Domingo Lopez, the self-appointed admiral of "Nancy's Navy," watched his daughter go sailing along at one under par through the 11th hole of yesterday's second round of the 26th U.S. Women's Open.

"We're not worried about the heat," Domingo Lopez declared. "It's the older players who will suffer the most as the day drags on. We're worried about Hollis Stacy, the defending champion."

BUt Nancy Lopez started to drag anchor on the next hole, charted bogey, double bogey, bogey through the 14th to go to three over and needed a sandwedge shot to within one foot of the pin on the 18th for a birdie that enabled her to share the tournament lead with Donna Horton White and amateur Carol Semple at two-over 144.

Janet Coles and Stacy had a chance to take the lead. Coles, a second-year apro with a bachelor of science degree from UCLA, was one over with five holes to play but double-bogeyed each of the last three, Stacy was two over leaving the 17th tee only to bogey 18.

Two-time Open champion JoAnne Carner and amateur Cynthia Hill were safely in at 145, while Donna Carponi Young, the first-round leader off a 68, skyrocketed to a 78 for 146.

For the second straight round, Lopez was unable to carry her strong game through the closing holes.

The 21-year-old winner of seven LPGA tournaments and more than $135,000 this season played exceptionally steady golf over the front nine and appeared ready to move out to a comfortable lead over this large field when she sand wedged the ball to within 10 feet of the pin on the par-5 11th and made the birdie putt.

"I felt real good, right there," she said. "Then my four-iron to the green on 12 caught a trap and I missed a five-footer for par . . . and I got angry - better say, aggravated - at 13."

She had reason. Her three-iron shot hooked far to the left. She chipped back nicely, down a slope, to 10 feet of the pin - only to three-putt from there, blowing a one-footer for a double bogey.

Lopez missed a six-foot putt on 14, for another bogey, and needed a 15-footer on 17 to save par before finally getting her shot game back together on the last hole. She wound up with 73.

Semple carded the best score, 71. She is an analyst of municipal bonds for a Pittsburgh bank who once considered turning pro only to decide she "didn't want to play that much."

"Quite often," Semple observed, amateurs aren't able to sustain their play for four days against professionals. I usually can't substain it either. I don't know what happened to me."

White has put together 72-72, making her the steadiest of the leaders thus far. "The difference was the course played three shots harder today, so I don't think I really shot the same thing," she said. "The wind picked up on the back side today and the heat's starting to get to everybody."

Young needed more than half an hour to cool off from her 78 before meeting the press.

"I'm gonna go get drunk tonight, and I don't even drink," she began. "This was the worst I've hit it all year, after yesterday (68) was the best I'd hit it.

"I don't know," the 1969-70 Open winner continued. "Everything was right to left, too much. I had an optic problem, among putting and other problems, trying to get a line. It's hard to concentrate when you don't know what's wrong. It got so bad I got mad, at myself, and I was just trying to get the ball on the club head someplace. Anyplace.

"But I guess Jack Nicklaus even has days like this, once in a while."

Apprised of Nicklaus' 64 at Philadelphia yesterday, Young quickly added, "but not often, right?"

Young's snap-hooks off the tee repeatedly got her in trouble. Her putting was as bad as she suffered through seven bogeys without one birdie.

"I did not hit one solid shot, or putt one solid putt," she concluded. "The trouble was, the only person I could get mad at out there was myself . . . and maybe at the USGA people a little. For the first round the pin placements were fair. Yesterday they were cute, real cute. That's why you see what's happening with the (higher) scores today."

Domingo Lopez is 63 and has his hands full here shepherding Nancy's sister, niece, nephew and the daughter of her college coach at Tulsa around the grounds. The niece wore a red T-shirt proclaiming: "Aunt Nancy Lopez, Number One."

"It's so important to her, because she's been second twice, and because it's the one she wanted most to winfor her mother before her mother died," he said. "I think she'll do it this time.

"I plan to go with Nancy more and more," her father declared. "We started out together, teaching her, when she was 8. I've developed a champion top golfer and a top bodyshop man, my son-in-law. My shop's back home, in Roswell (N.M.). His is in Gardens, Calif."

"I still have four guys working in my body shop, but we're not making too much money. I think I'll give it up next year, to follow Nancy more. She's going to be going all over. She's going to be playing later this year with (Lee) Trevino in England and in a match play tournament later in Tokyo. They'll love her everywhere 'cause she plays for the people, not just the money.