Going up the Channel, while submerged , just isn’t going to work—they’ll run into one of the block ships that the Brits sank there to prevent U-boats from doing just that. The surface is the only way, and it’s a hell of a lot faster too. This raises the airplane issue. Airplanes search not for the boat itself, which is tiny and dark, but for its wake, which is white and spreads for miles on calm water. There will be no wake behind U-691 tonight—or rather, there will be, but it will be lost in random noise of much higher amplitude. Bischoff decides that covering distance is more important than being subtle at the moment, and so he brings her up to the surface and then pins the throttle. This will burn fuel insanely, but U-691 has a range of eleven thousand miles.