Exam Question

Propulsive efficiency is a measure of how effectively the power delivered to the propeller is converted into useful thrust to propel the ship. It is primarily affected by hydrodynamic losses, such as rotational energy loss in the slipstream (swirl), tip vortex losses, and hub vortex losses. The devices listed are energy-saving devices (ESDs) designed to recover a portion of this lost energy, thereby improving the overall propulsive efficiency.
The overall propulsive efficiency ($$\eta_P$$) is given by:
$$ \eta_P = \frac{T_e \times V_s}{P_D} = \frac{\text{Effective Power (Thrust Power)}}{\text{Delivered Power}} $$
Where: