Speed Effect

The speed of the ship in the actual sea area is calculated by solving the following equilibrium equation.

Coordinate system

Forces and moments consist of the following;

Resistance in still water;
Hydrodynamic forces in oblique motion;
Propeller thrust;
Force acting on rudder;
Added resistance due to winds;
Added resistance due to waves;

The following table shows the conditions of the waves and winds in the calculation.

Wave and wind conditions based on Beaufort wind class

　The following table shows the conditions of the waves and winds in the calculation.
　The relationship between ship speed and power is shown in the figure below. The ship speed under the same power is calculated by solving the equilibrium equation from the power curve in still water and the power curve in actual seas with waves and winds, and the amount of ship speed decrease is calculated as the difference.

Relationship between speed and power