It would seem from what Roskill is saying, as quoted below, that there was an encounter at sea that night, but that the Admiralty regarded the skirmish as inconclusive, so it is not clear what ships or boats the Germans thought had exploded or sunk. It may be that some things are getting lost in translation here, but the German reports of these incidents never seem that reliable.
Early next morning light forces (six M.T.Bs and three M.G.Bs) sent out from Dover were in touch with the convoy; but our wireless traffic had given the enemy warning of their approach. The coastal craft located their quarry close to the French coast, but the enemy had been thoroughly alerted. His shore batteries fired starshell to illuminate the scene, and the attackers were met by such concentrated gunfire that they could not penetrate the screen. Soon after this skirmish five destroyers, which had been on patrol off Beachy Head, arrived and engaged the German escort; the Windsor and Walpole fired torpedoes, but none of them hit. Little damage was in fact done to either side, and the raider safely reached Havre on the afternoon of the 14th.