When undertaking training exercises, it should be remembered that enemy ships are actually manned by members of the Bundesmarine. Therefore, it is standard procedure to use un-armed torpedoes which emit a coloured dye, and set their pistol to impact and their depth to 3 meters under the target keel.
It is noted that members of the Bundesmarine can, and do, get a little bit narky when they are blown up by their own U-Boot Waffe.
Respectfully,
Lt. s. Z. Hans Gruber