Abstract: A procedure and apparatus for wireless measurement of the speed of a small craft, such as a surfboard or a boat, wherein the speed of the craft is measured with the aid of a speed pick-up by means of a separate measuring and transmitting device attached to the craft's bottom and in wireless fashion transmitted to a separate receiver device. In order to achieve efficient wireless measurement, the speed of the craft is detected from the voltage induced in the windings of an electric generator connected to a rotating speed measuring element and is telemetrically transmitted to the receiver device by using a magnetic field, and the electric energy required for the transmitter device is formed of the voltage induced by said electric generator.