An outboard motor includes an internal combustion engine provided with a pair of intake valves. The sensor is designed to generate a sensing signal corresponding to a rotary moment of the tube head or tube body and the control unit correlates the sensing signal with a reference signal and for generating a control signal from a characteristic value corresponding to a degree of correlation, in particular a maximum correlation or minimum correlation, for the positioning device. The low-temperature fluid flowing through the superconducting device is heated. The first spectral sensitizing dye is an anionic benzimidazole-benzoxazole carbocyanine, the second spectral sensitizing dye is an anionic oxycarbocyanine. The reflection band and the thermal emission band are detectable within the desired range of wavelengths.