New Concepts for Shipboard Sea State Estimation

The wave buoy analogy is a tested means for shipboard sea state estimation. Basically, the estimation principle resembles that of a traditional wave rider buoy which relies, fundamentally, on transfer functions used to relate measured wave induced responses and the unknown wave excitation. This paper addresses however a newly developed concept of the wave buoy analogy but the approach presented herein is, on the contrary, not relying exclusively on transfer functions. Instead, the method combines a signal -based part, estimating wave frequency, and a model -based part, estimating wave amplitude and phase, where only the model -based part depends on transfer functions whereas the signal -based part relies on the measured vessel response alone. Case studies in terms of hypothetical examples show that the method is capable to reconstruct fully the wave elevation process of a sinusoidal regular wave; which include estimation of the wave's frequency, amplitude and phase. At this stage, the method is far from being a useful means in practical, real situation applications but the method provides, indeed, a valuable step towards developing new approaches for shipboard sea state estimation.