Inside the layer is the key, creep speed if you have the time, max no-cav if you don't, forget the periscope, you are hunting subs.
Also if you hear two or more active SB surrounding you; full stop until they start running out of battery.
Range detection against the Ohio is extremely short, no more than 20nm, you'll probably hear her escort first (anyone thought there wouldn't be one?) if you do, the boomer is near. Go to shallow depth, engage active sonar and go wild with SUBROCs.
If you do not receive the kill confirmation message search for her below the layer.
After the kill it's max no-cav inside the layer againg, keep it until you put something like 50nm from the kill point. Then creep all the way to the exit zone.
I was detected due to the active pinging but not identified (they where still searching for me at the kill zone when scenario ended), so I still got a major victory.