This thread orignally raised the question... (Yes, a bit of thread necro... )
Let me counter the usual.
More U-boats is an obvious non-starter. The Brits will never go for it.
Better fuel economy is problematic. (Diesels are pretty efficient, & carrying more fuel is a space issue.)
More time on station actually isn't beneficial. Getting to the patrol station faster, or reducing turnaround time between patrols, is. Reducing the refit time safely is problematic, given the experience with Scorpion.
That being so, faster U-boats is a good idea, & more powerful engines can be developed fairly covertly. Moreover, they have uses as railway engines, so there's an obvious excuse. So, a somewhat bigger U-boat (nearer a Type IX, to be able to reach the U.S.) that's also faster would be roughly ideal.
More torpedoes isn't, necessarily, a good thing.
Better torpedoes do require better testing prewar (not necessarily hindsight...). Larger warheads, able to sink ships with single shots, would be good. Better firecontrol gear, able to ensure more hits as a percentage of shots fired, would definitely help. (AIUI, German wartime gear was pretty crude by U.S. standards, & even then, the U.S. doctrine was spreads of three.)
Increased use of submarine-laid mines, especially in the period when German torpedoes were problematic, would be good. Developing a better sub-laid mine, especially a magnetic mine, would be a good idea.
Developing a method to track convoys by their TBS emissions would be an excellent idea.
I'll leave off the schnornchel & electroboot ideas; they both seem to demand wartime experience with Allied ASW.
Did I miss anything?
If the Germans want to sink more shipping, they can either:
- Increase the number of U-boats (more pre-war production, better survivability, or give U-boat construction priority during the war)
- Increase U-boat time on patrol (better fuel economy, bigger fuel tanks, or underway replenishment)
- Increase tonnage sunk per U-boat per day at sea (OTL this number was about 750 tons. The Germans could increase this number by fixing their torpedoes during the opening months if the war, or by using effective air reconnaissance to vector U-boats towards ships, instead of U-boats having to make a picket line and hope to stumble on a ship)
- Increase the tonnage sunk through other means (mines, aircraft, surface raiders, etc) I have no clue how to do this.
Let me counter the usual.
More U-boats is an obvious non-starter. The Brits will never go for it.
Better fuel economy is problematic. (Diesels are pretty efficient, & carrying more fuel is a space issue.)
More time on station actually isn't beneficial. Getting to the patrol station faster, or reducing turnaround time between patrols, is. Reducing the refit time safely is problematic, given the experience with Scorpion.
That being so, faster U-boats is a good idea, & more powerful engines can be developed fairly covertly. Moreover, they have uses as railway engines, so there's an obvious excuse. So, a somewhat bigger U-boat (nearer a Type IX, to be able to reach the U.S.) that's also faster would be roughly ideal.
More torpedoes isn't, necessarily, a good thing.
Better torpedoes do require better testing prewar (not necessarily hindsight...). Larger warheads, able to sink ships with single shots, would be good. Better firecontrol gear, able to ensure more hits as a percentage of shots fired, would definitely help. (AIUI, German wartime gear was pretty crude by U.S. standards, & even then, the U.S. doctrine was spreads of three.)
Increased use of submarine-laid mines, especially in the period when German torpedoes were problematic, would be good. Developing a better sub-laid mine, especially a magnetic mine, would be a good idea.
Developing a method to track convoys by their TBS emissions would be an excellent idea.
I'll leave off the schnornchel & electroboot ideas; they both seem to demand wartime experience with Allied ASW.
Did I miss anything?