In the most general case vessel RAOs and phase angles vary with i) incident wave heading and ii) frequency. The definition of wave heading is described in detail shortly. The variation of RAOs and phase angles with frequency is well understood. This general variation of RAOs with wave heading and frequency is reflected in the format of the RAO file, where RAOs are defined first in terms of wave heading, and then at each heading value in terms of wave frequency. Of course, in very many analyses, namely those with one or more collinear regular waves or a uni-directional random sea, the question of wave heading does not arise, and this is reflected in Flexcom RAO file format.
