Notes on the Type XXI

[Marcello]

Current Order No. 63 of November 43

Procedure for T V torpedoes

1) The increasingly strong defence of the enemy, compels us to take full advantage and make a success of every opportunity of firing which occurs, even when take by surprise. The TV is the weapon, qualified to make the U-boat the dangerous attacker and not the hunted, even in the case of clashes with the enemy.

Since in the Iceland channel up to 20° West and in the Bay of Biscay to 2° West, anti-submarine surface patrols are mainly to be reckoned with, cruises through the maritime area are to be made with as many T 5's as possible in the tubes.

2) At night carry continually one bow and one stern tube, with T 5 if possible, ready to fire. That is to say: flood tubes, bow cap open.

[...]

3) With unexpected targets, one should fire over the netcutter with positions between 20-160° ahead over the cam.

N.B. In case our own U-boats should be operating in the same area, it must be remembered that firing is forbidden against U-boats unless definitely identified as the enemy.

[Marcello]

Current Order No. 64 of October 1944

Procedure for firing Lut torpedoes in unexpected combat

Emergency setting T IIIa - Lut I

1) The current order no. 6 contains instructions for immediate firing of a turning torpedo (without director angle computer) in unexpected combat

2) On the sudden approach of destroyers, after firing a "Zaunkönig (Wren) torpedo in defence, naval operation T IIIa Lut I offers the further possibility of the use of torpedoes.

3) Emergency setting T IIIa - Lut I -

Loop: Short, V - Lut (TorpedoFitting): 11 nautical miles

Track 180, Preliminary run: 500

Firing angle: 0 or 180, Gyro-spindle: engaged

Depth 4 meters, Tubes: secured

4) With this fine adjustment, immediate torpedo track can be launched against the enemy, only, however, in position 0 to 5 degrees - and with enemy speed 15 at distance of 1000 to 2000 metres and 20 at 1000 to 3000 metres. Parallax should not be considered.

5) In other positions or with greater distances "Lut" firing procedure should be followed (Firing with a director angle computer)

[...]

7) In firing "Lut" torpedoes, tube No. II primarily, in the 4-fan tube mounting (if not set for firing turning-torpedoes) secondly tube No. III, should be used, in order to have available the 3-fans I, II, and IV or the 2-fans I and IV (with V-Lut and deviation on preliminary firing)

[...]

9) The recommendation in Current Order No. 42 that "Lut" torpedoes should should be used in cases where the enemy is suspected of using anti-T V defence, in the form of immediate readiness of T V and "Lut", i.e. if occasion arises, the tube loaded with a "Lut" torpedo should be open and ready for firing, instead of the tube loaded with TV

[Marcello]

Type XXI trials footage

U-2513 using the snorkel



U-2513 in a crash dive