Depending on the size of your boat you may need more than one. Boats less than 26' have to have at least one B-1 fire extinguisher on board. Boats 26'-40' need to have at least two B-1 fire extinguishers on board.
Graphite is an electric conductor, consequently, useful in such applications as arc lamp electrodes. It can conduct electricity due to the vast electron delocalization within the carbon layers (a phenomenon called aromaticity).
Well-formed crystals of graphite are quite rare in nature, and most graphite occurs in its massive form. It is a metallic mineral, black to dark gray in color, with a distinctive greasy feeling. As with many mineral properties, this greasy nature is a reflection of its internal crystal structure.