Since the English Channel was relatively shallow, and was partially blocked with minefields by mid-1940, U-boats were ordered not to negotiate it and instead travel around the British Isles to reach the most profitable hunting grounds.
Eftersom den Engelske Kanal har begrænset vanddybde og var spærret af minefelter fra midten af 1940, havde ubådene ordre til ikke at benytte den og i stedet sejle rundt om de britiske øer for at nå frem til de mest gunstige positioner.