The backplate, a plate, ordinarily made from chrome steel, at times aluminium or carbon fibre composite, which is held towards the diver's back from the harness, also to which the diver's Most important cylinder or cylinders are attached. An underwater scooter will work the same way as being a motorboat. https://blogfreely.net/fowldamage5/en-kurallari-of-underwater-sea-scooter