemed a shame to have the boat just sitting there for three-fourths of the year," said Wedlock, who at age 32 holds a Coast Guard 100-ton, 100-mile offshore skipper's license.

Last year 12 pupils were selected to spend a semester aboard the boat, six at a time. She spent the winter in the Caribbean and the students flew down to board her. It worked, although the overseas location caused some problems.

This year the program was repeated except that When and If spent the winter in Solomons. That's the way it will be from now on.

Academic coordinator aboard is Kim Pedersen, a sparkling cheerful woman who said, "This is the best teaching thing I've done.

"The organization thing is great -- managing homework between chores, keeping the boat maintained. We keep the basic tutoring program and beyond that you get the wonder of the places we've been."

The switch to wintering in Solomons didn't hurt either, Wedlock said. "We don't have to convince people we're not on vacation out here. Anyway, we don't like hot weather."

In February Wedlock chopped the yacht out of the ice at Solomons so the crew could make a three-week cruise to Williamsburg.

Last week as she sat at Gangplank after her sail up the Potomac, the sweet smell of baking bread wafted from the yacht's tiny galley. "Sourdough, from scratch. Want to stay for dinner?" asked Pedersen.

The schooner is shipshape below, with the six teen-agers crammed in the center cabin, Pedersen in the tiny forepeak and Wedlock and the third staff man, Doug Gale, sharing Gen. Patton's spartan quarters amidships.

The kids clearly are having a ball.

"We find the reading-wise they do as well as they do in our conventional classes," Pedersen said. "The big thing is that they read more here, without the distraction of TV and with more time to just sit around in port."

It's a happy ship. The only problem: "Too small," Wedlock said. "We are really looking for a bigger boat so we can get more students aboard."

Not that he has anything bad to say about the beautiful When and If. "She's really an amazing boat," Wedlock said, "for handling, the way she was built, the way she has kept up."

And for the way she was, and is, used.