111. Intermittent sonar setting, in addition to always on and always off.
We know that ASDIC could only be successfully operated when the returning signal wasn't swamped by engine noise, meaning that it was only of use when "looking" ahead roughly 45 degrees either side of the escort's bow, and below a top speed of circa 18 kts. It's effectiveness was likewise diminished in rough seas.
For our purposes, this means that Bitterns and Corvettes would be able to use ASDIC most of the time, but Tribals could not, if above 18 kts in speed.
This would allow an intermediate setting between "always on" and "always off" whereby the Bitterns and Corvettes were (ASDIC) always on, but the Tribals were only periodically on, if any escort made a hydrophone contact, or, a visual one (which then submerged). Further complexity to added if idea #110 was simulataneously implemented, whereby the Tribals tended to range further away than the other two types (at 36 kts), from their "home" position in relation to the convoy, then searching an area with ASDIC at 18 kts, before racing back at 36 kts to their "home" position. This behaviour would make approaching the convoy with a Tribal between you, and it, more dangerous both surfaced or submerged, as the former could rapidly erode the "safe" distance away from escorts detection at night, or catch the u-boat submerged during the periodic ASDIC phase...
As a lobby-setting (preferably a concealable setting), this would again make the distribution of particular escorts something to take into consideration both in daylight and at night, when approaching a convoy...
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