[Red Devil]

I was at 100 feet depth, so certainly zero visuals. Thanks for all the above info, very interesting. I can attack a convoy with relative ease, getting inside the destroyer screens, but even then some merchants will suddenly change course and the convoy becomes haphazard. But not all the time. Maybe as it was stated, 1943 saw a turning point where sonar is on merchants but I have never been pinged by a merchant so it must be passive. I have been pinged by destroyers quite a lot. Tactics in a convoy dictate a quick attack, on at least 2 vessels, go deep, change course to that which the convoy was originally going, and once deep, (300-320) stay at slow, if rough weather, go to standard for as long as I can, leaving enough battery power to make an eventual escape, hopefully the convoy will begin to converge again, and I am waiting. The destroyers for some reason think I am still behind the convoy and continue search patterns. It works. Single shipping or pairs, no destroyers (unless liners) and it seems to be harder. Talking of liners, they do not take evasive action when I am sneaking in. I am at 300+ when the lead destroyers goes past, coming up to P depth after he has passed. No fast than 1/3 at this stage. I dont know if its in the game, but its a fact that Asdic ( sonar) was terrible in rough weather, almost 100% useless.