All watercraft using gasoline as fuel, except outboard motors, shall attach to the carburetor or carburetors a backfire flame arrestor that is approved for marine use and suitably secured to the air intake with flame tight connections, or any attachment to the carburetor or the engine air induction system by means of which flames caused by engine backfire will be dispersed to the atmosphere outside the watercraft in such a manner that the flames will not endanger the watercraft, persons on board or nearby watercraft and structures. All attachments shall be of a metallic construction with flame tight connections and firmly secured to withstand vibration, shock and engine backfire.