there is no minium or maximum altitude for bombs.
bombs must travel 1000 feet before they arm. if you are at 50 feet and going 500mph, the bombs will fall forward and it is possible form the to travel long enough to arm. that is how you can blow yourself up from the bomb blast.
as for information, i am guessing performance, or E6b, neither of wich i think exists for a PT boat. all other "boats" are just part of the terrain for lack of a better explination, there is no info for them.