Admiralty Coefficient

The Admiralty Coefficient is developed to allow comparison between different ships. It can also be used to give a first estimate on the power requirement or speed obtainable by using data from existing ships. This requires that the new ship hull if fairly similar to the existing one but it might have different displacement, shaft power and/or speed requirement. The normal procedure is to calculate the Admiralty Coefficient C for the known ship and then use this value for the new design.

It is important to note that the Admiralty Coefficient only depends upon the displacement, the speed and the power. This is of course not enough to account for all of the hydrodynamic effects affecting the resistance of the hull, flow to the propeller and the propeller efficiency. It can because of this only be used for rough early estimates.

Typical range of the Admiralty Coefficient C is between 400 and 600 with higher numbers for efficient designs.

\begin{align} C= \frac{D^{2/3}V^3}{P} \end{align}

where:

  • D - Displacement in ton
  • V - Speed in knots
  • P - Shaft power in kW

Calculators

Calculate Admiralty Coefficient

Calculate Speed

Calculate Power