By 1941 there were 29 total PT’s total in the US Navy, by December ’43 there were 29 squadrons. Indeed, by the end of the war the small ships, PT’s LCI etc. numbered 7,000 craft of 80 types. Many Early PT boats had up to 4 torpedoes and 2 twin .50 Cal guns in powered mounting, a heavy load for the day. As with most American hardware, this was only the start! Soon a 20mm was added at the stern as standard, useful for surface or air action. Then, enterprising crews frustrated by strafing the tough Japanese barges to negligible effect mounted a USAAF 37mm automatic gun (acquired from an Air Cobra) and found it most effective!
Indeed, America had not been blind to the possibilities of the coming war and took great pains to watch and learn from her allies and foes so that when war came, America was ready to put into place a building program that dwarfed all the other navies combined and led to the naval dominance that she still enjoys today.