Investigators are trying to determine why a 1955 cabin cruiser blew up Saturday in Chesapeake Bay off Thomas Point, severely injuring a 73-year-old passenger and causing minor injuries to three others.
Domenic F. Angenelli of Washington, D.C., remained in serious condition yesterday at the University of Maryland Medical Center in Baltimore. Both of his ankles were broken in the explosion, which occurred about 1:20 p.m., and he suffered second- and third-degree burns on his arms and face.
The other passengers, who were swimming at the time of the explosion, were treated at the scene for minor burns and cuts.
Lt. Mark Williams, the senior investigator for the Coast Guard, said yesterday that the wooden boat had just been pulled out of the 35-foot-deep waters and that he was to examine the fuel lines for leaks last night.
Similar explosions have been caused by gas leaks and fumes accumulating in improperly ventilated bilges at the bottoms of boats, said Petty Officer 1st Class Tim Walker of the Coast Guard Search and Rescue branch.
If the engine backfires or there is a spark, he said, it could ignite the fumes and the boat could explode.
"It was an old boat," he said. "The new boats are designed to get rid of gas. Years ago, they were always blowing up."
Last year, seven people were injured in boat fires or explosions in 24 accidents in Maryland.
Under clear skies Saturday, the 34-foot wooden cabin cruiser, with four people on board, motored a half-mile southeast of Thomas Point to watch the start of the Annapolis-to-Newport yacht race. Mr. Angenelli was leaning back in a chair with his feet up on the engine when the blast collapsed the doors, causing him to fall into the compartment, said Darryl Claggett, a spokesman for Maryland Natural Resources Police.
He said there was no evidence that alcohol or drugs were involved in the accident.
Several boaters nearby witnessed the explosion.
Alan and Linda Adams, of Severna Park, helped all four victims out of the water within minutes.
They were transferred by Coast Guard boats to the Annapolis station, were Mr. Angenelli was flown by helicopter to the Maryland Shock Trauma Center in Baltimore.
The others were taken by ambulance to the Anne Arundel Medical Center.