When the need arose to go in the bilge or chech the batteries or go diving outside the boat to make repairs they alwats used the DRÄGER TAUCHRETTER . This acted as a life jacket or a breathing apperatus when underwater. Inside the rubber-canvas vest was a small air flask for breathing underwater or when the air in the boat was all used up.If the boat was under a prolonged attack and the air became foul the user of the vest could turn a small lever on the mouth piece to breath in air from the boat that has been purified from a small tin inside of the vest.