External Reloads

[AntEater]

It takes just about forever (100 mins ONE torp!).
But in SH3 you're still much better of than in reality.
In reality the crew had to surface (obviously), remove the deck gratings covering the storage tube, open it (sometimes pressure build up in those cannisters and at least one crewman was killed when he was struck in the head by the lid of the cannister), rig up a small crane, carry it forward or backward to the torpedo loading hatch, which had to be equippec internally and externally with a slide, halyards and so on and slide it down to the torpedo room.
Only there it would be examined and fuelled.
It was impossible to dive in such a situation, not a comfortable situation for a submarine, as there were over a dozen additional men topsides and the loading hatch could not be opened and closed as easily as the tower hatch.
So if you want to play it realistic, wait until nightfall in totally calm seas and do not dive whatever happens.
For obvious reasons, only ATOs (air propelled torpedoes) could be carried topsides, not ETOs (electrics).
A ATO without fuel is practically dead iron which can be stored infinetely, it was only fuelled inside the sub, while an ETO contains a lot of chemicals in the batteries which have to be checked and refilled all the time, and the batteries have to be heated in order to work.
So only use T-1s in external storage. IXs normally carried only ETOs (T-2, T-3) inside and ATOs (T-1) external.
I'm not sure how to handle FATs based on ATOs though, maybe their machinery was too delicate to be left without maintenance.