Tactics in May '43+

[rudewarrior]

I've seen many people quoting statistics that the majority of u-boat attacks occurred on the surface at night. I've read a few excellent books on the Atlantic war (including the Commander's Handbook), but nothing that gives a specific account of the tactics of attacking a convoy with full-blown radar or just later in the war for that matter. Is there anyone that could give me a brief description of attack doctrine/tactics in these situations? If you could quote a source, that would be even more helpful. Thanx in advance.