In my personal experience I saw far more carbon monoxide poisonings than injuries from explosions of gas engines. This is in 30 years of medical practice in a maritime community, and following many cruisers over a long peroid of time. Carbon monoxide is still a common cause of accidental death in boaters. The most common cause is "Teak surfing"--or other instances where a person is in the water near exhaust (main or genset). Another set of deaths is from boats where gensets are left running and the exhaust is going either into another boat (as in rafted up) or the gen exhaust is channeled from a wall where the boat is tied into an open window or port. As far as property damage: It is my impression that gasoline explosions and fires are far less than they were 40 or 50 years ago due to better safety controls. But all in all boat fires can cause massive property damage. But the biggest boat fire in our specific area was due to a flamiable substance in the engine room of a diesel vessel. Many are electical in origin. I am not personally adverse to gasoline as a propulsion fuel--and have owned both gas and diesel vessels. Bob Austin