Abstract
Resistance tests, self-propulsion tests and wake measurements in the plane of propeller were carried out for a VLCC model which was roughened artificially. The tests were made varying the roughened part lengthwise. As a result it was found that wake fraction was affected significantly by the roughness of the last quarter length of a ship, while thrust deduction fraction and relative rotative efficiency were almost unchanged for any surface roughness conditions for the same surface roughness of each part. Such a change of wake fraction due to local surface roughness can be explained well by the turbulent boundary layer calculations for smooth and roughened surfaces.
