Work out how long at your speed (9.5knots) will it take to get to your waypoint.
Make notes with supermarks
Draw legs and set headings to your patrol area. "Auto fix" will keep posting your position on the map.
You can click on the stopwatch to get an alarm clock that TDW added. This can be set to alarm when your timed legs runs are up.
As you get closer to patrol area, start using "No Station Search for Real Nav" You must go below to use as the boat will auto dive.
When you start hunting your area, switch to " At Station Search"
Sink lots of ships