Blimp maintenance crews need a lot of the same agility aloft required of sailing men in the days of the windjammers. To scan the outer surface of a blimp envelope for rents or rips is a high job on lines or portable extension ladders. Navy crews periodically go over the big airships from engine to gas cells in a hunt for signs of stress or wear. Note the size of fins and rudder at the trail of the blimp.