They run on the surface, as they always do when they are not making a positive effort to sink a convoy, so they can send and receive radio messages. Beck gives one to Oberfunkmaat Huffer, explaining what has just happened, and Huffer gives it to one of his Funkmaats, who sits down in front of U-691 ’s Enigma machine and encrypts it using the key for the day, then taps it out on the radio.