Processable rubber compositions contain a vulcanized fluorocarbon elastomer and wear reducing additives dispersed in a matrix of a thermoplastic polymeric material. This increased resistance exerts a braking thrust on the marine vessel. A microcomputer functions as a concentration sensing section and senses a concentration of ethanol contained in fuel based on the capacitance sensed by the capacitance sensing section and the temperature sensed by the temperature sensing section. The circuit board transfers alternative current into direct current that is provided to the light source.