Crest of the Royal National Institution of Naval Architects - Click to return to the homepage



Marintec_New_July_December 2022


Palfinger August 2022

Wind Propulsion 2021 Abstracts

Strengthening the Business Case for Wind Assisted Ship Propulsion

Z Rafaelova, L Pomaska, V Kosmas and M Acciaro, Kühne Logistics University

Wind assisted ship propulsion (WASP) technologies are an innovative option for decarbonising the maritime sector while benefiting ship-owners through bunker savings. As key industry players have started exploring the operational effectiveness and implications of WASP technologies, this article focuses on the factors affecting the business case for WASP. The paper makes use of secondary data following a workshop with industry experts (e.g. ship-owners, associations) and primary data obtained from interviews conducted with four shipping companies engaged in the installation of different WASP technologies. The main motivations driving shipping companies to invest in WASP technologies relate to the potential fuel consumption reduction, the enhancement of their brand value and their green agenda. The technological uptake can be accelerated through the provision of incentives by policy makers either in the form of subsidies, carbon tax or other forms of regulation. Customers can also push companies towards such investments within the context of greening their supply chains. Technical, operational, and financial risks differ according to each WASP technology and require further study from an operational perspective. The uptake of WASP technologies also benefits from a effective decision making within a shipping company, entailing honest communication between technical experts and top management. Furthermore, the paper discusses the important role of the crew, and in particular their additional training needs, as well as of insurance brokers and classification societies, who also play a critical function in the rapid adoption of WASP technologies.

Performance prediction and design of wind-assisted propulsion systems
F Tillig and J W Ringsberg

Wind-assisted propulsion is seen as one of the main alternatives to potential reached large emission reduction in shipping. However, wind-assisted propulsion introduces new challenges in the design, retrofitting and performance prediction of ships as well as the analysis of their performance.

This paper presents and compares methods to predict the performance of wind-assisted propulsion which have been developed in the research project ShipCLEAN funded by the Swedish Energy Agency1. Focus is on evaluating the difference between 1 degree of freedom (1DOF) and 4DOF methods as well as the impact of aerodynamic interaction effects in between multiple sails. Practical design considerations and performance differences are discussed based on three example ships and multiple sail types. Some of the examples are related to the ongoing EU Interreg project WASP – Wind Assisted Ship Propulsion2.



Estimating the Cost of Retrofit for Shortsea Vessels
O Schinas,

The aim of this paper is to estimate the cost of retrofit of shortsea vessels. Operational data and evidence suggest that wind-assisted technologies can result in drastically improved performance in relatively smaller ships, such as those engaged in shortsea and coastal operations. Considering first results and work conducted within the framework of WASP project, this paper aims at estimating the total sum of retrofit broken down per ship type as well as to estimate the financial gap vis-a-vis currently available sources.

A CFD Study on Wind Assisted Propulsion Technology for Commercial Shipping
W C P Hopes, D R Pearson and J E Buckingham, BMT Defence and Security UK Ltd
Wind assisted propulsion has the potential to significantly reduce emissions from global shipping, with a range of technologies available including wing sails, kites, Flettner Rotors, and Suction Aerofoils such as Turbosails. Despite this, there are only a few studies publicly available on the performance of Suction Aerofoils, which operate on the same principle as a traditional sail but use boundary layer suction to develop high lift coefficients. Therefore, a CFD study was carried out in Numeca FINE/Marine software to determine values for the lift and drag coefficients over a range of angles of attack and suction levels. Supplementary studies also investigated the effects of introducing an endplate to reduce end vortices, and the effect of a ship side on the wind speed incident on the Suction Aerofoil. The plots of lift and drag coefficients developed in this paper were used to inform the BMT-led VTAS project [1], as well as contributing to wider knowledge on wind assisted propulsion for shipping. Throughout the study, Suction Aerofoils continued to show promise as an effective means of auxiliary propulsion for ships, and their use should be encouraged as part of the range of solutions to tackle the pressing issue of climate change.

Development of a 1:30 scale sailing model of Oceanbird
A Hillenbrand, KTH Royal Institute of Technology

The wind powered car carrier project launched by Wallenius Marine AB together with KTH Royal Institute of Technology and SSPA AB aims at developing a fully sailing car carrier, known as Oceanbird. The full-scale ship will be about 200 m long and wind powered using 4 to 5 wingsails, with a total area about 10 times the wing area of an airbus A380. Such tall rigs have never been installed on ships and pose many challenges in terms of control, but also offer many opportunities, e.g. with their effect on maneuverability. In order to evaluate different control algorithms, maneuver strategies and to present the appearance of a sailing car carrier, a 7 meter model (scale 1:30) is developed at KTH Royal Institute of Technology and has been successfully tested with 4 wingsails during the fall 2020. The development of the vessel was part of a naval design course where students had to conceive, design and implement solutions to turn an empty hull into a fully sailing boat. The main characteristics of the model are presented in this paper together with the initial results of tests that took place in Stockholm's archipelago.

Appendages investigation in IMO manoeuvres for wind propelled vessels
L Marimon Giovannetti, SSPA

Assessing the manoeuvring performances of a ship early in the design stage is becoming ever more important, especially now that wind-assisted propulsion is radically increasing in popularity as a measure to reduce fuel consumption. For conventionally propelled vessels most of the forces are in the longitudinal direction. Some, relatively small, drift angles and rudder angles are encountered in order to compensate for side forces due to environmental conditions. For a wind-propelled vessel on the other hand, side forces and yaw moments are an inevitable consequence of the propulsion choice and it is of utmost importance to balance this force/moment with a matching hydrodynamic design to efficiently propel the vessel forward avoiding travelling for longer periods of time. In order to counteract large side forces, it is necessary to add underwater appendages. Their position along the hull will determine the centre of lateral resistance (CLR) that needs to be related to the aerodynamic centre of effort (CoE) in order to achieve a balanced ship. The research developed within SSPA, assesses the differences arising during a dynamic IMO manoeuvre for a hull with rudders and the effects of adding different appendages on the manoeuvring performances, which doesn't necessarily match the expected quasi-static VPP outcome.

A Review of Wind-Assisted Ship Propulsion for Sustainable Commercial Shipping: Latest Developments and Future Stakes
L Khan, J J R Macklin, B C D Peck, O Morton, and J-B R G Souppez, Aston University

With the current global warming crisis and contemporary concerns for sustainability, the transport industry, led by the automotive field, is developing and implementing novel solutions to reduce greenhouse gases (GHGs). With close to 90% of the world’s goods relying on maritime transportation, primarily via cargo ships, responsible for 2% of global energy-related CO2 emissions in 2019, there is a vital emphasis on reducing emissions. The latest legislation from the International Maritime Organisation (IMO) has imposed tougher sulphur oxide targets, 0.5% m/m down from 3.5%. On the other hand, emission intensity for CO2 will need to be decreased by 70% in 2050, compared with 2008 figures. While propulsion and fuel alternatives are suitable in the short term to meet these novel regulatory constraints, as the use of fossil fuels tapers off, the long terms solution appears to reside in wind-assisted ships.

Consequently, this study aims to identify viable solutions that could reduce emissions and analyse potential savings. Building on existing work, three prominent technologies will be tackled, namely kites, sails and rotors to ascertain efficiency for a given ship along a variety of shipping routes. In addition, commercial aspects such as installation and maintenance costs, ship capacity, and crew training will be considered. Furthermore, this review will provide guidance on the benefits and risks associated with each technology as well as highlight the opportunities for performance enhancements using numerical methods, particularly computational fluid dynamics (CFD), ultimately providing a comparative assessment of present options and identifying future stakes in wind-assisted propulsion.

Methods of Retrofitting Wind Assist
A Johnson, Dasivedo Design Ltd

There will be no single solution to the challenge of replacing hydrocarbon fuels in shipping. The basket of technologies deployed will include wind assist (WA). WA is delivered free at the point of use and will be a part of ship propulsion for the rest of time. WA is a virtually no risk, future proof investment compared to alternative fuels that might be superseded.

Because of the age of the world's fleet and their expected lifespan shifts to non carbon fuels cannot wait for new build ships. Like other alternative fuels WA can and must be retrofitted to existing vessels.

This paper examines the handful of current suggested methods of deployment/mounting.

1. dedicated masts at the bow of ships used to deploy kite sails by Skysails, Airseas and others

2. deck pads used by Norsepower for their Flettner rotors and BAR for their sails

3. a deck rail system used by Anemoi for their Flettner rotors

4. plug in deck mounts suggested by Smart Green Shipping Alliance

5. container-deployed systems used by Wind + Wings, Econowind and others

6. the Tig Rig's side of the hull mountings.

The paper briefly describes each mounting and assesses their advantages/disadvantages. The paper reports back on industry thoughts on each of these technologies. It examines the possibility of multiple WA deployment per ship and speculates on each system's likely industry wide take up and long term viability; how future proof they will be.

Experiences of Rotor Sail installations on various ship types and the emission reduction potential of Rotor Sails
J Kuuskoski, Norsepower

Norsepower has delivered and installed Rotor Sails on a variety of ship types. The paper describes the technical and operational requirements for Rotor Sail installations on tankers, roro-vessels, ferries and bulkers. Third-party verified performance results are presented as well as customer feedback on how the Rotor Sails are viewed by the ship’s crew. Operational requirements such as air draft restrictions and cargo operations can be complied with by applying a tilting Rotor Sail. Aspects related to tilting Rotor Sails and the first experiences from installations are described. The global shipping community faces enormous challenges in finding feasible and proven solutions to reduce their environmental impact and specifically fossil fuel related emissions. The paper discusses wind propulsion technology’s potential to be a significant part of the emission reduction solution in today’s ship designs.

Sea keeping model testing of wind powered vessels
S Werner, SSPA Sweden AB

Assessing the sea keeping performance at design stage is even more important for wind powered ships than for conventional ships, since there is so far little experience to lean on. When the driving force comes from sails instead of a propeller, the ship's dynamics changes considerable. Corse keeping ability, turning ability, motions and acceleration in waves are some properties that must be assessed. However, including wind propulsion devices in a model test is not straight forward. The study will present a methodology for model testing of wind powered vessels applied to a car carrier. The results are based on recent tests carried out at SSPA. Challenges of the test methodology and the possibilities to draw useful conclusions from the tests will be discussed.

Rondout Riverport 2040 A Post Carbon Gateway to the Hudson Valley and the World
A Willner, The Center for Post Carbon Logistics

Rondout Riverport 2040 proposes a pragmatic and prosperous vision for the near future with a transformed port, boasting a shore lined with leading-edge and heritage maritime commerce that profit and engage while allowing for an equitable transition beyond fossil fuels.
Rondout Riverport will offer more capacity, be significantly more compact, and more resilient than the current patchwork of land uses found on today's waterfront. The mission of tomorrow's port is the post carbon maritime transport of goods and people up and down the Hudson River and beyond. Riverport is designed to attract shipping, distribution, commerce, food processing, and craft businesses. The result: a regenerative working waterfront — a gateway to the Hudson Valley and world.
The port's versatility will depend on the linking of its economic opportunities with environmental restoration, sustainable commerce, and training centers. This multi-generational project will also be a source of inspiration for broader long-term action on climate change.
We can best accomplish these goals using "placemaking," answering critical questions: What are the best ways to mobilize and coordinate our many community assets? How do we effectively draw on public and private partnerships to identify opportunities? How can we successfully coordinate our implementation efforts? And where do we find the resources needed to accomplish our vision for a transformed Riverport?
The path to a regenerative future starts with community engagement and data collection, planning, and implementation of an actionable vision, one that incorporates a sense of community and place, local stewardship, and widely shared economic opportunity.

Wind technologies in shipping to 2050: Factors and challenges for a sustainability transition
J Köhler, E Dönitz, Fraunhofer ISI 
F Schätter Hochschule Pforzheim

This paper presents a scenario for a transition to low carbon shipping. It combined a structured scenario process and simulations with the MATISSE-SHIP model to develop consistent qualitative and quantiative scenarios, agreed with sector experts. The IMO decides a binding target to reduce GHG emissions by 90 % by 2050. The use of LCF technologies for shipping, such as PtL/PtG, H2 fuel cells, and wind technologies, becomes the state of the art. Rapid action is required by the shipping sector. If society is willing to prioritise reduction of climate change, new operational patterns in shipping are possible. This behavioural change needs to be supported by strong climate policy to force the rapid development and adoption of wind and other low carbon technologies.

Interactions between Two Flettner Rotors used for Wind Ship Assisted Propulsion
B Charrier, Consultant

Wind tunnel tests are carried out at the Aerodynamics Laboratory of the Ecole Nationale des Arts et Métiers (ENSAM) in Paris on 50 mm and 130 mm diameter rotating circular cylinder in infinite aspect ration or finite aspect ratio of 3 to 6, with or without rotating endplates. Aerodynamic forces are measured by a 5-components balance and by integrating pressures over three sections along the span of the rotating cylinder. In this publication, only the results obtained for speed ratio k = U/V (ratio of the peripheral speed of the cylinder to the speed of the flow measured in the wind tunnel), greater than 1.5, are considered, allowing to be free from the inversion effect of the Magnus effect. For the first series of measurements, the forces are measured with an aerodynamic balance on a rotating cylinder of 50 mm of diameter in infinite aspect ratio and finite aspect ratio of 6, 5, 4, 3 and 2, equipped or not with rotating endplates to cylinder ratios of De/D=2. Comparisons with the work of Badalamenti (10) and Bordogna (11) and other authors show that tests carried out at Reynolds numbers between 13,500 and 70,000 are significant and make it possible to dispense tests at high flow speeds. The second set of results, based on pressure measurements on a 130 mm cylinder, indicates that the rotation of the cylinder drives the fluid in a spiral motion along the span, winding the flow, accompanied by a very strong increase in the drag coefficient between the middle and the top of the cylinder. For example, in infinite aspect ratio and for k = 2.5, the drag coefficient CD goes from 0.7 in the middle of the cylinder to 1.7 at the top. The lift coefficient CL remains practically constant at 7.4. The impact of this winding effect on CD increases with the k coefficient. On the other hand, CL is only slightly affected by this winding effect of the flow when k increases. Only the measurement of the overall aerodynamic forces, with an aerodynamic balance and not with the pressure measurements, makes it possible to integrate the impact of this winding effect on the entire rotating cylinder. The third series of results is carried out with two cylinders of 50 mm of diameter, fitted with rotating endplates, spaced out by 6 diameters, rotating at the same speed and in the same direction, placed on an axis whose angle β with the apparent wind varies from 0 ° to 180 °. The effect on the upstream cylinder by the downstream cylinder is reduced, conservation of CL regardless of the angle β and variation of CD from 5 to 10%. The downstream cylinder is in a flow largely modified by the upstream cylinder. The CL varies from 5 to 10% depending on the value of the angle β, the CD increases by 100 % for β = 30 ° compared to the CD of the cylinder alone. The value of CD of the cylinder alone is found for β = 150 °. The interaction between two rotating cylinders decreases the ratio CL / CD of the thruster reducing its propulsive performance at close wind angles (30 ° <β <70 °).

Speed Trial Verification for a Wind Assisted Ship 
S Werner, SSPA Sweden AB

As the number of Wind Assisted Propulsion installations in commercial shipping grows and the industry matures, the need for methods for verifying the performance in full scale is increasing. However, no standard or guideline is available today. The paper discusses several ways to conduct and analyse a speed trial for wind assisted ship. The methods are demonstrated using a speed trial conducted with Scandlines ferry Copenhagen equipped with a Flettner rotor.

Flettner rotors performances and interactions effects on the MARIN Hybrid Transition Coaster
J Schot, MARIN

In the context of wind assisted ships design, knowing the aerodynamic performance of a ship and its wind propulsors is essential. In the literature, the performance of wind propulsors is generally derived from wind tunnel tests data, full scale tests or CFD database. Those experimental or numerical databases are often omitting the interactions with the ship and its superstructures and atmospheric boundary layer. In this research, a numerical approach using RANS simulations is developed to estimate the effects of the interaction between the MARIN Hybrid Transition Coaster (MHTC) and its three Flettner rotors. In order to assess the effects of these interactions, the performance of a Flettner rotor positioned on the deck of the vessel is compared to the performance of a free standing Flettner rotor. Large interaction effects are found to depend on the apparent wind angle. Accounting for these interactions is essential. A model based on the thrust identity approach, applied in the analysis of ship propellers, combined with a correction for the apparent wind angle is proposed to correct the performance of free standing Flettner rotor to the performance of a rotor on the deck of the vessel. Further work is ongoing to refine the model in order to account for rotor-rotor interactions.

Horses for courses: How to select the “right” wind propulsion system and how to make the business case
F Gerhardt, SSPA Sweden AB

Wind propulsion systems (WPS) are major investments and the decision to install them requires careful consideration of many complex questions. In this paper we present a systematic, scientific methodology to assess the benefits and drawbacks of such systems at the early concept stage of a vessel. The purpose is to provide guidance for shipowners and operators and help them make informed decisions. The proposed method has been correlated to full scale results and draws on our large database of model tests and CFD of hulls and wind propulsion technologies. It uses the intended trading routes of the vessel as an important input, typical output data are: a) performance values (ship speed, power requirements etc.) b) environmental parameters (CO2 avoided, EEDI and EEXI reduction, carbon intensity indicator) c) financial metrics (bunker savings, payback time for installation of WPS, change in time charter equivalent TCE) As the example of a VLCC shows, the choice of the optimal WPS depends on the trading pattern of the ship. Certain systems are more suited for a specific route than others.



Sponsorship & Exhibitors

RINA events provide the perfect opportunity for effective and highly targeted marketing. 

Sponsorship and exhibition opportunities exist for all of our conferences. For more information please follow the link or contact JP Media Services Tel: +44(0)1737 852 135 or e-mail:  to discuss tailored options or availability.

Rina Crest Update

CPDContinual Professional Development

Attendance at the RINA conferences and courses qualifies as Continuing Professional 

Development. On completion of the course a CPD certififcate will be issued.

RINA membership

Teinbridge Propeller

Euronaval Apr - Oct 2022

Herbert Engineering

Uni Stratchclyde June 2021

Metstrade May 2022