The 12-meter yachts Enterprise and Independence sparred to a draw today in trials to pick an America's Cup defender as Atlanta Braves owner Ted Turner and his Courageous rested on a 3-0 record.

The races gave no clear indication whether either lagging contender can muster the teamwork and tactics needed to halt Courageous. Courageous defeated Enterprise twice in the Tuesday opener and beat Independence in a storm-shortened race Wednesday.

The round-robin series could continue until Sept. 8. It will end when the New York yacht Club decides which boat will defend yachting's most coveted prize against a foreign challenger in finals beginning Sept. 13.

Enterprise, skippered by sailmaker Lowell North of San Diego, was ahead by 27 seconds at the start of the first race, led all the way and crossed the finish line 1:02 ahead of independence.

"He was following the oldest rule in sailing," said a spectator aboard one of about 80 nearby craft. "Covering your opponent (a position tactic that may cut of his wind) is the surest way to win.

With sailmaker Ted Hood of Marblehead, Mass., at the helm, Independence turned the tables in the second race on a four-leg course. In 18-knot winds and two to four-foot seas, she took the start by two seconds.

She bounced to a lead of about 20 seconds on the first and second marks, sprinted to a 1:07 margin by the third mark and lost ground for a 58-second advantage at the finish.

In the competition to determine the foreign challenger, Sweden's Sverige handed Gretel II her second straight loss today, leaving the Australian 12-meter yacht facing a do-or-die situation in the challengers semifinals.

Sverige, which lost the start by a mere second, passed Gretel II on the first windward leg and gradually expanded her lead.