[scrag]

At the start of the war US and Japan envisioned submarines acting as long range scouts. The US termed there boats as "Fleet Boats". When the Balloon went up and bulk of the American Fleet was OOA for the first year it forced a change of tactics - this also lead to a mindset change and a more dangerous operating profile - the rest is now history but essentially the book was being re-written by the like of Dealy, Morton and Ramage.... They did loosley adapt some of the U Boat Tactics but the single biggest factor in US operational success was likely Radar. This allowed the US Subs to see A/C sooner, to conduct approaches in a number of poor conditions and to even communicate with other US Subs with the Radar (read "Clear the Bridge" by Okane)

Conversely the IJN used the submarines or better stated squandered them by forcing them to resupply troops, Scout for US Warships, to essentially severly limit there use against any Allied Shipping (the exception here would be the operations by IBoats in the Indian Ocean, which enjoyed some success) and finally to serve as Kaitan platforms. I Boats also continually fell victum to Radar and were frequently sunk (eventually the US learned how to fire the guns and use the radar as Fire Control radar). The Japanese ASW forces erroneous believed that US Subs operated at a shallower depth and so the US Boats were able to safely evade deep. IJN Subs did have a superior torpedo just stupid tactics. Why - as great of an Admiral that Yamamoto was he was a Carrier/BB Admiral and by comparisson we have Nimitz???? A Submarineer.

The Germans - masters at some craft but frankly amazing stupid in others (lack of radar or any means to detect it even after sufficent evidence was accumulated to prove conclusively it existed) Enigma compromise, insufficent numbers of boats. etc The dive times were very quick by western standards but again the threat was all around where as the Pacific not so much.