Why 2 screws?

[Kapitan]

In correct the russian Delta IV and Typhoon's Oscars and remaining Yankees still use twin screw system, none have stern tubes but it does give redundancy if one is damaged, also because the vessels are so larger one screw just wouldnt propel the 48,000 tonne typhoon at 25knots.

the WWII era submarines were not built for silence untill the last part of the war when we began to understand the full idea and concept of submarines, which are stealthy undetectable platforms that should remain submerged constantly.

Also the hull shape of WWII submarines deny any possible use of a single screw nearly all of the submarines that use single screw configoration have an albacore shaped hull.

[Safe-Keeper]

Essentially a boat that goes under for short period of time. I makes a U, submerge down go forward suface up...U. Therefore, U-boat.

Not exactly, but perhaps you were joking.

[AVGWarhawk]

Originally Posted by Safe-Keeper

Not exactly, but perhaps you were joking.

HEHE!

[Kapitan]

also note the concept of using more than 4 blades on one screw would have been to risky and out of the ordinary even the first nukes like the novembers nautilus and seawolf all had 2 screws.