Wave energy’s field has been growing up in the last few years, with several power extraction devices. It represents an important part for future energy scenario. ?? ISWEC, among these devices, takes advantage of pitch motion caused by incident wave. This motion, together with flywheel motion, generates the rotation of a gyroscopic unit around the PTO (power generator) axis. It is thereby possible considering a whole set of reasons to explain the importance of a correct design of a mooring system, especially talking about ISWEC. Above all, a mooring system has to ensure the station-keeping of device according to rules. For this reason, it is important to know the regulations.