Chapter 4: The Legal Requirements of Boating
Fire Extinguishers

Extinguishers are classified by a letter and number symbol. The number indicates the relative size of the extinguisher. For example, a B-II extinguisher has twice as much extinguishing agent as a B-I extinguisher. The letter indicates the type of fire it will extinguish.

Type A fires are of combustible solids like wood.
Type B fires are of flammable liquids like gasoline or oil.
Type C fires are electrical fires.

All vessels with a motor of any type are required to have a Type B fire extinguisher(s) on board. The only exception is if a vessel is of open construction, is less than 26 feet in length, has an outboard engine, and is not carrying passengers for hire.

Use this chart to determine the type and quantity of fire extinguishers required for your motorized vessel.

Length of Vessel	Without Fixed System	With Fixed System *
Less than 16 feet	one B-I is required if boating on federally-controlled waters	None
16 feet to less than 26 feet	one B-I * *	None
26 feet to less than 40 feet	two B-I or one B-II	one B-I
40 feet to less than 65 feet	three B-I or one B-II and one B-I	two B-I or one B-II
* Refers to a permanently installed fire extinguisher system * * Not required if a vessel is of open construction, is less than 26 feet in length, has an outboard engine, is not carrying passengers for hire, and is not on federally-controlled waters. One B-I extinguisher is required if on federally-controlled waters.

Extinguishers should be placed in an accessible area—not near the engine or in a compartment, but where they can be reached immediately. Be sure you know how to operate them.

Fire extinguishers must be maintained in usable condition. Inspect extinguishers regularly to ensure the following.

Seals and tamper indicators are not broken or missing.
Pressure gauges or indicators read in the operable range.
There is no physical damage, corrosion, leakage, or clogged nozzles.

Fire Extinguisher Charge Indicators

Check the charge level of your fire extinguishers regularly. Replace them immediately if they are not fully charged.

To check this style of extinguisher, depress the green button. If it is fully charged, the green button should pop back out immediately.
On this style of fire extinguisher, the needle indicator should be in the "full" range.

Backfire Flame Arrestors

Because boat engines may backfire, all powerboats (except outboards) that are fueled with gasoline must have an approved backfire flame arrestor on each carburetor. Backfire flame arrestors are designed to prevent the ignition of gasoline vapors in case the engine backfires.

Backfire flame arrestors must be:

In good and serviceable condition
U.S. Coast Guard–approved (must comply with SAE J-1928 or UL 1111 standards)

Periodically clean the flame arrestor(s) and check for any damage.

Ventilation Systems

The importance of ventilation is crucial. The purpose of ventilation systems is to avoid explosions by removing flammable gases. Properly installed ventilation systems greatly reduce the chance of a life-threatening explosion.

All gasoline-powered vessels, constructed in a way that would entrap fumes, must have at least two ventilation ducts fitted with cowls to remove the fumes. At least one exhaust duct must extend from the open atmosphere to the lower bilge. At least one intake duct must extend from a point at least midway to the bilge or below the level of the carburetor air intake.
If your vessel is equipped with a power ventilation system, turn it on for at least four minutes after fueling and before starting your engine.
If your vessel is not equipped with a power ventilation system (for example, a personal watercraft), open the engine compartment and sniff for gasoline fumes before starting the engine.

Vessels built after July 31, 1980, which contain power exhaust blowers in gasoline engine compartments, must have the above warning sticker placed near the instrument panel.

Powerboats are built to ventilate the engine when underway. As the boat moves along, an air intake scoops up fresh air and forces it down the air duct into the engine compartment. The exhaust sucks out the explosive fumes from the lowest part of the engine and fuel compartments.

Mufflers and Noise Level Limits

Vessel operators may not hear sound signals or voices if the engine is not adequately muffled.

The exhaust of every internal combustion engine on any vessel must be effectively muffled by a muffler or underwater exhaust. That is, the engine’s exhaust must be muffled or suppressed at all times so as not to create excessive noise.
The use of cutouts is prohibited.
It is illegal to remove or modify the exhaust or muffler system of a vessel.
Vessels involved in a marine event authorized by the Massachusetts Environmental Police are exempt from the requirements above.

Vessel Safety Checks

The U.S. Coast Guard Auxiliary and U.S. Power Squadrons will perform a Vessel Safety Check (VSC) of your vessel and equipment free of charge. This inspection covers federal and state requirements. If your vessel meets all VSC requirements, you will receive a VSC decal. If your vessel fails to meet all requirements, no report is made to any law enforcement agency.