The paper describes two instruments made for use on naval craft during the 1939–45 War. The first was fitted to auxiliary aircraft carriers, and indicated the mean wind direction, so that the vessel might be steered correctly for the take-off and landing of aircraft. The second instrument was fitted on larger naval craft, for meteorological purposes. Its function was to indicate, in various positions in the ship, the direction and speed of both the mean true and the mean apparent winds.The components used in both instruments are magslip transmission elements and electrical computing devices, which were developed for fire-control purposes and subsequently adopted for the meteorological applications.