Which of the following is required to have a backfire flame arrestor?

A backfire flame arrestor is a safety device designed to prevent flames that may occur during backfire situations in internal combustion engines from escaping into the engine compartment, where they could ignite flammable vapors.

For boats with gasoline inboard engines, having a backfire flame arrestor is a critical safety requirement. It helps reduce the risk of fire, making it essential for compliance with safety regulations. This is especially important because gasoline vapors can accumulate in the engine compartment, posing a significant fire hazard. Therefore, boats equipped with such engines are mandated to have this safety feature installed to minimize the danger to passengers and crew.

Other types of watercraft, such as kayaks, canoes, and boats that rely on electric motors, do not require backfire flame arrestors because they either do not use gasoline engines or do not have the potential for backfire incidents associated with internal combustion engines. Sailboats under 14 feet typically fall into the same category, as their size and often simple engine configurations do not necessitate this safety equipment.