Hi Keith,

Both of those types of radar were used on the Type XXI but the type XXI was not deployed in numbers during the war. Many were built but the war ended before they were used operationally in combat. Those U-boats (Type VII & IX) with models through FuMO-61 Hohentwiel were deployed but I don’t know how successful they were.

Late in the war U-boats had to stay submerged most of the time because the Allies owned the air. If they were detected on the surface, they had to stay on the surface and fight with their anti-aircraft guns which frequently weren’t effective. Even diving wouldn’t guarantee their safety with the development of FIDO (an acoustic homing device). Once a U-boat was spotted by a plane the FIDO could be dropped in the swell left by a U-boat that had just dived and it would home on the noise from the props as the U-boat tried desperately to get away.

The schnorchel was probably the U-boat’s best defense against the airplane as it kept the U-boat from having to surface at all. However, allied radar was eventually developed to the point where it could detect the schnorchel of a submerged U-boat at quite a distance.

U-boats did deploy radar detectors with varying degrees of success during the war. They also deployed radar decoys. One type was carried aloft by a hydrogen-filled balloon and another was attached to a float.

As with all weapons used during the war, it was a constant game of leapfrog. Develop a new weapon & the other side developed a counter measure. Then you had to develop something to circumvent the countermeasure etc. As the war progressed, fewer and fewer U-boats came back from patrol until it became almost suicidal to go out on patrol.

Regards,

Ken Dunn