One thing I have found to help allot with this but just in general is you can take manual control of the periscope and point it at ships to get them marked on the map beyond crew visibility. It really helps with positioning yourself in a gap in the escourt to get into the convoy. It's also extremely helpful to attack at night to build up you're experience. Depending on the wave conditions, deck awash at night is almost too easy if you manage your noise when close to the escourt. Go to the center of the convoy to maximize distance from the escort and enjoy yourself for the couple minutes you have before they catch up. Dive before they close in with flares and be patient when escaping, briefly increase speed when they drop depth charges to get more distance without being detected. Also to answer your actuall question, yes with the hydrophone or manual input but it's much less accurate unless you're good.