In this paper the wake wash phenomenon produced by High Speed Craft (HSC) is analysed. Briefly the hydrodynamic phenomenon of wake wash is described indicating the parameters influencing the generation of wake wash from HSC at different speed and depth. The critical conditions for typical dimensions and speed of HSC are identified. In presented case study the wake wash generated by three catamarans actually operating in Croatian coastal waters is assessed. For each of them the actual route is analysed and flow regimes and critical points where wake wash could occur are identified. The wake wash values are assessed using the database of field measured wake wash for similar size catamarans published in literature. These values are propagated to shoreline and the obtained results are used to propose the maximum speed for which the generated wave height is still complying with the International Rules.
The introduction of high-speed ferries created enormous market opportunities for vessel operators, designers and shipbuilders. More and more ferry routes are served by High Speed Craft (HSC) and new, larger and faster HSC are expected to replace some of existing conventional ferries. Even though these new routes can offer transportation benefits, they may also generate conflicts between ferry operators and Environmental, Coastal and Maritime Authorities. If a ship operates at high speed in shallow water then the production of long-period waves in the leading part of the wake is unavoidable. The problems range from dangerous waves in bathing areas to erosion of coastlines, undesirable motions of moored ships, potential impacts on marine wildlife, emissions and noise. The conflicts have lead the Authorities in a number of countries to require HSC operators to include an assessment of wake wash effects. For example in Denmark, the operator of HSC has to document that the wash does not exceed along the entire route a prescribed wave height criteria defined as: