“…Although inherent problems of the wave buoy analogy with regard to filtering have been reported (e.g. Simos et al, [49]; Nielsen, [37]; Pascoal and Guedes Soares, [44]), the wave buoy analogy is, in theory, capable of estimating exactly those waves which are of importance to the ship, in the operational and navigational sense. That is, the wave buoy analogy estimates the waves to which the ship responds (Nielsen,[39], [40]).…”