Speed and quiet - 1/3 vs 2/3 vs full stop

[Shadow]

Basically, you've to use the Signature Analysis panel to gauge just how detectable you are versus a specific contact. As long as you're not over 10 dB on any enemy sensor at a given speed, you should be safe.

However, it's a gamble to run above 2/3 speed unless you're more or less certain the enemy won't be detecting you (i.e. you're in their baffles), considering the faster you go, the deafer you are. That can make you lose contacts and prevent you from noticing (and adapting to) changing circumstances. Which can very well happen given escorts and submarines occasionally change course and/or slow down to listen in where they couldn't earlier.

Another thing to consider is that you can't measure yourself against what you haven't detected, so again, caution is advised unless you're fairly sure every enemy is accounted for.