For small boats which are normally used for recreational purposes, regulations do not require them to have an extinguisher on board. A boat with a length of below 26 feet needs one fire extinguisher. 26 – 40 feet require two extinguishers. Any boat with a length above 40 feet requires three fire extinguishers.
Which Fire Extinguisher is Right for Me? Our recommendation is to have a tri-class (1A:10BC) fire extinguisher on board your boat. We also suggest you have more than the Coast Guard requires. A tri-class dry chemical extinguisher will meet most boaters’ needs. As fire extinguishers are required on most boats, you most likely have one aboard.
Boat Fire Extinguisher Regulations, Classes & Maintenance
You are required by law to have a fire extinguisher on board if your boat has an engine and meets any of the following conditions: Your boat has closed compartments where portable fuel tanks may be stored. Your boat has a double bottom that is not sealed to the hull and that is not completely filled with flotation materials.
Notably, outboard-powered boats without any closed compartments that could hold explosive vapors or gasses (think: simple skiffs, garveys, etc.) are not required to carry fire extinguishing equipment by federal law. The first takeaway is that portable fire extinguishers aboard all recreational boats must not be older than 12 years.
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Buyer's Guide to Marine Fire Extinguishers Video Answer
Reference:
https://www.usfa.fema.gov/
https://en.wikipedia.org/wiki/Fire_extinguisher