Tide Atlas(s) were issued to U Boats. Imagine using the current (even a rip current) to your advantage to slip through a defended channel or not fetch up in shallow water at low tide. Just depth sounding in a port is not enough. You just may hit "hard water" with the bow while the sounder is telling you 10M under the keel.
S'PC
__________________
DID, no cheats, no shortcuts, no non-historic equipment deviations. Boat and crew safety is integral with my immersion style! Follow the historic events during your patrol:
http://www.uboat.net/today.html