It seems to me that the weapon loadouts are, for the most part, fine. The 37mm seems like it could use a few reloads, though. I don't know how many rounds were carried in a 20mm mag so can't comment on that.
As for damage, remember that these are wooden boats with most the crew exposed to attacks from above, and having 150-200 cannon rounds and a few hundred MG rounds impact on you, plus the splinters, will ruin anyone's day. If anything the guns are actually overmodelled, a few shots of .30 caliber should be able to kill all the gun crews and disable the boat (kill the helmsman).
IMHO, the PT is fine, and we're all just used to ostwind-like vehicles - forcefield-covered open tops with 3 feet of armor compressed into a few centimeters.
[This message has been edited by Specterx (edited 02-06-2001).]