External torp transfer
 

maybe im thinking of the wrong subs but didnt the type VII have a way to transfer from the rear stores to the front of the sub via a track on the deck?

not that i know of ?

I've seen pics of it being done. They are on this web site somewhere. The crew used floats to shuttle the torps from one end of the ship to another,
it took forever and was dangerous. I do not think it was a common practice at all. Plus the water had to be calm, and crew had to get into the water,
so doing it in the north Atlantic would be a very very bad idea.

I think that the only reason I would ever do it is if one set of tubes ( forward or aft ) were destroyed and absolutely had to reload the other set.