As has been stated, in WW2 many ships and smaller craft were sunk by the shock waves and splinters of HE ordinace exploding nearby. The effect of a 500lb or 1000lb bomb exploding nearby the WOODEN hull of a PT boat going at full speed would be catastrophic.
As a PT boat driver, I think the model is fine - if not slightly in our favor. Watch the gun sight cams of B25s strafing and bombing Japanese destroyers and Patrol Boats some time. OUCH!
- Andy