Gasoline fumes are heavier than air and will settle to the lowest part of the boat's interior hull, the bilge. All motorboats, except open boats (see fire extinguishers section on next page), must have at least two ventilator ducts with cowls (intake and exhaust). Exhaust blowers are part of most boat ventilation systems. Permanently installed fuel tanks must be vented.

Most boat explosions occur from improper fueling. Portable gas tanks should be filled on the dock or pier, not on board. The vent on the tank should be closed and the gas pumped carefully, maintaining contact with the nozzle and the tank’s rim. Any spills should be cleaned up, the tank secured, and the vent reopened.

When filling inboard tanks, everyone should be sent ashore and the boat closed up. All electrical systems should be shut off. After filling up and before starting the engine, the blower should be run for at least four minutes. Take appropriate precautions to prevent spills. Avoid discharging oil and gas from your boat’s bilge. Toxic substances must be disposed of properly. Noncompliance may result in fines.

Boaters should routinely check for leaks in fuel lines and fittings, frayed wiring, and improperly rigged electrical systems.

Carbon monoxide gas is a potentially deadly byproduct of your boat’s engine. Each year boaters are killed or injured by carbon monoxide. Stay away from exhaust areas and do not swim near exhaust vents. Never enter an enclosed area under a swim platform where exhaust is vented. Only one or two breaths of the air in this “death chamber” can be fatal. Keep air moving through the boat to avoid problems.

Gasoline engines, except outboards, must have an approved (USCG, SAE, or UL) backfire flame control on the carburetor to prevent ignition of gasoline vapors in case the engine backfires. It should be maintained regularly and can be cleaned with hot, soapy water or a commercial cleaner.