Hi Rainer:

1. My guess is that. in genera, a freshly deguassed boat would exhibit a reduced detectability (detection range). But the answer is difficult because we also have to consider the boats heading and latitude. If we could stand off at a fixed position and measure the total moment of a stationary submarine as it is rotated horizontaly about a central vertical axis we would also see a great variation in the \"induced\" magnetic moment with the maximum tending to occur with the boat near a north-south alignement and a minum on an east-west alignement. Also the \"induced\" moment tends to be reduced in far northerly (or far southerly) latitudes where the earths magnetic lines become more vertical. Also we must remember that even under the most optimum conditions the detection range was never very great. It is kind of like saying that the range might be reduced from say 600 yds to 400 yds - would that really make much difference? I don\'t think MAD was ever a very important factor in the submarine war during WWII. It was confused a lot by ships on the bottom and even some geographical features, and a lot of time had to be spent trying to determine what it had detected even when a detection did occurr. I can\'t think of any submarines sunk solely on the basis of a MAD detection. Maybe someone can shed some further light on this point.

2. I am not aware of any tests of MAD gear to determine the effect of de-guassing on the detection range - but that is not to say there was none. It is just that I never came across anything that would indicate such tests had been done.

Don