Question On Tactics

[banjo]

I took some minor critisizm in a previous thread for my tactic of sinking all the escorts and then the merchants. This tactic was deemed 'unrealistic'. Probably true in RL but works like a charm in this game. I routinely sink all the ships in a convoy. I am awarded MOH after MOH and sink dozens of tons on most patrols, all without having a single depth charge dropped on me (with one exception--see other thread). However, it has become kind of routine now.
My problem is I am always, always detected by the escorts. Even tho I turn radar off as soon as I have determined convoy course, and even tho I submerge miles ahead of the convoy, way ahead of any visual contact, and even tho I lie silent with periscope down, tracking the convoy by sound, and even tho I park 2000 yards outside of the path on the nearest escort, I am always detected. Hence my tactic. I never have any choice.
So--my question--how do some of you other experienced skippers get close enough to sink some ships and yet not get detected, particularly late in the war?

Thanks.

I am playing TM 1.6.4