Even though the German Navy wasn't the strongest in the reagion, I believe a combination of the Luftwaffe, heavy guns, U-Boats and the Kriegsmarine surface fleet would have been sufficient to combat the Royal Navy.
Quote:From mid July the Luftwaffe stepped up the military pressure by attacking the channel ports and shipping to establish command of the Straits of Dover, while German heavy guns were installed around Calais to bombard the Dover area where the first shells started to fall during the second week of August.
By the end of July the Royal Navy had to pull all its larger warships out of the channel because of the threat from German aircraft.
