A number of final points to note with regard to the RAO data are as follows. Firstly, Flexcom uses linear interpolation to calculate RAOs and phase angles at wave headings and frequencies intermediate to those in the RAO file. Outside of the range of user-specified headings and frequencies, RAOs and phase angles are assumed to be zero, so it is important to ensure you cover the full range of conditions likely to be encountered in an analysis when inputting the RAO data. Secondly, specified phase angles represent a phase lag or lead relative to the wave at the vessel reference point. Thirdly, a positive phase angle denotes a phase lag relative to the incident wave harmonic. Finally, Flexcom requires that you use the same frequencies in specifying RAOs and phase angles at each vessel wave heading value. You do not however have to use the same frequencies (or indeed headings) if you are specifying RAOs for two vessels in an analysis – the RAOs can be at very different heading and frequency values, and in general would almost certainly be the case.
