How Many Fire Extinguishers Must Motorboats Between 26 And 40 Feet Have Aboard?

How Many Fire Extinguishers Must Motorboats Between 26 And 40 Feet Have Aboard? Boats 26′-40′ need to have at least two B-1 fire extinguishers on board. If the boat has a USCG approved fire extinguisher system installed for protection of the engine compartment, then the required number may be reduced. How do I calculate how