Estimated towing tank power

Estimated towing-tank power is the effective power (EHP, also written P_E) derived by scaling a model resistance test to full scale through the ITTC procedure: P_E = R_T times V, where R_T is the extrapolated full-scale total resistance at ship speed V. The model total coefficient is split into frictional and residuary parts, the friction component is rescaled from model to ship Reynolds number using the ITTC-1957 line with form factor, the residuary part is held constant at equal Froude number, and a correlation allowance C_A is added. Delivered and shaft power then follow by dividing EHP by the quasi-propulsive coefficient and the shaft transmission efficiency. EHP is naked-hull tow power, not the power the engine must deliver.