[Torplexed]

I think with any historical speculation you have to realize that nothing happens in a vacuum. If British intelligence ( some of the best, if not the best in the world ) picks ups that German shipyards are putting all their eggs in the U-Boat building basket, that means that Britain simply begins building more ASW escorts sooner. British shipbuilding capacity was always superior to German's and Germany only had so many specialized labor and shipyards for building U-Boats. As for the torpedo issue, the German (like the Americans) were already convinced they had the best engineered torpedo available at the start of hostilities. Sometimes it takes the strain of actual war to reveal the defects in any weapon system.

Besides, the beginning of the war would have been far to late to initiate such a program. Realistically you would have had to start sometime in the mid-1930s to gear up production and expand the crew training program to even have a shot at 300 U-Boats. And all this at the expense of the surface fleet which would have been difficult to do, since Admiral Raeder was running the navy then, not Admiral Doenitz.