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).
Graphite is a mineral composed exclusively of the element carbon. Graphite has the same chemical composition as Diamond, which is also pure carbon, but the molecular structure of Graphite and Diamond is entirely different. This causes almost opposite characteristics in their physical properties. Graphite is rather common mineral, but fine crystals are rare. Most Graphite mining areas produce enormous quantities from a single or several large Graphite vein s, but collector specimens in good crystals are not commonly encountered.