A technique to optimise a shipping channel - design approach based on hindcast wave conditions and dynamic vessel response studied for two harbour cases

With vessel size increasing and the pressure on port Authorities to be operational at all times, many ports around the world need to redesign their entrance way. Channel deepening is a costly process and consequently it is critical to identify which dredging profile will allow the desired operability with minimal - dredging efforts, without compromising the safety of the transit. A method satisfying the 2014 PIANC channels design guidelines is presented, which combines a highresolution wave hindcast technique with dynamic ship motion modelling. It involves building a 10 year history of required depth profiles which are then combined in order to provide a tailored answer to the channel optimisation problem. The required depth profiles are established by combining numerical and semiempirical methods, considering various environmental factors such as tides, storm surge, infra-gravity waves, swell and wind waves as well as ship-related factors like squat and turning heel. A solution to the optimisation is expressed in terms of percentage of operability. The methods are illustrated in the context of two markedly different entrance channels. One is a roll affected transit and the other has strong tidal currents which interact with a wave field that is essentially co-linear with the leads. The results of both cases are examined in different ways with the former being optimised from a percentage of operability and the later using physical criteria, such as thresholds on the significant wave height.