Sons of the Sea Dad's Army : Season 3 Episode 14

Capt Mainwaring comes up with the idea of small armed patrols to wreak havoc with the enemy using a small reprocessed boat the bank has acquired After a practice on the river they get lost in the fog and they think they have drifted across the channel and are about to be captured by the German's but they are in for a shock when they find out where they really are.