The more natural answer would be that most are the result of some hull penetration. Obvious, I'm sure.Another 'spring chicken' here, doing research. Is it correct to assume the reason most of the boats sink are open seacocks?
Isn't that standard operating procedure? It is at our yard. Someone is down below, checking for ingress before she floats out of the lift bay.......And of course, unless the yard is crazy busy, you might tip the guys and ask them to just let it hang in the water for an extra five minutes before they pull the slings, just in case you find water coming in someplace.