The great brown bird swung out of the north and, skirting the track of jets arriving at National Airport, flapped its lazy way down the Potomac.

"That," said a visitor to the members of the Washington Albacore Fleet, who were assembled on a floating dock at the Washington Sailing Marina intently watching their Wednesday night races, "is an immature bald eagle, flying right over the city."

"Very nice," responded fleet captain Daphne Byron, casting a perfunctory glance upward before returning to ornithological matters more appealing to her.

Bill Buck, one of Byron's colleagues in the busiest sailing fleet in the Nation's Capital, explained her lack of interest:

"Roger Thomas (another veteran Albacore sailor) has a fellow named Dave Metcalf in his boat with him tonight. Metcalf came down last weekend, saw our races and asked about the Albacore.

"We told him to come back tonight and try one for himself. We're all very interested in seeing how he does. You might say he's a pigeon."

And officials of the Washington Albacore fleet will take a pigeon over an eagle, any day.

Pigeons, in fact, are the staff of life for this band of dinghy sailors, who have taken a boxy, outdated, and generally unremarkable-looking British-designed day-sailor and made it the craft of choice among serious racing sailors in the capital area.

While much of the dinghy-racing world skims around in such hot little flat-bottomed rockets as the 505, 470, Flying Dutchman and Laser, the blunt-nosed, round-bottomed, tippy, 15-foot-long Albacore continues to dominate racing here, with an active fleet of about 100 surviving largely because of the parent organization's persistence in attracting and training new racers.

"It's not really a racing boat," conceded fleet lieutenant Tim Arthurs, who was waving flags into the gathering dusk to start another race for six die-hard novice boaters on an overcast night. "It's not a racing design. You don't hike out on a trapeze. There's no spinnaker."

So what's the appeal?

"Let me tell you a little about the care and feeding of a racing fleet," said Bob Harwood, a grey-haired fellow who helped organize the Albacores here in the 1960s. "You need a supply of boats; you need the right boat for where you are (which in Washington means one like the Albacore that will ghost along in light summer air); it has to be affordable; you need a training program to get new people involved; and you need a good racing program and some social events."

Once that sort of organizational scheme is established, as it has been for Albacores here, Harwood said, a fleet takes on a life of its own and becomes self-perpetuating. Like an entrenched boxing champion, it won't be knocked off its perch by the first pretty pretender that prances into the ring. The good new racers always will be attracted to the fleet because that's where the good racing is.

Said Metcalf, who enjoyed his evening of free sailing at the expense of the fleet organizers, "You should have seen these guys last weekend when I told them I was interested in the boat. They were all over me."

Every Wednesday evening from May through August the veterans convene at the Sailing Marina, which lies just south of the airport off George Washington Parkway near Alexandria, to give free lessons to novices or prospective converts like Metcalf.

And if one shows an interest in Albacores on such an evening he will not just receive a sales pitch, he will be thrust into a boat and put to work.

This the outdoor editor learned when he wandered too close to the action on Wednesday and fleet captain Byron, a tall, sun-browned Briton, shanghaied him to crew for her 15-year-old daughter, Joanna.

The instructions were hasty. "Your job," shouted Byron as the little boat sped away from the dock, "is to keep the boat flat."

That, he decided, would be easy enough to do, since an Albacore hull weighs only 240 pounds. But when he hopped to the windward rail to balance out a puff of breeze, he found that a 180-pound man can easily overbalance a 240-pound boat, and almost brought the whole affair crashing over on top of himself and his slender skipper, who was not amused.

Once he got the hang of it, the evening of racing turned out to be an athletic experience where the alternative to constant concentration and quickness was a swim, a not uncommon occurence in Albacore racing.

And it was good, fast-moving fun.

"How did you like it?" asked Roger Thomas as darkness fell.

"What do you think of Albacores now?" wondered Harwood.

"Enjoy yourself?" asked Bill Buck.

"Did you like the boat?" asked Byron.

The outdoor editor felt a curious, prickling sensation on his back, almost as if he were growing something.