The ranges are affected by a long list of factors, though the exact amounts are unknown due to the lack of documentation.
One thing you should avoid is calm (glass) seas, anything below 2 m/s wind and they can pick Bernard peeing on the head....
Also try instead of a 180º headon approach a 45º angle between the lead and side escorts untill you're inside and then tun to 90º to attack, also plot the lead escort zig zag pattern to try to get inside while it's on the other side of the convoy, sounds difficult, but once you're used to it you don't even have to calculate it.
Once inside I personally I use a chicken tactic, choose two good targets, shoot a couple of eels at each, then dive as quickly as I can to at least 90m and run away, then If nobody follows plot a new intercept course to hit again, don't stay to see the fireworks, it gives your opponents the time to detect you.
Ref
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