noon
Feeling thoroughly wretched , they were glad to accept Hans Koppe 's offer to lie down on a long locker . At noon , U75 came to the surface . The storm , being short forecasted , had quickly blown itself out , but the waves still ran high . It was a prearranged plan on the part of the three U-boats operating in the English and Bristol Channels to communicate with each other by wireless at noon and at midnight . U75 's wireless had a range of about 180 miles , and although it could be `` jammed '' , the call could not be tapped by vessels other than the one for which it was intended . To make doubly sure , the messages were sent in code . For nearly ten minutes U75 `` made her number '' without eliciting any reply .