Nasa Electromagnetic Log And Data Box Speed through water with no moving parts. The new EML-2 electromagnetic speed log measures the boat speed through the water with no moving parts. Robust and accurate, the sensor generates an alternating magnetic field below the boat and measures the resulting electric field produced by the boat moving through the water. With exellent linearity and a resolution of 0.1 Knot, over the range 0.2 to 40 Knot, the control box converts the sensor signal to boat speed, trip and total distance and sends it to any compatible NMEA-0183 display.
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