Just a couple of remarks:
1. There is an obvious reason for the KDB not being able to detect contacts on surface: being placed on deck, its sensors stickyied out of the water surface at that depth; it meant no reception at all. As for GHG and Balkon Gerat, they were basically the same device, and their sensors were mounted on each side of the boat's bow, near or below the keel. Due to their position, they were always submerged. Still, the interference created by waves made GHG's use model ponitless on surface, as its sensor were very sensitive to any source of noise, both internal or external. One of my sources (
http://www.cdvandt.org/GHG1996.pdf), reports a minimal depth of 20 m for a good hydrophone reception. On the other hand, the Balkon apparatus introduced several improvements:
- being mounted inside a special hull, below boat's keel, balcony hydrophones were maintained at a 2.5 m lower level and thus were less vulnerable to many sorts of hampering interference;
- Improved electronics and doubled number of sensor, made the new device ore sensitive and lesser subject to interference.
2.
At close range, the KDB had a better detection accuracy over the GHG . This was at the cost of an extremely reduced range and to an even more prononced susceptibility to noise sources. For the above reasons, the KDB was never used as a standalone device, but rather coupled with the GHG.
I ignore if the same can be done with SH5 upgrades. If not, KDB sensors settings should be tweaked to simulate the simultaneous use of a GHG, or selecting it as U-boat upgrade would be pointless.
