Not going to your patrol grid

[Abd_von_Mumit]

Originally Posted by Tobus

Well, going under isn't going to save you fuel. This because the diesels burn plenty more fuel to get the batteries full again. After surfacing and setting speed to 8 kts means your engines burn fuel at about a normal speed of 12 kts to both power the boat and charge the batteries.

As far as I know charging batteries doesn't consume any diesel fuel at all IN THE GAME. It's unrealistic, but probably not moddable (someone would have fixed it if it was).

Optimum speed for VIIb type is 8.25 knots and after upgrading with GW Kapselgeblase it's 8.5 knots. The value is different for other types of boats.