Come together – if right now is not possible, maybe later. HullPIC 2021 – the 6th Hull Performance & Insight Conference had to be shifted, due to Covid-19, and was then merged with 2nd In-Port Inspection & Cleaning Conference (PortPIC). By Volker Bertram
The sister conferences are jo[ds_preview]ining forces exceptionally this year. This may in fact 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 – one could say the ultimate EEXI decreasing in time with biofouling.
Meanwhile PortPIC has its focus on in-water cleaning, the action to improve the performance (ideally back to its original state), but subject to scrutiny and constraints from assorted stakeholders, foremost port authorities and environmental agencies. In essence, we have insight and action for ship performance. And who would argue that having the two combined, at least on occasion, is a good thing. Insight without action is just as bad as action without insight. »Build it and they will come,« said Geir Axel Oftedahl from Jotun, the initiator and mastermind behind the concept of HullPIC back in 2016, and more recently, PortPIC. And indeed, they do keep coming (together) – people, companies and technologies, even if the effect of the pandemic is still palpable.
Simple at first glance
Some key countries like Australia and New Zealand have lock-down policies in force until the end of 2021. Some companies are struggling for survival or have already sadly folded their cards, at least in the business segment of interest at HullPIC and PortPIC. But the spirit in the industry is noticeably more optimistic than last year, and most of the traditional participants have announced their participation for the events planned from 30.8. to 1.9.2021 in Tuscany, Italy.
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. Before we complicate the matter by looking at changing ambient conditions and operational conditions, let’s go back to the beginning »at a given speed«. Hydrodynamically relevant is the speed through water (STW), 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.
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. We then need »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 aphorism 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.
Getting closer to the holy grail
The baseline approach of the default method of ISO 19030 is quite correct and useful, but too expensive for most users in the industry. It would require systematic CFD simulations or systematic machine learning applied to the new ship. Hence the quest is on for a cheap and accurate approach. And in this quest, many fail – but that is no proof that we may not have reasonable accuracy for much lower effort. Sometimes semi-empirical methods work surprisingly well for ships, even if the theoretical base is questionable.
I like to compare such methods to a knitted pullover – hole to hole and yet it holds. Richard Marioth from Idealship calls it »improving true lies – creating sophisticated baselines out of woefully little«. The short-term solution for some vendors seems to lie in avoiding looking too closely at just how high the errors in the model are at intermediate load conditions where bulbous bows pierce the water surface and massive wave breaking renders tradition ship design methods useless.
Two trends giving hope
Long-term, there are two trends giving hope for better models: (a) 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. (b) more and more vendors use data fusion to improve data quality and derive cheaper, yet reasonably accurate surrogate models, as e.g. presented by Daniel Schmode from Wärtsilä Voyage Germany who recommends »blending data sources to economically predict hull fouling«. We may not have the holy grail yet, but we are getting closer to it in our quest.
Even the best and most sophisticated monitoring does not save any fuel. Insight without action does not save any fuel, but action without insight is at best inefficient, and sometimes does more harm than good. It is gratifying to see how the industry moves from monitoring to action, and how much progress is possible with insight-based decisions. »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 %«, shares Soren V. Hansen (The Navigator) from his experience. Similarly, service provider GreenSteam and tanker operator D’Amico achieve significant fuel savings 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 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 concerned about release of aquatic invasive species and contamination of port silt.
New industry standard
Again, 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.
Both are milestones, but unlikely to be the final word. Changing requirements and regulations meet new (but often yet unproven) technical options, leaving many stakeholders at a loss. The developments are dynamic in many related fields, not just the operational guidelines: new, non-biocidal antifouling solutions and robotic cleaning technology are just two prominent representatives that will feature at PortPIC. The issues are controversial, and the debate in the community sometimes passionate and heated. Politics, science and economy do not always see eye to eye, especially when venturing into fields where we all lack knowledge and experience – we have all learnt that from the Covid-19 crisis.
At least everybody can agree on two things: (a) The issues are complex and require further discussion and (b) coming together in person is not only an enjoyable, but an effective way to create and disseminate our collective knowledge. They will all come together, at HullPIC/PortPIC 2021, knowledge, insight, technology and people.
