A number of factors including an unusually large rogue wave may have led to the fatal boating accident just south of the Golden Gate on Sunday that killed an El Sobrante couple, who friends say were experienced sailors.

Jeffrey Easterling, 59, was the skipper when he and his wife, Beth Easterling 50, fell or were swept overboard from their sailboat in the waters west of the Cliff House restaurant in San Francisco.

He had sailed the 33-foot-long Barcarolle for more than 25 years.

"He was a very good sailor and a very careful sailor," said Bonnie Russell, who first went sailing aboard the Barcarolle in the 1980s. "Jeff always conducted person-overboard drills, and was always very, very careful.

"I fell overboard myself once in San Francisco Bay, and he brought the boat about (on a new course) to pick me up immediately. So I was floored when I heard what happened.

"He always had the boat radio on and tuned to Channel 16 (the emergency channel), so if nobody heard an emergency radio call it must have happened very quickly."

The Barcarolle was a Ranger 33, a vessel made of fiberglass and generally considered to be a comfortable and safe boat, particularly for long cruising trips.

The Easterlings had planned to take a long cruising trip, possibly as far at Cabo San Lucas at the end of the Baja California peninsula. Their weekend trip to Pillar Point, on the San Mateo County coast, was apparently a shakedown voyage in preparation for the longer trip, said Gina Ortolan, Beth Easterling's daughter.

They were believed to have left from Pillar Point Harbor, more than 20 sea miles south of the Golden Gate, about noon. At 4:30 p.m., personnel at the Cliff House spotted what was thought to be a sailboat capsized and in distress and called the Coast Guard.

A Coast Guard rescue boat found the Barcarolle afloat, with the sails set, and no one aboard. Some of the boat's windows were smashed.

Beth Easterling's body was found near Seal Rocks on Sunday night. Jeffrey Easterling's body was found Monday morning on San Francisco's Ocean Beach, some distance away. It was not known whether the couple were wearing life jackets.

Kimball Livingston, who has written a book on sailing on the bay, said he saw the Barcarolle just before it ran aground.

No one was aboard and it was clearly out of control, Livingston said.

The couple had been married a little more than five years; Jeffrey Easterling was a widower when he met Elizabeth Ortolan, who was called Beth. Beth Easterling loved sailing and went every chance she could get.

E-mail Carl Nolte at cnolte@sfchronicle.com.

This article appeared on page C - 4 of the San Francisco Chronicle