When you initially get the observation and take bearing and turn on course, might be worthwhile to drop down and try to get a range approximation from the sonar guy. Problem with this is it slows your interception and u may lose the contact. The way I try is an aggressive burst towards that contact. Watch the direction his bearing is going and follow it or put ur course left or right of it, e.g his bearing has been drawing left 090, 085, 080 at each observation then I would steer maybe 060 and go to flank/full between observations. Same if bearing is drawing right e.g 090, 095, 100 then I would steer maybe 130. If after a period of time I am not any closer e.g 45 mins to 1 hour then I would probably give up as I am just wasting valuable fuel on a fast moving contact that may kill me or be able to outmanoeuvre a long range torpedo shot. I note where I came across the fast mover especially if I think its a fast moving high value target and may check this area out again in a future patrol to see if I have better luck. Happy hunting
