The build-up of biofouling on ships’ hulls is an age-old problem for ship operators and the shipping industry. Severe underwater biofouling slows the affected ship and can increase its fuel consumption by as much as 40%, boosting already high CO₂ emissions.
And biofouling doesn’t just slow ships down. The accumulation of marine life may cause the spread of invasive aquatic species in environments they’re transported to, affecting biodiversity, ecosystem health and the livelihoods of coastal communities across the globe. It’s something that regulators, port authorities and conservation bodies are increasingly concerned about.
So it is little surprise that an increasing number of operators are seeking new technologies and solutions to address biofouling and improve hull efficiency. But ship antifouling and hull performance management are complex topics. Millions of dollars are being spent on research and development of new solutions, but it remains a constant challenge for operators and the industry.
Geir Axel Oftedahl, Breakthrough Innovations Director at Jotun Performance Coatings said in the lead up to the combined HullPIC and PortPIC conference that “While biofouling remains a huge challenge, the good news is the adoption of advanced antifouling coatings, better performance monitoring and in-water cleaning standards is on the rise and likely to continue as ship operators push to achieve performance improvements and meet the upcoming environmental regulations.
“At the same time, however, there’s many new innovations and solutions coming into the market and there’s a need to share knowledge, insights and act collectively to address the global biofouling issue. And that is why we meet annually for in-depth, technical talks about developments and the next steps to further improve methods, measurements, analysis and actions,” he added.
Performance monitoring in vogue
Certainly, performance monitoring is very much in vogue and while there is wide consensus that it is necessary and good, there remain issues especially in relation to data quality, sensor failures and baselines according to co-organizer Volker Bertram (DNV).
“Performance monitoring looks simple – at first glance: At a given speed, my ship has a certain power requirement. As the hull accumulates fouling, this power increases, respectively at that power my ship experiences a speed loss. Accordingly, we can measure and express a performance loss. However, it gets complicated due to changing ambient conditions and operational conditions and there’s also a need to consider the “at a given speed” aspect,” said Bertram.
Hydrodynamically relevant is the speed through water (STW) he pointed out, but this is notoriously inaccurate in traditional speed log measurements and as a rule of thumb 1% error in the speed measurement means 3% error in the power. Sensor experts Miros and ship operator BW Dry Cargo joined forces to address this issue. Their new joint venture Miros Mocean seems to have cracked the nut. Using on-board radar to determine waves and currents, they present a convincing approach to get accurate speed through water measurements.
Search is on for accurate and affordable approach
The measured power relation needs to be corrected for changing ambient conditions and then be compared to the ideal power at the given speed, draft and trim of the ship. This ideal condition is known for sea-trial conditions, not even 1% of the operational conditions encountered in reality according to Bertram who emphasized the need for baselines expressing power as function of speed, draft and trim.
“These baselines are used to reconstruct a full hydrodynamic knowledge base from the small reliable fragments that sea trials furnish – one is reminded of the task of reconstructing a dinosaur from a single jawbone. You draw on experience, computer simulations, and fantasy. A frequently quoted maxim in the community is that all models are wrong, but some are useful. And the suspicion, occasionally proven and published, is that some of the baseline models used in performance monitoring systems are wrong and not useful,” said Bertram.
The conference also highlighted that the baseline approach of the default method of ISO 19030 is quite correct and useful but considered by some as too expensive. It would require systematic computational fluid dynamics (CFD) simulations or systematic machine learning applied to the new ship. Hence the quest is on for a cheap and accurate approach.
Two trends giving hope for better models
Long-term, there are two trends giving hope for better models: Firstly, massively parallel CFD computations are becoming more accessible and cheaper, allowing systematic computations for hydrodynamic knowledge bases used both for trim optimization and performance monitoring. Secondly, more and more vendors use data fusion to improve data quality and derive cheaper, yet reasonably accurate surrogate models, as, for example, that presented by Cedric Deymier (Wärtsilä Voyage Germany) who recommends “blending data sources to economically predict hull fouling”.
Irma Yeginbayeva (Jotun) also shared insights on the prediction of antifouling coating resistance using CFD methods for full-ship application. The method involves simulated ship speed ranges and can be used to compare performance of antifouling coatings, in order to understand how they perform differently, and for benchmarking.
While many of the presentations focused on state-of-the-art technologies and methodologies, several of the ship operators, speaking on the sidelines of the conference, made the point that data acquisition and performance monitoring is more than just academics.
Not just for academics
“Getting the best bang for your buck out of the fuel that you burn is key for fleet performance…even when fuel is not so expensive, the drive for efficiency is still very relevant. So, analyzing data and monitoring is important but our experience shows none of the solutions will fit all ships so a strategy for hull management should be ship specific,” argued one operator.
Another operator representative commented, “Some ship operators may have been reluctant to invest in monitoring systems but tightening regulations like the EEXI and CII and future carbon pricing are likely to change their mindset. Real-time analytics of complex data will be key to reduce fuel costs and help demonstrate improvements in their CII and efficiency ratios.”
“The insight gained from performance monitoring is increasingly used to trigger and assess action but even the best and most sophisticated monitoring does not save any fuel,” said Bertram and warned, “Insight without action does not save any fuel, but action without insight is at best inefficient, and sometimes does more harm than good. That said, it is gratifying to see how the industry is moving from monitoring to action, and how much progress is possible with insight-based decisions.”
From insight to action
Several case examples were highlighted during the conference. “Preliminary results indicate that via digital decision support and effective decision support the ship [a small Danish ferry] can reduce the fuel consumption and the emissions with 10-20%”, said Navigator’s Soren V. Hansen. Similarly, service provider GreenSteam and tanker operator D’Amico achieved significant fuel savings, reduced CO₂ emissions and CII rating (A) by using insight from their performance monitoring machine learning models for speed optimization during voyage planning.
But the main application lies in deciding when and how to clean the hull. Here, more and more operators and consultants realize that for commonly used antifouling paints cleaning is a double-edged sword. While directly after cleaning the hull performance is significantly improved, most cleaning methods, however, remove both fouling and paint particles containing biocides and microplastics. This may lead to premature loss of protection, resulting either in massive performance penalties or the costly need for a premature dry-docking to reapply antifouling coatings. Ports and environmentalists are also concerned about release of invasive aquatic species and contamination of port silt.
Debate on in-water cleaning
Again, the consensus is insight is the first step towards improvement. The debate on in-water cleaning and its environmental impact has gained momentum over the past two years. Milestones were Jotun’s Hull Skating Solution and associated guideline for Proactive Cleaning of Hull Areas in Port & at Anchorage and BIMCO’s industry standard on In-Water Cleaning with Capture , both published in 2020.
During the conference Aron Frank Sørensen (BIMCO) shared the aims of the standard and emphasized the importance of knowledge-sharing and supporting a strong quality assurance of the entire cleaning industry. “The standard shall help ensure that the cleaning process is planned, safe and effective, the environmental impact is controlled, and properties of antifouling systems are preserved and that approval of in-water cleaners is internationally accepted.”
Several lines of defence needed
Staying on the subject of in-water cleaning, Runa A. Skarbø (Bellona) informed the audience about the new Clean Hull Initiative (CHI) which is a collaborative project initiated by the Bellona Foundation and supported by Jotun. “We are now in the process of bringing together key industry stakeholders and our objective is to develop an industry-wide recognized and accepted standard for proactive hull cleaning. This will help to minimize the spread of aquatic invasive species via ships and also significantly reduce shipping emissions,” said Skarbø. The initiative comes at a time when the BIMCO standard is in the early stages of testing but Skarbø was quick to point out “no one antifouling or in-water cleaning solution can combat fouling alone – several lines of defence are needed” and argued “proactive cleaning should be part of the biofouling management toolbox.”
Manolis Levantis (Jotun) commented, “As the demands on environmental compliance as well as transparency and efficiency are escalating globally, there’s a need for close collaboration with the industry stakeholders to develop new solutions, adopt new ways of working and standardize best practices.”
Poll reveals mixed opinions
At the same time, the changing regulations, technologies and solutions are leaving many stakeholders confused and uncertain about what the future will bring. During the conference, delegates were asked to complete a questionnaire seeking their views on a number of topics. Organised by Richard Marioth (Idealship) the opinion poll revealed the impact of the impending CII rules was thought by the majority of the attendees to be a factor that will see improvement in the average hull performance. Although more than half thought the improvement would be minor, around 40% thought the impact would be a significant or very significant driver of improvement.
There was a slightly less positive response to the question asking when 95% of ship operators would assess hull performance by data logging. Here 40% thought this would happen between five and ten years from now but 30% believed the time span would be longer and perhaps the 95% level never reached. Even so most of the delegates - 75% - believed high frequency measurements will be extremely valuable in achieving the required CII improvements.
Attendees were also asked to rank in order of difficulty four challenges of shipping companies with regard to improving hull performance. Top of the list was inaccurate measurements and analytics followed by CII compliance. In third position, and perhaps something that will need to be addressed urgently if decarbonization is to be achieved, was the lack of proven retrofit measures. EEXI compliance trailed in fourth position, but it was notable that those putting this as their main challenge also listed lack of retrofit measures high on the list.
When given the choice to list their own suggestions for shipping companies to succeed on CII matters, a wide range of ideas and opinions were submitted. Not surprisingly many of these were related to the need to obtain more accurate data and to do so at high frequencies. Regular grooming and cleaning also featured high. Although perhaps not the most attractive option for ship operators sailing half empty and at reduced speed were mentioned.
Carbon intensity top priority
The “no idea” feedback was probably intended as tongue in cheek answers, but it is likely it resonates with many who are just beginning to grapple with the implications of CII and EEXI. As Vegard Marken (Odfjell Tankers) said, “As a fleet performance analyst I was very pleasantly surprised about the technical level of the presentations – very informative and interesting. Glad to see that so many presentations addressed reduction of carbon intensity, for shipowners this will be the top priority the coming years.”
Commenting on the conference Kostas Korfiatis (Tsakos Columbia Shipmanagement) said, “While the market’s demands for efficiency and sustainability are increasing, the industry’s focus is shifting from maintenance and monitoring to high performance systems and optimization from every possible aspect. Owners, operators, regulators, service suppliers and all related parties have to join forces to achieve the demanding targets of energy efficiency and environmental excellence. The conference was an opportunity to gain valuable insights and gather feedback from different stakeholders on innovations and the latest developments, leading to a very fruitful event.”
“It has been refreshing to receive and disseminate so much information on my topic of interest. Apart from the interesting presentations that were the main focus of the conference, I enjoyed being part of the panel discussion where we talked about logged data quality and its importance to the decarbonization of shipping,” said Angelos Ikonomakis (Maersk).
Klaudio Krpan (Thenamaris LNG) added, “The conferences always provide some valuable information, including from my point of view as I look at things from the owner and ship operator perspective and, I would say, from a practical rather than a theoretical point of view. It was particularly interesting to hear the views on CII and how this will affect owners and operators. The fact is that, despite what we do, we have limited, if that, input on the voyage profile (speed), which is the main contributor to CII. Another interesting topic for me was the study of waves and their influence on ship performance and consumption. Very useful and something that I will use in day-to-day operations.”
Call for the industry to move faster
“In recent times the shipping companies have become more aware of the fouling challenge and the resulting fuel penalties due to vessel performance monitoring systems. This is a step in the right direction but we are not moving forward fast enough as an industry,” said Alex Noordstrand (FleetCleaner) and added, “We need representatives from the regulating authorities to be more involved in the conference to discuss new developments, standards and actions within the industry.”
Contributing her thoughts on the conference, Ditte Gundermann (Hempel) said, “The discussions very much centred on EEXI and CII and I am happy to see the increased attention, however, there are still huge quantification and documentation challenges arising from poor data and analysis methods, which hinder and slow down the implementation of these initiatives. I see the conference as a great facilitator for knowledge sharing that has and will increase understanding and capabilities in the shipping industry and in time will help lead the way for the implementation of new and more energy efficient technologies.”
No one solution that fits all
“At a time when market pressures and regulatory developments are forcing the maritime industry to focus more on energy efficiency and meeting environmental requirements, there are opportunities and challenges in choosing the ‘right’ technologies and solutions to measure and improve hull performance management,” said Stein Kjølberg (Jotun) and added, “There’s certainly no one solution that fits all – the feedback from the industry bear witness to this. Yet, it’s often acknowledged that verifying hull performance and gathering quality data can help operators achieve better performance management and meet regulatory and other stakeholder requirements. The discussion often boils down to: performance management – yes, but how?”
“Clearly, insight-sharing and action is critical to improving performance and protecting the environment. But all stakeholders must be involved if the benefits are to feed through and that’s why we, together with the supporting sponsors, are organizing the annual HullPIC and PortPIC conferences,” concluded Kjølberg.
Taking place in Tuscany recently, the combined Hull Performance and Insight Conference (HullPIC) and the In-Port Inspection & Cleaning Conference (PortPIC) conference attracted some 60 participants in person and others joining via Teams to make presentations and join in the debates.
Due to travel restrictions caused by the COVID pandemic, the 6th HullPIC had to be shifted and the opportunity was taken to merge it with the 2nd PortPIC. Combining the two events turned out to be a blessing in disguise, as the two communities have much potential for cross-fertilization.
HullPIC has its focus on insights into hull and propeller performance, using assorted sensor data, noon reports and increasingly machine learning to determine the current status of energy efficiency. Meanwhile PortPIC has its focus on in-water cleaning, the action to improve the performance of hulls, but which is subject to scrutiny and constraints from assorted stakeholders, especially port authorities and environmental agencies.
Even if the effect of the pandemic is still palpable, the spirit in the industry is noticeably more optimistic than last year and attracted a wide range of industry stakeholders including ship operators, technology developers, equipment suppliers and data analysts. In all around 30 presentations were made covering a wide range of topics and from a diverse selection of business and academic segments.
Driven by Jotun and DNV, the organizers and supporting sponsors are working together to take a proactive role in shaping next generation hull and propeller performance management and solutions and standards for in-water cleaning.