Abstract: The invention relates essentially to an apparatus for clearing the line of a marine speedometer with pressurized gas, wherein the invention connects a source of pressurized gas through a three-way valve to a diverter valve between the boat's speedometer readout and the pitot tube to allow a source of gas to pass through the three-way valve, and the diverter valve, out the pitot tube in the reverse direction, and thus clear particles therefrom. When the source of pressurized gas is turned off, the pitot tube will operate in the usual manner and the pressure of the moving boat will force air up to the diverter valve, thus closing the diaphragm of the valve and activating the speedometer to read accurately.