Case Study based Investigation on Impact of Added Wave Resistance Models on Vessel Power Consumption and Routing

Kurzfassung

Shipping is an important factor for the climate crisis, since its exhaust gases account for over three percent of global greenhouse gas (GHG) emissions. This is reflected in the GHG Strategy of the International Maritime Organization (IMO), which requires the maritime industry to adopt measures to ensure an uptake of near-zero GHG solutions by 2030 and reach net zero GHG emissions by 2050. To achieve this goal, all available energy saving means, such as alternative fuels, novel propulsion systems, hull modifications, as well as operational measures, e.g. slow steaming, fleet management, just-in-time port calls and voyage optimization, need to be considered. With regard to the quantification of power demand and emissions, as well as utilization in voyage optimization tools, prediction models that can accurately quantify ship resistance and power consumption with minimal computational effort are essential. While robust, semi-empirical models for vessel calm water resistance are firmly established, added resistance in waves is often addressed via models of very low fidelity. Thus, this paper explores the impact of different added wave resistance models on the power consumption prediction and moreover their effect on the weather routing. For this purpose, multiple approaches for the calculation of added wave resistance and in turn power demand, such as simple one-equation models and semi-empirical models, which account for irregular 2D directional wave spectra, are compared. Utilizing a set of voyage calculations, the influence of the respective models on overall power consumption prediction and routing details is discussed. The results suggest that even simple models, as long as they ac- count for the directionality of the waves, can yield satisfactory results.