SAN DIEGO – Dennis Conner’s Stars & Stripes became the latest Sunday casualty in the demolition derby otherwise known as the America’s Cup.

The racing sloop took on water due to apparent keel damage and was forced out of its semifinal race with Young America on Sunday.

Preliminary reports were that the damage was in the area of the keel box, where the keel is bolted to the hull. The 75-foot yacht was towed back into its San Diego Bay compound. The cause of the accident and the extent of the damage remained unclear. The yacht was to be inspected Sunday evening.

“At this point, all I can tell you is it’s a serious problem, and certainly not one we were looking forward to,” Conner said at a late afternoon news conference.

“We’re going to do everything humanly possible to make sure we’re out there Tuesday.”

Sundays have proven to be devastating days for America’s Cup yachts. On March 5, oneAustralia broke in two and sank during a race. The next week, Young America sustained serious hull damage when it hit a large wave while being towed out to a practice sail.

Repair time for Stars & Stripes would depend on the severity of the damage, as carbon-fiber racers require a curing period whenever repairs are made.

Following the accident, Young America, skippered by Kevin Mahaney of Bangor, continued to sail around the course and became the first syndicate to reach the Citizen Cup defender finals. Young America collected its fourth semifinal victory.

Conner, who has won the America’s Cup three times and lost it once, is battling America ‘s Mighty Mary for the final spot in th defender finals. Stars & Stripes has a layday on Monday and is scheduled to race Mighty Mary on Tuesday.

In wind of about 11 knots, Stars & Stripes was trailing Young America by several boat lengths sailing the upwind third leg and approaching the halfway point when it suddenly stalled.

Conner said no one on deck heard a noise, but that Wally Henry, who was below deck packing a sail, reported that the boat was taking on water.

“I didn’t really hear what he said, but it was said in such a tone that it got our attention right away,” Conner said.

After Conner’s press conference, Mahaney said his crew members reported that prior to the accident, Stars & Stripes appeared to hit a wave awkwardly while tacking.

Stars & Stripes crew members began emergency procedures, dropping the sails and bailing water with buckets. Pumps were brought on board from the team’s tender and a U.S. Coast Guard vessel. Flotation buoys were attached to the hull and the top of the 110-foot mast.

Conner said that once the pumps were up and going they were removing approximately 55 gallons of water per minute. But he didn’t think the yacht would end up going down like oneAustralia did.

“I couldn’t say anytime you’re taking that kind of water on, that you’re very comfortable,” he said. “No one asked `Are we going down, Dennis?”‘

If it had been more serious, “it would have gotten my attention because as you all know, I don’t swim. I would have been looking for that tender myself.”

On the Louis Vuitton challenger course Sunday, undefeated Team New Zealand moved closer to a finals berth by outsailing winless Nippon on all six legs to win by 3:54.

OneAustralia kept ahead of Chris Dickson’s NZL-39 the whole way around the course and won the important match by 40 seconds. The two teams are tied in the battle for the second berth in the finals.

This has been the most destructive regatta in the 144-year history of the America’s Cup.

The worst accident was oneAustralia’s newest sailboat breaking in half and sinking in heavy winds and high seas.

Also on March 5, France 3’s mast snapped in two, Mighty Mary sustained hull damage and Stars & Stripes had rigging problems.