Estimation of wind sea and swell using shipboard measurements – A refined parametric modelling approach

• A method for estimation of wind sea and swell using ship responses is proposed.
• The estimation method is based on JONSWAP model for double-peaked spectra.
• The estimated main integral parameters of waves are fairly close to the true values.

Shipboard wave estimation has been of interest in recent years for the purpose of decision support. In this paper, estimation of sea state is studied using ship responses and a parametric description of directional wave spectra. A set of parameters, characterising a given wave spectrum is estimated through an optimisation problem using global search basin with proper constraints. The cost function is established based on the difference between the energies of a set of measured ship responses and the corresponding theoretical spectral moments. A partitioning procedure is applied, which is able to separate swell components from wind seas.