(CNN) -- A missing British yacht was found overturned with its keel broken, causing a breech in the hull, about 1,000 miles off Massachusetts, but the four-man crew is still missing, the U.S. Coast Guard said Friday.
A U.S. Navy helicopter spotted the capsized the 39-foot Cheeki Rafiki sailboat within a Coast Guard search area east of Cape Cod, officials said.
A Navy boat crew and surface swimmer assessed the damaged boat, but the swimmer found no signs of the crew after knocking on the hull and reaching below the waterline, the Coast Guard said.
Search crews looked Friday for a bright-colored life raft and the missing sailors, who the Royal Yachting Association identified as skipper Andrew Bridge, 21; Steve Warren, 52; Paul Goslin, 56; and James Male, 23.
As expected, the Coast Guard suspended the search at 10 p.m. ET Friday -- which was midnight in the search zone -- after scouring another 21,000 square miles.
No sailors had been found as of then. In a statement Friday night, the Coast Guard hinted that the prospects anyone would be found alive are slim.
"Based on the extreme sea conditions at the time of distress, but assuming best-case emergency equipment, the estimated survival time past the time of distress was approximately 20 hours," the Coast Guard said. "Searches were suspended nearly 200 hours after the time of distress."
The four British sailors have been missing in the Atlantic Ocean for more than a week.
The 39-foot (12 meters) Cheeki Rafiki was sailing from the Caribbean to the United Kingdom on May 15 when it began taking on water, according to Doug Innes, the yacht's managing agent.
Innes said contact was lost with the boat -- which he describes as "a performance racer/cruiser" that is "equipped for trans-Atlantic sailing and racing" -- early the next morning. He added that he believed the crew abandoned to the life raft.
But the U.S. Coast Guard appeared to dispel that notion, saying Friday night that "the boat's life raft was secured in its storage space ... indicating the crew had not been able to use it for emergency purposes."
CNN's Greg Botelho, Steve Almasy and Kevin Conlon contributed to this report.