I've been biting my tongue for two days now, trying hard not to say "Guess what? Guess what?" This is the answer to my dreams. No more dumping torpedoes (it didn't occur to me until just now to remove them while in port). No more reminding myself not to go faster than 17 knots. WOO-HOO!
I tested it several times. The cruise speed at 2/3 is only about 7 knots, but when I manually set it for ten, waited a few minutes and checked the maximum range at that speed, and every time it was just a hair over 10,000 km. I checked
www.uboat.net and a couple of books, and they all give the VIIA's range as 6200 nm at 10 knots. 6200 statute miles is exactly 10,000 km, so that many nautical miles should be not far off that mark.
I'm running a patrol in one right now, and I LOVE IT!