[Armistead]

The game is not reality in many ways. Sonar works as good on the surface as it does dived, unless you're in a S class or using a mod that changes this. I think the only one that does some is Travs. As stated, even on the surface watch for clock lag. That simply means a group has entered into your contact zone. This lag will always happen regardless of your equipment of crew, but they usually don't pick up a contract, but you can. Get the lag, rotate sonar until you get a bearing and head that way. Just keep in mind a small group or a single often doesn't put enough load on your pc for you to notice lag and if you're not careful you'll find yourself getting shot at if you don't have radar.

I remained surfaced as much as possible unless in an area with too many planes. Try to hunt in straits or near harbor openings instead of the open ocean.