This paper presents the results of analysis on the loss due to propulsion shaft friction in the oil lubricated stern tube, applied to ships. 1) The loss due to the oil lubricated stern tube bearing friction was estimated on the heat analysis of temperature measurement data under the maximum continuous output steady condition at the official sea trial. The loss of horse power was found to be 0.6∼0.2% in proportion to SHP or BHP at M.C.R.. 2) The loss due to the intermediate shaft block friction was estimated on the heat analysis of the temperature measurement data under the maximum continuous output steady condition at the official sea trial. The loss of horse power was found to be 0.01∼0.05% in proportion to SHP or BHP at M.C.R.. 3) The loss due to the thrust block friction was estimated by Eq. (1) in the paper. ΔH(PS)=μ×υ×P/75, Where, P=11×SHP or BHP (kg) υ=7m/s μ=0.005 The loss of horse power was found to be O.5% in proportion to SHP or BHP. Thus, the delivered horse power (DHP) on the oil lubricated stern tube applied to ships was estimated as follows. Aft engine ship DHP=1/(1.01) SHP or BHP Midship engine ship DHP=1/(1.015) SHP or BHP
