For the design of sailing vessels, the use of Dynamic Velocity Prediction Programs is expanding, as naval architects start to consider the effects of waves and varying wind conditions in order to design faster, safer and more efficient vessels. Many models that predict the unsteady hydrodynamic response are available, but for sail aerodynamics, few models have been presented, and the quasi-steady assumption is instead commonly used. The aim of this paper is to develop a time-domain model for unsteady sail aerodynamics that can handle arbitrary motions and requires only limited input. The proposed model is based on the Indicial Response Method, with specific adaptations to handle the additional complexity of sail aerodynamics. The model’s predictive performance is evaluated against URANS CFD results for several cases of increasing complexity. This includes a 3D upwind sail plan subjected to pitching motion, where comparisons are also made with the common quasi-steady (Q-S) assumption. Compared to this, the proposed model delivers significantly better predictions for the amplitude of lift, thrust and sideforce. However, the drag amplitude is over-predicted by the model, and as a result, there is a significant misprediction of thrust phase. While there is a need to improve the prediction of unsteady drag, this paper shows that the model represents a significant improvement over the Q-S assumption, for unsteady performance prediction on timescales shorter than the wave period.

Rapid performance prediction tools are required for the evaluation, optimization, and comparison of different wind propulsion systems (WPSs). These tools should capture viscous aerodynamic flow effects in 3D, particularly the maximum propulsion force, stall angles, and interaction effects between the lift-generating units. This paper presents a rapid aerodynamic calculation method for wing sails that combines a semi-empirical lifting line model with a potential flow-based interaction model to account for 3D interaction effects. The method was applied to a WPS that consisted of several wing sails with considerable interaction effects. The results were compared to CFD RANS simulations in 2D and in 3D. For the evaluated validation cases, the interaction model improved the prediction considerably compared to when the interaction was not accounted for. The method provided acceptable driving force, moments, and stall predictions, with negligible computational cost compared to 3D CFD simulations. 

This report demonstrates the qualifications of RISE to carry out CFD for ship self-propulsion, thus predicting the delivered power. The procedures were fully developed at SSPA which became fully integrated into the Maritime Department of RISE by 2023-01-01. An outline is given of the best-practice guidelines used at SSPA/RISE and how they comply with the relevant ITTC recommendations for verification and analysis. In addition, an overview is given of previous validation studies performed for a wide range of ships, including comparison with both model-scale and full-scale data. Complete references are provided to reports and publications in which these SSPA studies and methods are described in detail.

Because of the long history of the Finn Dinghy sailing class, the difference between a gold medal and a mediocre result often comes down to personal mistakes of the sailor, or to who has the most optimised equipment. Regarding the latter, the Finn class rules permit certain design variations of the hull, mast, sail and rudder. In the current contribution, we describe a method for developing a customised rudder system aimed at optimal performance during the Tokyo 2020 Olympics. Based on hydrodynamic analysis of existing rudder designs, an improved rudder geometry was developed. Based on the concept geometry, the rudder and tiller were structurally designed and manufactured to achieve high stiffness and sufficient strength, while respecting the minimum mass requirements as specified by the rules.

Road haulage causes undisputed negative environmental impact in terms of CO2-emissions, noise, infrastructure damage, congestion, road accidents and is energy intensive. At longer transport distance (e.g. trans-ocean) maritime transport is preferable as it is more cost efficient. At shorter distances, there are financial, operational, market-related and regulatory issues that make waterway transport less attractive. Meanwhile, as waterway transport is favorable from an environmental perspective, the support for modal shift from road to sea has become an integral part of transport policy both at EU-level and in several countries across Europe. Among the different types of shipping (trans-ocean, short-sea, coastal), inland shipping is of particular importance when it comes to reduce congestion on roads. Ports are most often located in or near large cities, which in particular causes congestion on access roads to ports and the cities, and also in the countries in general. Hence, whereas cost is a barrier that must be overcome, using inland waterway transportation (IWT) is preferable from an environmental perspective, and a modal shift is a highly prioritized issue by governments. In some central European countries, IWT is well developed, while in countries such as Sweden, the share of inland shipping is very low, < 1%, and with no or little container traffic. With well-functioning fairways in inland waterways in Sweden, there is a large potential for increasing its utilization.

For a sailing yacht, depowering is a set of strategies used to limit the sail force magnitude by intentionally moving away from the point of maximum forward driving force, potentially reducing the ship speed. The reasons for doing this includes among others; reduction of quasi-static heeling angle, structural integrity of masts and sails and crew comfort. For a wind powered cargo ship, time spent on a route is of utmost importance. This leads to the question whether there is a performance difference between different depowering strategies and if so, how large. In this research, a wind-powered cargo vessel with rigid wings is described in a Velocity Prediction Program (VPP) with four-degrees of freedom, namely surge, sway, roll and yaw, with a maximum heel angle constraint. The resulting ship speed performance for different depowering strategies are investigated and the implications in roll and pitch-moments are discussed. The wind conditions when depowering is needed are identified. A statistical analysis on the probability of occurrence of these conditions and the impact of the different depowering strategies on the required number of days for a round-trip on a Transatlantic route is performed.

In this paper, an improved procedure for strongly coupled prediction of sailing yacht performance is developed. The procedure uses 3D RANS CFD to compute the hydrodynamic forces. When coupled to a rigid body motion solver and a sail force model, along with a rudder control algorithm, this allows sailing yacht performance to be predicted within CFD software. The procedure provides faster convergence when compared to previously published methods. The grid motion scheme, partially using overset grid techniques, means that correct alignment between the free surface and the background grid is ensured even at large heel angles. The capabilities are demonstrated with performance predictions for the SYRF 14 m yacht, at one true wind speed, over a range of true wind angles, with one up- and one downwind sailset. The results are compared to predictions from the ORC-VPP for a yacht with similar main particulars.

The purpose of this study is to compare the accuracy of two cost-effective aerodynamic methods used to predict the performance of a large scale wind propulsion system. The methods are evaluated regarding their ability to predict the performance of a configuration consisting of four rigid wing sails of an approximate height of 80 m and average chord length of 23 m. The distance between the wing sails, from trailing to leading edge, is about one chord length. For a limited number of test cases, it is evaluated how well the methods balance computational cost and accuracy and their potential to predict the performance of multiple rigid wing configurations. Two different types of aerodynamic methods are compared; one method under development based on potential flow/lifting line theory in combination with pre-calculated 2D CFD RANS data (CORR-SILL), and a vortex lattice method (VLM). The results from the two different methods are compared with 3D CFD RANS simulations. The parameters compared are the induced velocities around the sails, system forces and longitudinal center of effort. This paper indicates that both evaluated methods show potential to predict the magnitude and distribution of the forces on multiple wing sail, with a large reduction of computational effort compared to CFD.

Trans-ocean liner shipping companies adopt slow steaming during periods when the market is characterised by low demand, high fuel prices, low freight rates and overcapacity. The most recent instance in which this occurred was the period following the 2008/2009 global financial crises, and the speeds have not yet rebounded to the pre-crisis levels. Most of the existing research regarding slow steaming takes environmental, economic and maritime engineering perspectives, meaning that the phenomenon is studied from the viewpoint of ship owners. The purpose of this paper is to explore the effects of slow steaming from the shipper’s perspective. 

Although not originally developed for research use, the Automatic Identification System (AIS) enables its data to be used in research. The present paper provides a structured overview of how AIS data is used for various research applications. Ten areas have been identified, spread across maritime, marine and other journals. Many stakeholders beyond the most frequently mentioned – authorities and maritime administrations – can benefit from the research in which AIS data is used. AIS data can be incorporated in various types of modelling approaches and play a small or large role as a source of data. AIS data can also be validated or used to validate research from other data sources. Although a large amount of AIS-based research adds to the literature, there is still a large potential for using AIS data for research by making greater use of the variety in AIS messages, combining AIS with other sources of data, and extending both spatial and temporal perspectives.