A modified admiralty coefficient for estimating power curves in EEDI calculations

In the calculation of the EEDI for ships, the accurate estimation of the ship speed/power curves is of great significance. The objective of this paper is to give a more accurate estimation method of speed/power curves for container ships. First, the influence of three important factors on the EEDI value is studied, including the main engine power, the deadweight and the reference speed. And the calculation methods of the reference velocity are summarized. Next, based on the speed/power data from series of container ships, the estimation accuracy of the original admiralty coefficient formula is evaluated. Then, the constant power exponent in the admiralty coefficient formula is replaced by the hull form coefficients, and a modified admiralty coefficient formula is proposed. The modified formula proves to be more accurate than the original formula for the estimation of the power curve. Finally, the application results of the two estimation formulas are compared in the calculation of the EEDI for the container ship, and the modified formula is recommended.