The “Mehrfachschuss”:
One of the three types of firing (besides single shots and fans) was the “Mehrfachschuss”, or multiple shot. This type is very little known, and so if you want to use it the way the Germans used it, I will lay it out. In the game it is easy enough to just shift the point of aim to different parts of the target in rapid succession, but if you want to simulate how a shot like this was done in real life, here it is. This differed from “Einzelschüsse”, which were single shots that were individually aimed at separate targets.
You can see mention of this both in the commander’s handbook (1) as well as the British report on the captured U-570 (2):
(1)
“171. To the extent sufficient torpedoes are still available, multiple shots (double or triple shots) should be used against valuable targets, even if at close range and with reliable shooting data. All shots should then hit, the purpose being to destroy the enemy with certainty. In doing this, the shots should be fired by shifting the aiming point on the target.”
(2)
How -
The gist of it is you fire what is effectively a longitudinal spread, either two or three torpedoes all on the same bearing, at intervals of 8 seconds. This interval insured that torpedoes did not interfere with each other when firing MZ and also made it easier on the man at the firing switch box in the control room.
For a Mehrfachschuss of 2:
You take the target speed and multiply it by 2, and then shift your aim point that many meters forward of target center. Fire, wait 8 seconds on same bearing, fire again.
As an example, say the target is going 16 kn. In 8 seconds that target will travel about 65 m. You take 16×2, which is 32, so shift your aim point 32 m forward of the target’s center. You fire, and by the time the 8 seconds are up and you fire the next torpedo, your aim point should be somewhere in the aft half of the target, providing a nice forward/aft dispersion so both hit.
For a Mehrfachschuss of 3:
Same as above however you would just multiply the target speed by 4. In the example above, you would have shifted your aim point about 64 m forward, and so in 8 more seconds, your aim point is then center mass for the second torpedo, and then aft for the third.
The Germans used this for firing on good data when they wanted all two or three torpedoes to hit to ensure sinking. They used fans (“spreads”) to ensure one hit (on bad data), as the handbook lays out.