Dr. Edmund B. “Ned” Cabot, a retired surgeon and scion of a Boston Brahmin family, drowned Saturday off the coast of Newfoundland when a rogue wave swept him from his yacht, the Royal Canadian Mounted Police said Sunday.

Cabot, 69, a lifelong sailor, was on the final leg of a journey he and friends had pursued over the past seven summers on his sloop, Cielita, that had taken them from Nova Scotia through Greenland, Iceland, and Scotland to the coast of Norway, said Peter B. Ellis, a friend of Cabot’s for 40 years.

Ellis said Cabot was sailing with two friends Saturday afternoon, about 200 miles from the end of their long journey, when a rogue wave struck the yacht and swept Cabot into the sea.

Ellis said he had spoken to experienced sailors who described Cabot as “the most careful and responsible sailor that they ever met.”

“They are absolutely staggered that he could have been the victim of something like this,” Ellis said. “This was not some yahoo yachtsman out on a weekend jaunt.”

Rogue waves are extremely large and can seem to come out of nowhere, according to scientists who study the rare phenomenon.

Cabot and his two friends set out along the Newfoundland coast in winds that neared gale force Saturday morning, Ellis said, and the winds increased during the day. Ellis said that from what he understood, around midday, Cabot came on deck to relieve the helmsman. A wave struck with such force that the boat was knocked on its side, spilling Cabot and the helmsman into the water.

The helmsman was swept back onto the deck when the boat righted, but Cabot remained in the water. His friends unsuccessfully tried to get a rope to Cabot, Ellis said. The impact of the wave also broke a chain in the steering mechanism, so they could not steer the yacht toward him.

The Canadian Coast Guard began a search by helicopter, airplane, and boat that continued overnight, but they were unable to recover Cabot’s body until early Sunday morning. Cabot’s friends rigged an emergency tiller that allowed them to control the Cielita somewhat, and were able to bring the sloop into port, Ellis said.

In a statement released by the family, Cabot’s wife described the father of four as a man with a passion for adventure that he shared with others.

“He was good at everything he did, and a great teacher,” Betsy Washburn Cabot said in the statement. “You couldn’t get out of an invitation by claiming you didn’t know how to do it, because he would teach you how.”

Cabot wrote and spoke publicly about his voyages, and won a 2012 writing award from the Cruising Club of America, in which he was a longtime member. In addition to sailing, Cabot enjoyed skiing, whitewater kayaking, and horseback riding, family and friends said.

Cabot’s father, Thomas Dudley Cabot, served as director of the State Department’s Office of International Security Affairs under President Harry S. Truman. His grandfather, Godfrey Lowell Cabot, in 1882 founded the Cabot Corp., a Boston-based company that manufactures industrial materials.

Edmund Cabot was a surgeon at Brigham & Women’s Hospital for more than 25 years and taught at Harvard Medical School. He retired from medicine a decade ago and dedicated himself to philanthropy and sailing. He was the founder of Cabot-Wellington LLC and a trustee of the Cabot Family Charitable Trust and the Godfrey L. Cabot Family Association.