How Did the U-Boats Find Targets

[bill clarke]

Ok guys this may sound silly, but in the game we get a red icon to signify a enemy contact, but in reality how did the u-baots fins their victims ?

[Khayman]

Patrol lines of U-Boats along presumed Convoy courses. First one to spot a convoy would home in other boats. Codebreaking and other intelligence. Guesswork. Sometimes the Luftwaffe, but their position reports were frequently found to be so inaccurate as to be virtually useless.

[tbarak]

I read too that they used a kind of dragnet technique, where the boats spread out abreast with maybe 50 miles between them and they "swept" the sea. Much like how fowl hunters walk abreast through the bushes to flush game birds. Only problem was I think maximum visibility is maybe 15 miles so there were always holes in their line of sight. It was in all reality a pathetically hit and miss operation with too few boats and ineffective tactics.

[runyan99]

In short, they picked a good spot, and then got lucky.

Originally Posted by runyan99

In short, they picked a good spot, and then got lucky.

Bingo!!!

[Khayman]

Originally Posted by runyan99

In short, they picked a good spot, and then got lucky.

I think that's underestimating the German code-breaking efforts. A lot is said of the breaking of Enigma, but the Germans had their successes as well. Frequently the patrol line was placed on a known route rather than one that was guessed at. You could say it would then be very unlucky if no U-Boat made contact.

[Puster Bill]

Originally Posted by Khayman

I think that's underestimating the German code-breaking efforts. A lot is said of the breaking of Enigma, but the Germans had their successes as well. Frequently the patrol line was placed on a known route rather than one that was guessed at. You could say it would then be very unlucky if no U-Boat made contact.

This is true. During early 1942, when the British were reading the 3 rotor Naval Enigma fairly well, they were able to route their convoys such that only 1 in 10 convoys were discovered by u-boats. When the 4 rotor Enigma came in, the Germans found 1 in 3 convoys. That is because they had been reading the British codes. In fact, Wilhelm Tranow's Beobachtungsdienst ("Observation Service", usually shortened to B-Dienst) had been reading British Naval and Merchant Marine codes since the beginning of the War. They were able to read the two main English systems up until about mid 1943 - early 1944. The Allies changed their codes due to definite proof from intercepts of messages to the U-Boats that the Germans had cracked their codes and were routing them to intercept convoys and individual ships.

The British actually knew, or at least suspected, that this was the case for quite some time (in fact, some of the highest level users of the British 'Naval Cypher', which was really a codebook, got the only unbreakable system to superencipher it, the one time pad), but it takes time to compile and distribute a system. You need everyone to start using it at the same time, otherwise you will compromise the new system by having similar or identical messages in both the old and new systems.

The final word must go to Karl Doenitz on the effectiveness of B-Dienst: He said they supplied fully half of the intelligence used by the Kriegsmarine.

By Contact Reports of Convoys, and then the old trusty Eyeballs for others.

[Khayman]

Originally Posted by Magua

By Contact Reports of Convoys, and then the old trusty Eyeballs for others.

But where did the contact reports come from?

[Heibges]

The S.O.P for a patrol would be to stay on the surface and conserve as much fuel as possible. Soundchecks were conducted at dawn and dusk, so the uboat wouldn't be surprised in the rapidly changing visibility conditions.

I heavy fog, and conditions of extremely poor visibility, uboats stayed submerged because the danger of being rammed was greatly iincreased.

Airborne radar caused the the uboats to have to recharge batteries at night and attack submerged during the day. Their great successes had been mostly based on the highly mobile nighttime surface attack.

After Black May, uboats were increasingly forced to stay submerged for up to and including the entire patrol. This was accomplished through use of the snorkel. Due to its low underwater speed, the only way a uboat could intercept a target now, was if it steamed right over it. Also, by this time, uboats spent much more of their time going to and from port rather than patrolling for the same reason.

During the good years, to intercept a convoy they would set up a patrol line in the convoys path. They would move toward the convoy at low speed. If they got to a point where they should have intecepted the convoy, but hadn't, they turn around and follow a reverse course at hight speed, then start the process again. The first uboat to spot the convoy became the contact holder and would broadcast updates every hour. If a contact holder stopped broadcasting, another boat was expected to take over as contact holder. Keep in mind, uboats did not conduct "coordinated attacks" on convoys in the tradional military sense in the word.