About 2:30 a.m., after failed attempts to pump water out of the sinking boat, the six people were transferred one at a time to the rescue vessel without injury. Authorities did not identify them.
The 68-foot sailboat had left Fort Lauderdale, Fla., on Friday and was headed to Nantucket, Mass.
Harker said the rescue crew spotted the sailboat when they were about a half-mile away. On cloudless nights with calm conditions, visibility can be up to three miles, he said.
With the helicopter lighting the way, the crew drifted toward the troubled boat. At one point, a Coast Guard member was lowered from the helicopter onto the sailboat, where he tried to pump out water. But the boat had taken on too much already.
Rough conditions further hindered the operation, pulling the rescue boat away from the sailboat as it tried to get near.
"It was hard getting alongside it," Harker said. "We had a tough time."
Once the boats were secured, the Coast Guard member already aboard the sailboat helped transfer the passengers, which Harker said took about 30 minutes.
The crew then returned to the Cape May station.
Harker said the boat was still adrift Thursday.