Subs

The player has a disadvantage when underwater, the escorts come after you from the beginning, even if you're quiet. The first detection from passive sonar is that from range, they then pivot the hydrophones until they get a bearing. Once they arrive, its now active pinging. It means that the pinging will help set the dc and confirm the location of the enemy sub. If you ping all the time, you will never suprise a sub. Low frequency is detectable from very long distances. If the ship is going too fast, the engine will drown out the sub's noise. That is the way it works when you are the hunter, you get a distant reading and when you arrive at the site, you either wait or depth charge.

What I do is to wait to the side because it avoids having to deal with the gun behind the conning tower, and he can't launch a torpedo at you.

If I am beside the sub, I only have to launch fewer dc from only one side. You should be able to hear the flooding or discharge of the ballast tanks.

The best way to dc a sub seems to be that of deep to shallow with the vessel getting out of the way before launching shallow. If you disperse your dc, you end up running out in no time. Since the game is command oriented, if you are part of a group, the commander should at least configure the approach, namely all abreast, 3 charging while one monitors, etc.,...

While we are talking formations, the few convoy actions I have seen shows that the escorts come at you in a gaggle, the convoy is not organized.

Knowing that the escorts are coming after me makes me try to orient myself before they arrive, waiting until they get within 1km is enough to dive in time. I can either shoot them or if possible, get perpendicular to their track so that when they drop their dc's I can get out of the way. I can then pivot turn while the come around again.