Depends on how good you are at plotting
Ideally you want to be ahead of the convoy and just off to the side. The trick is to be out of the way of the lead escort, and once he crosses your bow, move in before the side escort comes up on your position.
Once your inside the screen, make your solution, fire your fish, and Dive right away.
Don't crash drive, that makes too much noise.
Don't wait for the fish to hit. You need time to get under.
Just shoot, and dive. After that... crawl under the convoy and hope for the best
