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Old 06-18-2020, 07:54 AM   #10
Catfish
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First, i have to admit i still have not played, but i will
As far as i read and followed the development, thermal layers have not been modelled yet.

Regarding ASDIC, from witness reports to what i read over decades i have some doubts about the accuracy and general effectiveness of ASDIC, at least until very late in the war. It is right that the systems got better over time, but most of escorts had an early type 141 or earlier on board, if at all. A lot of escorts did not have installed any.

Also it is unlikely to find a boat via ASDIC at periscope depth, for the same reason it could not be detected by it when surfaced. The ASDIC's detection cone for shallow swimming objects only works in very "special" environments, and mostly not even in completely calm seas. In most of the 50ies books about submarine detection this is still described as a big problem.
When waves are reflected from the ocean floor at shallow depths it is more likely, also a thermal layer can reflect upwards to meet a U-boat hull, and then being reflected back by already becoming inaccurate.
So even if the DE is lucky and gets a reflection from a certain direction, the real depth and distance are impossible to measure. If you think of atlantic waves and the general disturbance in the upper water column the chances for detection are small, to say at least. This has been modelled in some of the real old simulations.


If a boat still had been detected by active ASDIC at low depth, the contact would be gone by a distance of appx. 400 meters, from then on the DE would have to race to the last point of detection, guess where the boat turned to and at what speed, and also guess its depth.
Listening devices and ASDIC would also not work at higher speeds of course (which is why hedgehog and squid had been developed).
The DE also had to be quick to not become a victim of its own depth charge explosions.

The tactics and methods can be read quite accurately in C.S. Forester's "The good shepherd", though even this is highly optimistic for the time it is supposed to happen.

To make it short i doubt a boat at perisope depth could be detected by ASDIC in most circumstances . If anyone finds a good report on that, i would like to read it.
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