[derstosstrupp]

Here are the myriad orders, particularly early war, with regard to detonator settings, as Germany struggled to reconcile the various torpedo problems. Not for the faint of heart!

Source is “Wolves Without Teeth: The German Torpedo Crisis in World War Two“ by David Habersham Wright.

MZ = magnetic detonator (“Magnetzünder”)
AZ = impact detonator (“Aufschlagzünder”)

At patrol start:
- Before Oct. 2 1939, your pistols are either set to MZ or AZ and cannot be changed during patrol. Randomly determine what eels are set to what. It was however possible to swap out pistols between torpedoes, so keep that in mind.

- After that date, decide when loading each eel into a tube what you want the setting to be (keeping the standing pistol orders in mind). No switching during attack!

- Roughly 75% of all torpedoes fired were G7e. This was the standard torpedo of the war, and cheaper to produce. Use a random number generator or dice to determine the type of each torpedo you get, 75% chance of each being G7e up to the following limits. For Type VIIB or C, you can load max 9 G7e (all tubes loaded with G7e, and 4 in bow internal storage). For VIIA, max 8 (bow tubes loaded with G7e, and 4 in bow internal storage). Unmentioned slots of course get G7a.

War start:
Torpedoes had the Pi1 pistol and had either MZ or AZ preset, which could not be changed during patrol (unless the pistols themselves were swapped between torpedoes). Leadership put its faith in MZ, so this was preferred due to the devastating results of exploding under the target’s keel. No limit on MZ use at this time.

Sept. 15, ’39:
For targets < 3,000 tons, use only AZ. Larger targets have a greater magnetic field sufficient to detonate the warhead.

Sept. 17, ’39:
Premature detonations continue. BdU forbids MZ. Use only AZ. Note that, since pistol settings could not be changed during patrol, these are odd orders, likely born of Dönitz’s frustration.

Oct. 2, ’39:
“Schalterstellung A” (switch position A) introduced, allowing the pistol settings to be switched on patrol between MZ and AZ, allowing the mandatory AZ setting to be set. [boats at sea during this time will be fitted with torpedoes with this on next patrol]

Oct. 11, ’39:
The torpedo inspectorate recommends a new cable layout in the torpedoes, and BdU allows MZ use again. [boats at sea during this time will be fitted with torpedoes with this on next patrol]

Oct. 18, ’39:
BdU forbids MZ again after U-46 reports multiple premature detonations.

Nov. 1, ’39:
Set depth 2 meters shallower than target draft due to deep-running torpedoes, but no shallower than 3 meters (4 in strong Atlantic waves). Finishing shots on stopped steamers depth setting 3 meters.

Nov. 8, ’39:
New pistol Pi a+b created with a reworked MZ detonator. Dönitz allows MZ firing again, but not with the G7a “fast” setting of 44 kn. Depth for MZ to be draft + 1 meter. [boats at sea during this time will be fitted with torpedoes with this on next patrol]

Jan. 18, ’40:
Targets < 4,000 tons use depth setting of 4 meters. All other targets use ship’s draft + 1 meter.

Mar. 19, ’40:
G7a fast setting of 44 kn forbidden. Only AZ setting allowed in cases where the boat absolutely must remain hidden. If boat’s position becomes compromised, OK to use MZ (as the consequence of premature detonation is not so dangerous then). Minimum torpedo run of 500 meters with MZ. Separate multiple shots by 9 seconds. Set depth 4 meters for all targets < 4,000 tons and destroyers.

Apr. 11, ’40 (for boats in Norway campaign):
Keep forward tubes ready with 3 eels set to AZ and one to MZ. Attacks against large targets are to be with AZ, depth setting 2 meters.

Apr. 18, ’40:
Norway campaign boats no longer use AZ except in narrow fjords. With MZ, set depth equal to draft, 4 meters against destroyers, 3-4 meters against submarines. With AZ, set 4 meters, 3 meters in good weather.

Apr. 21, ‘40:
MZ shots depth target draft + 1 meter. Against destroyers, subs, and steamers under 4,000 tons, set 3 meters in bad weather, 2 meters in good. For AZ, 3 meters against all targets, 2 meters in good weather. Against capital ships, when firing AZ, set depth 5 meters.

Jun. 1, ‘40:
MZ firing forbidden (would remain so until late 1942).

Jun. 20, ‘40:
G7a fast setting of 44 kn again permitted. Depth to be set as draft minus 3 meters (2 meters in excellent weather).

Jul. 30, ‘40:
G7a fast setting again banned. The need for higher torpedo production meant that improved torpedo engines could not be installed.

Nov. ‘42 (in Med) or Dec. ‘42 (in Atlantic):
The Pi2 pistol is introduced, correcting the MZ problem. [boats deploying to these areas after these dates are assumed to have the new pistol]