Because of the successful application of hydrofoils on the America's Cup catamarans in the past two campaigns the interest in foiling sailing craft has boosted. Foils have been fitted to a large number of yachts with great success, ranging from dinghies to ocean racers. An interesting question is whether one of the slowest racing boats in the world, the Optimist dinghy, can foil, and if so, at what minimum wind speed. The present paper presents a comprehensive design campaign to answer the two questions. The campaign includes a newly developed Velocity Prediction Program (VPP) for foiling/non-foiling conditions, a wind tunnel test of sail aerodynamics, a towing tank test of hull hydrodynamics and a large number of numerical predictions of foil characteristics. An optimum foil configuration is developed and towing tank tested with satisfactory results. The final proof of the concept is a successful on the water test with stable foiling at a speed of 12 knots.

Lean production has over the last decades emerged as the most important paradigm for production, with the assembly processes in focus, including the objective to minimize non-value-adding work. Thus, much attention has been on the work of the assembly operator. However, little focus has been devoted to how the new requirements from lean production have been transformed into materials supply systems supporting the assembly processes. Hence, the purpose of this thesis is to contribute to increased knowledge about the relation between assembly processes and materials supply systems design.A framework is introduced in this thesis, describing how requirements from the assembly processes are transformed by the materials supply system into the actual materials flow. In the results of this thesis, a model structuring requirements in materials supply and assembly processes is proposed, tested, and subsequently different requirements were identified. Materials exposure is introduced as the transition from the materials supply system to the assembly system. Results show that that the materials exposure has a large impact on assembly workstations performance in terms of space needed, non-value-adding work and ergonomics. Further, an experiment showed that the materials exposure factors with the largest impact on picking time were packaging, angle of packaging and height above floor.Major contributions in this thesis are the identification and structuring of requirements in assembly processes and materials supply systems, and explaining how the materials exposure affects the assembly processes. How this knowledge can be applied in the design of new, or redesign of existing, production systems and materials supply processes in particular, is a managerial contribution.

The purpose of this paper is to describe how a technical university have endeavoured into sports. This short paper will provide examples of a different approach to research in sports combined with technology. Chalmers University of Technology in Gothenburg, Sweden has for the last few years become engaged into research using sports as an application area for applied research. The research efforts has utilised the way that sports are organised in Sweden, with the sports confederations and clubs providing the problem areas to base the research around. For the university several aspects have been key in the research efforts. Chalmers will not do research in sport science, but all researchers will stay in their respective area of expertise. This short paper will focus on how this approach strengthens our research in diverse areas such as the automotive industry (with examples from production logistics and crash safety) for the forest industry (composites and cellulose research) and astronomy. But they have now all been further developed by sports.

This thesis concerns the supply of components to assembly in production sys- tems, and introduces materials exposure as the interface between materials sup- ply systems and assembly systems. The purpose of the thesis is to explain how materials exposure influences the performance of materials supply systems and assembly systems. The supply of components is crucial for assembly, for in serving the requirements from assembly. Still, the materials supply system has to remain efficient. In this way, materials exposure impacts the performance of a production system as a whole.The thesis is a based on five studies, all of which depart from theoretical frame- works developed from literature and empirically applied within the Swedish automotive industry. Four case studies and one experiment were conducted to answer three research questions, and the results are published in five papers.The results of the thesis provide several theoretical and practical contributions. Both the position of the exposure and the size of the packaging for a component impact the performance of the assembly workstation performance in terms of space required, non-value-adding work, and ergonomics. Materials exposure impacts manual picking time at assembly lines, for which packaging is the most influential factor, followed by angle of exposure and height of the exposed com- ponent. Materials exposure further impacts the configuration of the in-plant ma- terials supply system by requiring additional activities in the in-plant materials supply system, which impacts its performance. Concerning the impact of choice of packaging used in materials exposure, a model to evaluate the impact a pack- aging has on the performance of the materials supply system was developed. The Materials Flow Mapping methodology is another contribution that describes the activities in materials supply systems, as well as categorises the activities in material flows into materials handling, transportation, storage, and administra- tive activities.This thesis explains how the materials exposure influences the performance of materials supply systems and assembly systems. It shows how materials expo- sure impacts the assembly system performance and the in-plant materials supply system performance, and finally, how the packaging for materials exposure im- pacts the performance of the materials supply systems and assembly systems. The thesis can further be used as a guide for how materials should be exposed and in the selection of packaging for materials exposure. The most beneficial managerial use would be in the design and operation of assembly systems, mate- rials supply systems, and in particular, materials exposure.

The issue of speed is more complex for RoRo/RoPax vessels than other segments. A Swedish research team has addressed the preconditions for introducing slow steaming in Northern Europe and asked operators in Scandinavian waters how they prepared and have acted under SECA

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. 

Delrapporter inom HA1 i NÖKS projektet som inkluderas i denna rapport:NÖKS transportteori, godsflöden och rambetingelser för trafiksslagsskifte från land till sjöNÖKS fartygstyper resp ny teknologiInvesteringsplaner och utvecklingsbehov för Containershipping inom NÖKS området

When container shipping lines experience over-capacity and high fuel costs, they typically respond by decreasing sailing speeds and, consequently, increasing transport time. Most of the literature on this phenomenon, often referred to as slowsteaming, takes the perspective of the shipping lines addressing technical, operational and financial effects, or a society perspective focusing on lower emissions and energy use. Few studies investigate the effects on the demand side of the market for container liner shipping. Hence, the aim of this study is to elaborate on the logistics consequences of slow-steaming, particularly the strategies that Swedish shippers purchasing deep sea container transport services employ to mitigate the effects of slow-steaming. Workshops and semi-structured interviews revealed that shippers felt they had little or no impact on sailing schedules and were more or less subject to container shipping lines’ decisions. The effects of slowsteaming were obviously most severe for firms with complex supply chains, where intermediate products are sent back and forth between production stages on different continents. The shippers developed a set of strategies to cope with the low punctuality of containerised shipping, and these were categorised in the domains of transfer-the-problem, transport, sourcing and distribution, logistics and manufacturing, and product design. All firms applied changes in the transport domain, although the lack of service segmentation limited the effects of the strategy. Most measures were applied by two firms, whereas only one firm changed the product design.

Trans-ocean liner shipping companies adopt slow steaming during periods when the market is characterized by low demand, high fuel prices, low freight rates and over capacity. The latest instance this has occurred is in the period following the 2008/2009 global financial crises and the speeds have not yet rebound to the pre-crisis levels. Most of the existing research regarding slow steaming is from environmental, economical and maritime engineering perspective, meaning that the phenomenon is studied from the ship owners’ perspective. The purpose of this paper is to explore the effects of slow steaming from the shippers’ perspective. A structural literature review on the main subject has been performed and the same resulted in a matrix of different effects of slow steaming on the shippers already identified and studied in the existing literature. Furthermore, six global companies positioned in Sweden have been studied and the data from the case companies has been collected through face-to-face interviews. The findings of the interviews have been summarized, presented and discussed at a workshop with all case companies’ representatives. The results of the study show that the shippers were firstly affected by slow steaming in 2008 and 2009 simply through increased sailing times that affected their supply chains. Reliability has been regarded as more important than the sailing time itself but the improvement on the same has not been observed so far. Furthermore, the interviewees believe that if the sea transport option is unreliable, air and rail are considered as substitute supply chains and the same also affects the last mile mode choice. Remarkably only one shipper acknowledged the importance and existence of environmental benefits; however increased reliability or cost reduction, as the benefits, have not been recognized by the interviewees.

About 90 per cent of the total volumes of goods that are imported to, or exported from, Sweden have been carried using maritime transport at some part of the transport chain. Swedish industry and commerce are hence heavily dependent on access to effective and efficient maritime transport services. At the same time the IMO estimates that roughly 3 per cent of the global CO2 emissions stem from maritime transport. In addition, the shipping industry is the source of about 15% of the global SOX and NOX emissions. The challenge at hand is hence, to reduce the negative external effects of shipping while at the same time accommodating an increasing demand, without adversely affecting the shippers’ ability to fulfill their needs for maritime transport. One of the most potent measures for reducing fuel consumption and consequently, emission, is reduction of sailing speed; so called slow steaming. Due to the non-linear correlation between speed and fuel consumption (e.g. the admiralty formula which estimates a cube function; meaning a 10% speed reduction yields 27% fuel consumption reduction), even marginal speed reduction will result in substantial reduction in fuel consumption. Historically, any time slow steaming has been broadly employed in the shipping industry; it has been so unilaterally by the ship owners. The rise in the application of slow steaming by linear shipping companies, is attributed to the flaccid demand, abundance of capacity, high fuel prices and low freight rates. Based on the existing knowledge, it is reasonable to anticipate that, despite the negative abatement costs and potency of slow steaming as a measure for reduction of emissions, its use will likely decline as soon as the market conditions rebound. The purpose of this study is to explore and explain the shippers’ ability to demand, and manage the consequences of, slow steaming maritime transport services in their supply chains. The Slow Steaming Logistics study has explored how the shippers are effected by interviewing six global companies originating in Sweden. The represent both import and export, the manufacturing industry as well as consumer goods and fashion – a wide selection of case companies. The case companies have been interviewed, and gathered for a workshop on the topic. The results from the study indicated that the shippers were firstly affected by slow steaming in 2008 or 2009, and the main indicator has been increased sailing times, that in turn affect their supply chains. The interviews also indicate that reliability can is regarded as more important than the sailing time itself. However, the shippers would like a diversity in the offering in the market for trans-ocean container freight, else other options as airfreight and railroad is considered for supply chains that today utilize trans-ocean containers shipping lines.

The purpose of this paper is to explore research opportunities in Olympic sailing classes. Olympic classes provide highperformance sailing using a diversity of equipment, with the understanding that the equipment, individual athletes, and the knowledge relating to those two factors impacts performance. Thus, the Olympic motto, "Citius, Altius, Fortius" (Latin for "Faster, Higher, Stronger"), governs everyday life for many engineers. During the last few years, Chalmers has supported a project that focuses on the possibilities and challenges for research combined with engineering knowledge in the area of sports. The initiative has generated external funding and gained great acclaim within Chalmers, among staff and students, in the Swedish sports movement, and in large companies, as well as within small and medium sized enterprises. The project focuses on five sports: swimming, equestrian events, floorball, athletics, and sailing. The contribution from this paper describes an outlook identifying eight areas containing research opportunities: sailing dynamics, how to sail in Olympic classes, fluid structure interaction, surface structures, turbulence induction on the rig, equipment in Olympic classes, and applying game theory to sailing.

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.

The purpose of this paper is to explore research opportunities in the Olympic sport of rowing. While innovation in equipment is promoted in rowing the FISA rules don’t allow for it to be a deciding factor in the performance outcome for an individual crew. Thus, the challenge is to look at innovative ways to develop these abilities within a boat and harness their energy to create the most efficient and effective machine. This paper describes an outlook identifying four areas containing research opportunities with an emphasis on being able to ’fine tune’ the moving parts of the engine that is a rowing crew: Sonification in the learning of motoric movement, rowing dynamics that will impact the hydrodynamics around the hull by inducing pitch and heave instead of forward propulsion, surface structures and finally objectivity in on water performance. A research outlook is made into different research opportunities in Rowing, using a coaches perspective. Another novelty is the comparison of the work carried out by the athletes in the rowing to the situation in production systems with assembly operators working at assembly workstations, opening up an new area of well-established theories to by utilised in sports. 

The purpose of this paper is to increase the understanding of how the materials exposure impacts the workstation conditions, in terms of non-value adding work, the space needed and ergonomics. In a typical workstation in the Swedish Automotive industry materials for manual assembly are exposed along the line in pallets, being supplied by forklift trucks. In this study, three workstations were re-designed, using the principles of lean production, one was subsequently rebuilt and a pilot study was performed. Materials had previously been supplied and exposed in pallets and the re- design with smaller containers decreased the space needed along the line with 67%. The results included a decrease of the non-value adding work at the workstation of 23%. The walking path for the operator was decreased by 52%. Reducing picking of unbeneficial exposed materials, unnecessary movements and carrying work improved the ergonomics for the operator.

Transportbranschen står inför stora utmaningar på grund av de negativa miljöeffekter som vägtrafik genererar. För att utreda problematiken med att landbaserade transporter bidrar till tidigare nämnda effekter är godsflödet in till ett köpcenter en intressant fallstudie på grund av godsflödets storlek och komplexitet. Ett köpcenter består av ett stort antal affärer och butiker med individuella transportlösningar, vilket leder till att transporter av gods frekvent anländer till köpcentret. Ett köpcenter där ovan nämnda problematik återfinns är Torp utanför Uddevalla, vilket består av cirka 70 butiker och restauranger samt ett antal större friliggande varuhus. För att förstå transportstrukturen är det viktigt att kartlägga det inkommande godset med avseende på med vilken leveransfrekvens och leveransstorlek transporterna ankommer, vilket transportmedel som används samt varifrån godset kommer. Syftet med detta paper är således att kartlägga dagens transportsystem och förklara de krav som påverkar dagens transportsystem. Resultaten visar att det viktigaste för aktörerna på Torp i samband med leveranser är hög leveransprecision och således vetskap om exakt tidpunkt när leveranserna anländer. Tre viktiga faktorer som påverkar systemet är dessutom (1) automatisering och digitalisering av logistikprocesser, (2) ökad samverkan för samskapande av värde samt (3) yttre påtryckningar med anledning av ökad miljömedvetenhet.

Manual picking on assembly lines is an important part of the assembly operator’s work. In the automotive industry, alternative material exposure strategies are continually evaluated in order to facilitate the assembler’s work and minimise non-value-adding time, resulting in increased use of smaller bins or containers at workstations, instead of large pallets. The assembly operator’s retrieval of components from bins, containers or pallets is known as manual picking. Previous work in this area has focused on picking from pallets placed on the floor; therefore, there is a need to include other forms of material exposure. The purpose of this paper is to explain what material exposure factors have an impact on manual picking times on assembly lines. A full factorial experiment, testing seven factors in 128 experiments, was conducted in an automotive assembly line setting. The factors with the greatest impact on manual picking time were packaging type; angle of exposure; height of exposure; and part size. This study contributes by addressing the importance of six factors influencing manual picking times, enhancing knowledge derived from MTM and elsewhere. The results from this study can be useful for designing manual picking operations, not just at assembly lines but also other situations where discrete manual picking occurs such as at workstations or bench assembly. Managerial contributions are evident in the examination of factors important in designing new production systems, including materials supply processes and assembly processes. A further managerial application is the use of the results in managing assembly lines.

This paper examines how the choice of materials exposure impacts workstation performance, in terms of non-value-adding work, space requirements and ergonomics. In a typical Swedish automotive setting, components are exposed in wooden pallets with frames beside the assembly line and supplied by forklift truck. In a case study, three workstations on an assembly line were studied and redesigned following the principles of lean production, using smaller plastic containers for the materials exposure. After the redesign, the space required for materials was reduced by 67%, non-value-adding work decreased by 20%, and walking distance was reduced by 52%. Furthermore, the ergonomics for the assembly operator improved greatly, with a 92% reduction of potentially harmful picking activities, thereby almost eliminating potentially harmful body movements. The theoretical contribution of this paper is firstly the development of an analysis model describing the impact of material exposure on workstation performance and secondly development of the existing categorisation of work operations to include different materials handling activities. The most important managerial implication is an increased understanding of the relationship between space, ergonomics, non-value-adding work and materials exposure. These findings have direct implications on workstation design in industry.

Sailing is a sport and activity that takes a long time both to learn and to master, as much of its competence-based knowledge is acquired through experience. Experiencebased learning is very important, time-intensive, and the factors for success are often tacit and hidden. Should these success factors become explicit and salient, learning would occur faster and produce obvious competitive advantages. This research was conducted by embedding on-going research results into two competitive sailing teams racing in different classes, one offshore keelboat racing with a crew of eight, and a one-design Star-class racing yacht with a crew of two. The data collection consisted of observations, interviews, and video recordings. The results were also verified with the crews to catch biases in the analysis process. A jibe, a specific but common maneuver was analyzed from the perspective of Common Ground within Joint Activity. Maneuvering a competitive offshore sail racer or a previously Olympic Star-class yacht are tasks that fulfill the requirements for Joint Activity. A high level of Common Ground is required for the effective coordination needed in order to perform at a high level and maintain the safety of the crew and equipment. Breakdowns in the coordination of maneuvers were observed, although they must be recorded on video for higher analysis reliability. To achieve greater validity, more and different maneuvers should be considered within the analysis. By better understanding the factors for success, sail racing teams can more quickly gain competence and thus competitive advantages. The research analyzes the teamwork found in sailing from the perspective of Joint Activity and Common Ground and provides insight into how to achieve performance improvements more efficiently. 

The unit loads, e.g. plastic containers or EUR-pallets, used in an assembly plant can have a significant impact on time efficiency, and hence cost, of both the materials supply and the receiving assembly stations. Smaller unit loads can reduce the time the assemblers spend fetching parts. However, larger unit loads result in fewer moves for a given volume of materials, which implies efficient in-plant materials supply. The current paper explores how the time efficiency of in-plant materials supply is affected by the size of unit loads. Based on the case study, it is clear that the efficiency of the in-plant materials supply is not proportional to the size of the unit loads. There are fundamental differences between how large pallets, compared to smaller unit loads, are delivered, meaning that the increased delivery frequency required for smaller unit loads does not necessarily result in an increased man hour consumption.

The unit loads, e.g.; plastic containers or EUR-pallets, used in an assembly plant can have a significant impact on time efficiency, and hence cost, of both the materials supply and the receiving assembly stations. Smaller unit loads can reduce the time the assemblers spend fetching parts. However, larger unit loads result in fewer moves for a given volume of materials, which implies efficient in-plant materials supply. The current paper explores how the time efficiency of in-plant materials supply is affected by the size of unit loads. Based on the case study, it is clear that the efficiency of the in-plant materials supply is not proportional to the size of the unit loads. There are fundamental differences between how large pallets, compared to smaller unit loads, are delivered, meaning that the increased delivery frequency required for smaller unit loads does not necessarily result in an increased man-hour consumption. 

A ship’s productivity is measured by the number of loaded days at sea. Time in ballast, time off hire and port time are the three main factors that influence productivity. Since the tanker segment has limited possibilities for backhauls, it is common that time in ballast accounts for about 50% of their annual voyages. Time off hire depend on the time spent on essentials as repair and surveys, and of course conditions in the freight market. The overall shipping industry suffers from a continuous imbalance of supply and demand (Stopford, 2009). The last couple of years has been challenging, as new external factors makes demand less predictable (Bellemare, 2017). For the tanker industry, 2015 was probably the best year since the market crisis in 2008 (UNCTAD, 2016, p. 57). However, in 2016, the fortune faded (BIMCO, 2017). Time use at port is the last factor to influence productivity. As an element that is to some extent controllable, port time is a central and widely discussed topic. The functions of a port are crucial for a ship’s productivity. Especially since port charges are a major part of a ship’s voyage cost (Stopford, 2009). As a part of the Interreg project - NØKS II (Nærskipsfart i Øresund / Kattegat/Skagerrak), this research addresses the topic of port time. NØKS II focuses on facilitation and development of sea transportation in a specified area. The aim is to evolve an attractive, environmental, safe and sustainable freight flow between Norway, Sweden and Denmark (Vestfold Fylkeskommune, 2015). This study has been conducted based upon analysis of AIS-data from the year 2016. The total amount of time the vessel that arrived or departed from the selected ports are measured and classified as active or idle time. The majority of the idle time is when the vessel is entering the anchorage area which means that the idle time occurs under an “inward voyage”. The fact is that more than two vessels are often calling to a refinery at the same time, thus the build-up starts. Every ship owner or charter want as many sailing days pr. ship since this when they are making their money, not when the ship is at anchor, also known as idle time. The paper presents the extent of idle time in oil ports by the use of AIS data. The study is performed on two ports, one in Sweden and one I Norway. The paper presents a comperative study between ports in Norway and Sweden.  In Sweden the choice of port landed on Brofjorden, an oil port owned by the largest fuel company in Sweden, Preem AB (Preem AB, 2017). In Norway Slagentangen refinery owned by Norwegian Esso was selected.

This paper is assessing the need to find a tracking technology that can be applied in an alpine location, tracing cross country skiers as well as downhill skiers. The technology used is the differential Global Navigation Satellite System (DGNSS), a high accuracy positioning technology. The basic GNSS uses several satellite navigation systems, always providing good position coverage. The differential part adds more accuracy by using a precisely surveyed reference station. Thereby the tracked object is given a correction signals obtaining a higher accuracy on positioning data. The technology demonstrates the capability deliver accurate data, but there is a need explore the use for continuous tracking of an athlete.

Previous swim start studies involving electromyography (EMG) consistently comprised unilateral measurements and the attachment of the swimmer via cables to a computer. Therefore the present work aims for an overall picture of the muscle activation pattern during the swim start by conducting bilateral measurements with minimal restriction of motion. On that account a multichannel surface EMG device with a wireless Bluetooth connection and videography is utilized in order to assess the nowadays most common start dive techniques of competitive swimming events - differently weighted track starts from the OMEGA OSB11 starting block. The data analysis identified that the normalized muscle activation levels were higher during the front-weighted than during the rear-weighted start - probably caused by shorter block times and less contribution of the arms. Furthermore the onset of the muscle activation seems to be different in between start dive techniques, as for instance the muscles of the rear leg commence contracting earlier while the muscles of the front leg start later in the rear-weighted compared to front-weighted starts. It is highly likely that this originates in the position of the center of mass relative to the muscles. A general overview over the coordination of the different muscles could also be obtained: It became obvious that some muscles are the main drivers of the swim start (vastus lateralis, soleus) whereas others rather exerted supportive actions (gluteus maximus, semitendinosus, erector spinae longissimus).

The study presented in this paper aims at investigating, from a hydrodynamic point of view, the most favourable attitude of a sailing dinghy. The procedure includes both an experimental and a numerical approach. Of interest is if these two methods gives analogous results in terms of resistant force and optimal attitude. The numerical study extends to investigating the effects of adding appendages and leeway to the computational model. As this addition strongly affects the computation attitude can be predicted this way and thus be discarded from future studies of this kind. The included verification and validation study reveals that the resistance is greatly under predicted by the numerical method. Furthermore a complete set of results from the numerical predictions was not obtained which makes the goals of the study unfulfilled. This paper also suggest future work on the topic of sailing. 

PurposeExplicit descriptions of studied systems can support researchers in clarifying objects of study and motives of research as well as in structuring research design. However, since many scholars of systems approaches operate outside the field of logistics, applying systems approaches in logistics can be challenging. The purpose of this paper is therefore to describe how a systems approach can be applied in logistics so as to provide guidance for logistics researchers in their descriptions of studied systems.Design/methodology/approachTwo systems approaches were used to describe the systems studied in six doctoral theses. A series of workshops was conducted to compare the descriptions and share challenges.FindingsKey aspects for adapting the selected systems approaches corresponded to four areas of logistics—activities, flow, performance, and actors—all of which can be included in the selected systems approaches. Advice for doctoral students on applying these frameworks is provided.Research limitations/implicationsThis research can provide support to other logistics researchers when applying systems approaches and developing explicit descriptions of studied systems.Original/valueSystems approaches are central to logistics research, a field in which scholars are encouraged to apply well-known systems approaches. This paper contributes value by providing explicit examples of how such approaches were applied in six logistics research projects.

The purpose of this paper is to investigate whether the minima in hydrodynamic resistance can be predicted to occur at the same angles of heel and trim in the case of bare hull towing tank tests, bare hull simulations and appendage and leeway simulations. If so, the appendages and the leeway can be rejected from future investigations, which would prove a beneficial advancement, as they impose further complexity to simulations. The results of verification and validation (V&V) included in this paper demonstrate that the numerical method predicted too low resistance. Though the study identifies and systematically investigates possible sources of error, the major source of error was not found. These various possible sources of errors were identified for further research, and as future references for similar cases. Moreover, the simulation results for the variations of heel and trim also require further study. Before a full set of results is available, one cannot make conclusions regarding the angles of heel and trim that lead to minimal resistance. This paper discusses the results and potential avenues of future research, and is a result of an initiative at Chalmers University of Technology focusing on sports and technology.

The performance of three bulb keels is compared with that of a traditional fin keel. Hydrodynamic data from wind tunnel tests are used in a velocity prediction program (VPP) with the keels fitted to a 40’ cruising yacht. Two scenarios are investigated: keel retrofitting and new design. In retrofitting, the sail, mast and rig are unchanged, while in new design they are varied to obtain a constant heel angle (Dellenbaugh). Three keel materials are considered: cast iron, lead or a mix thereof. As expected, the bulb keels are superior to the fin keel in all but the lightest winds in the retrofit scenario. The differences between the bulb keels are small, but the keel with a bulb integrated with the fin is slightly slower than the keels with more distinct bulbs, in either L- or T-configuration. These are very close in retrofit, but the T-configuration has a slight advantage in the new design scenario.

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.

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. 

In April 2017, a foiling Optimist dingy designed entirely by students, was successfully tested under standard sailing conditions in the waters outside Gothenburg. In order to achieve take of wind speeds as low as 6 m/s, a stiff and lightweight design of the dinghy and its foiling components was necessary. There have been few successful attempts to make an Optimist foil in a stable manner, as such there were no standards or recommendations available for the design. Therefore, a simulation driven structural design methodology for hydrofoils, centreboards, centreboard-to-hull connections, and necessary hull reinforcements using sandwich structures was adopted. The proposed design was then manufactured, allowing for a significantly stiffer hull and a 20% decrease in weight over a conventional Optimist. Excluding the rig and sail, the final weight came to 27 kg.

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.

As the Laser Olympic dinghy is one of the highest-level sail racing classes in the world, there is an interest in obtaining physical facts around the experience that already exist. For this reason, a numerical investigation has been carried out to find the best heel and trim angles in upwind sailing. Flat water is assumed. The core of the work is a newly developed Inverse Velocity Prediction Program (IVPP) that computes the required wind speed for a given boat speed. Input to the program is both available towing tank data and CFD results. By keeping speed constant interpolation is avoided in the very non-linear resistance-speed relation, reducing considerably the required number of CFD computations. Another reduction is obtained by a special technique for avoiding interpolation in leeway. Systematic CFD computations are carried out to find the optimum trim versus heel at the speeds 2, 3, 4, 5 knots. Using this relation the required wind speed at the four boat speeds can be expressed as a function of heel only. The heel angle corresponding to the smallest wind speed is the best. Knowing this, and the corresponding optimum trim, the position of the sailor is computed. It turns out that the predicted best positions correspond well with practical experience. However, the results highlight the benefit of a small heel in higher winds, which often is regarded as undesired by sailors.

As a follow up to the Olympic Games, commercially available Finn dinghy rudders were tested to determine their hydrodynamic performance. Seven rudders were tested, out of the nine different rudder models that were measured for competition at the 2016 Olympic Games, thus representing a large portion of the rudders used by sailors. The remaining two rudder models could not be tested, since they are of semi-custom or custom design or manufacture. Each rudder was tested in seven different conditions, selected to cover a wide range of sailing conditions. The testing revealed considerable differences, both in performance and handling.

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.

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.