**5. Ship Mission Profile**

The sea condition in which the ship sails will be first defined. The added ship resistance in service due to sea condition, which is relative to that in sea trial condition (calm sea condition), is quantified by the sea margin (SM), which is defined by Equation (7).

$$SM = \frac{P\_{E, \text{service}} - P\_{E, \text{trial}}}{P\_{E, \text{trial}}} \tag{7}$$

where *PE*,*service* is the ship e ffective power in service conditions and *PE*,*trial* is the ship e ffective power in sea trial condition.

The sea margin is modelled as the function of the fouling of hull and propeller, displacement, sea state and water depth. It is assumed that the ship displacement is the design displacement and does not change during the whole voyage including both transit in open sea and manoeuvre in close-to-port areas. In normal sea condition, when sailing in open sea, the ship sails in deep water and the ship resistance addition (10%) is mainly due to the sea state; while, when sailing in coastal and port areas, the ship resistance addition (10%) is mainly due to the shallow water and the e ffect of sea state is neglected. According to the above assumptions, in normal sea condition, the sea margins when sailing in both open sea and close-to-port area are 15% due to the combined e ffects of the ship fouling, displacement, sea state and water depth.
