Russell Long, a handsome young sailboat racer, got a call on April 1, 1979, from Ted Turner, a handsome famous sailboat racer.

Turner was offering a boat to the young man, a 12-meter yacht called Independance, saying he needed someone to race against his boat, Courageous. Long said he had never sailed a 12-meter, but why not?

Long first chartered the boat. Then he boucht it. Then he had it taken apart and rebuilt into a new boat he calls clipper.

On the second day of the America's Cup trails today to select a U.S. defender for 1980, the young man clobbered his famous mentor in one race and defeated him decisively in a second, raising a simple question.

In the end who is going to get to say, "April Fool?"

Could Turner, who successfully defended the cup in 1977 and who is favored to do it again this year, come to rue the day he picked up the phone?

"You could quote me as saying Courageous had a bad day on Rhode Island Sound," Turner said at the dock today when the races were done. "Clipper was magnificent."

The trials were conducted under the eyes of the America's Cup selection committee, which will decide who will defend the cup against the foreign challenger in September.

Long and his crew of youngsters ("we're still the new kids; we don't know a lot about 12-meter racing, " he claims) left Turner wallowing in deadd air at the start of the first race and beat Courageous over the start by 10 seconds in the second and final race of the day.

Long led all the way in both contests and extended his lead on almost every leg, finished with a 1-minute 33-second advantage the first time around and 30-second edge in the final race.

"Surprised?" asked the 24-year old former captain of the Harvard sailing team "I think everybody was surprised."

They were surprised at Banister's Warf, where both Courageous and Clipper tie up, to break out four bottles of champagne to toast the new kids.

Long thought that was a little much and ordered the bubbly shipped along to a friend celebrating a birthday.

"It's only the first of two races," he said and smiled. "Nothing important."

The boats dueled most of the day in light air, with the start of racing delayed more than an hour for lack of wind. When the breeze picked up to 4 to 6 knots, two practice starts were run and Turner won both.

But when it came time to race, Clipper's tactician, Andy Rose, turned the tables, pinning Turner as they approached the starting line and finally forcing him out into the spectator fleet.

Clipper bore upwind and crossed the line 1 minute 33 seconds ahead of Courageous, which never came close to catchin up on the 11-mile, five leg course.

"That's the patented Andy Rose slam-dunk start," said Dave Pedrick, Clipper's designer, who was watching from the yact's tender.

Long took control again at the start of the second race on a 10-mile, foor-leg course. The winds had picked up to 8 to 10 knots. Long again forced Courageous to jibe while he pointed up and slipped over the line.

By the first mark 2 1/2 miles away, he had stretched a 10 second lead to 33 seconds; by the next mark he was 44 seconds and at the finish he was in the lead by about a half-minute.

There were smiles and cheers aboard Clipper, everybodys underdog.

"Hey," said Tom O'Brien, the navigator. "You have to understand something. We really expect to win this thing. We're not here for any other reason."

Long, a son of wealthy New York shipping magnate Summer (Huey) Long, and his exuberant crew still have a long road to travel. Their boat is slightly more than 2 months old, though it proved today its design is fast.

The cerw is stol working out kinks. And it must do battle all summer not only with Turner, whose crew from 1977 tryouts remains intact, but also with Dennis Conner and his bot Freedom, considered the second favorite behind Turner.

But tonight the Clipper crew was rejoicing.

"It's nice," said Long, "to be out in fornt in the clean air for a change."