Keyless bore propellers are press fitted on the shaft cone. Oil is injected under pressure between the bore and the shaft by means of pumps feeding a system of grooves in the propeller bore. The grooves facilitate the spread of oil between the surface and the coefficient of friction is in this way temporarily reduced to less than 0.02. It is then quite easy, using a hydraulic device, to push the propeller against the taper into sufficient degree of interference. The propeller is pushed up a precalculated distance. The temperature is included as a variable due to the fact that the shaft and propeller are made of different materials.