Abstract QCM has been applied to open-water thrust and torque predictions of the ducted propellers with different positions of the propeller and duct. The QCM results are in good agreement with the experimental data of the propellers positioned inside a duct. The results of propellers in the downstream of the duct show no significant dependence on the length of the straight trailing vortex of the duct. Comparison with the results calculated without any duct has indicated no improvement of the calculated open-water characteristics by positioning the present duct in front of the present propeller.