[stephenf555]

(APOLOGIES, REALIZED THERE IS A THREAD FOR THESE HISTORIC-TYPE QUESTIONS. COULD A MODERATOR REMOVE THIS THANKS.)

Hi folks,
Reading an encyclopedic book on the uboots at the moment. I was reading about the Type XXI, which seems like the first sub to be designed similarly to today's modern subs.

It struck me that it was kind of weird that it took until this point (1943?) to design a sub with a hydrodynamically efficient exterior. I would assume that any naval engineer worth his spanner would know that all the protrusions and flooding outer hull would greatly affect underwater speed. I know that the earlier subs were designed to spend most of their time on the surface and to be able to submerge for attack etc, but it still amazes me that they were covered in so much equipment.

So, I guess I'm wondering is why it took so long for them to design a hydrodynamic sub? Was it an engine issue...that only then did they get appropriate electric motors and batteries capable of spending longer times under water? Or was it that the deck guns etc were becoming redundant later on in the war? Or was it simply that one day they noticed that is they got rid of all the extraneous stuff the boat would be much more efficient underwater...though as I said, I assume they knew this long before?