Here you go:
http://www.uboat.net/boats/patrols/patrol_4725.html
Note: this is an actual patrol as it happened IRL - of course, being a novelist, Buchheim has made some changes in his telling of the story, so "his" U96's route might be different. As noted above, Buchheim kept details like this deliberately vague, describing how it is to be a part of U-Boat crew rather than writing a war diary.