Fissi

Given that it was always necessary for a U-boat to spend sufficient time on the surface to periodically charge batteries would not a radar have been usefull in detecting aircraft in the vicinity and determining how far away they were and in what direction they were located.?

The usual procedure when getting ready to charge batteries was to up-periscope and have a look around. If nothing was in sight to surface and station lookouts who stayed on station to spot aircraft throughout the battery charging procedure which took several hours. Depending on cloud conditions it was not always possible for a lookout to spot an incoming aircraft in time to avoid an attack.

The installation of the passive radar detectors like Metox and some others only served to complicate matters. The problem was that the passive radar detector could detect an aircrafts radar at ranges far greater than the range at which the aircrafts radar could detect the submarine. Without getting into too much detail this was because the Metox was dealing only with a one-way propagation loss while the aircraft radar had to deal with a two-way propagation loss plus the additional factor of radar target strength of the submarine. The result was that Metox alerted the submarine when the aircraft was at a distance at which it could not see the submarine on his radar. Since no range information was available from the Metox the submarine commander had little choice but to break off battery charging and dive with an uncharged battery. During the course of a nights operation this scenario could be repeated over and over if there were aircraft searching, forcing the submarine to dive, many times quite needlesly, and foregoing the needed battery charge.

Might not a radar on the submarine have helped? The radar would not only have indicated an aircrafts presence, even in the dangerous situation of low cloud cover when lookouts could not see an aircraft, but would also have given the commander some information as to the Aircrafts range and position and whether the aircraft was moving away from or toward the submarine. It would seem this would have been extremely valuable information for the commander to have and might have eliminated many needless dives interfering with battery charging operations.

Don B