Green Cruising of High-Speed Small Craft in the Baltic Sea Region

Abstract

The Baltic Sea is a highly sensitive marine environment, where pollution and emissions from human activity may have long-lasting ecological and socio-economic consequences. While international regulations have increasingly addressed emissions, fuel consumption, and pollution from large commercial vessels, small high-speed craft, especially leisure and recreational boats, remain less regulated despite their large numbers and intensive use in coastal areas. In the Baltic Sea Region, where boat ownership is among the highest in the world, the cumulative environmental impact of small craft is therefore increasingly relevant. Reducing fuel consumption, emissions, and coastal disturbance from these vessels requires not only cleaner propulsion systems, but also improved hydrodynamic design and more efficient operation. This docent presentation addresses the challenge of green cruising for high-speed small craft, with particular focus on hydrodynamic performance, and energy efficiency. The presentation first discusses the environmental and regulatory background of small-craft operation in the Baltic Sea Region. It then presents a sequence of research activities aimed at improving the design and performance prediction of high-speed small craft, with emphasis on stepped hulls. Stepped hulls can reduce wetted area and resistance by introducing transverse discontinuities on the hull bottom, but their design is challenging because of strongly nonlinear flow phenomena, including flow separation, ventilation, cavity development, reattachment, and three-dimensional vortical structures.

The presentation will review a coherent sequence of studies led by me and conducted within my research group in collaboration with national and international partners. These studies include reduced-order modelling, CFD simulations, towing-tank experiments, systematic hull-form investigations, and recent analyses of the hydrodynamic response of stepped planning hulls in regular and irregular waves. Together, this body of work demonstrates how deeper physical understanding of underbody flow processes can support the development of cleaner, safer, and more energy-efficient high-speed craft for the Baltic Sea Region.