Shipowners soon will have access to data to help assess performance of coatings

1 Coatings

Did you ever wonder if you have truly chosen the best marine coatings and how they are performing on your hull? Soon there will be a lot more quantitative data to help you find out.

Two international frameworks are under development that will enable shipowners to assess the effectiveness of hull coatings and their impact on hydrodynamics and fuel efficiency.

This year, the International Organization for Standardization (ISO) is working on a new standard on the documentation of hull and propeller performance. The guidelines for performance monitoring are expected to include accepted methods of gathering quantitative data relevant to the assessment of hull coatings.

On top of that effort, the classification society DNV GL is developing a system to monitor fleet performance that, for the first time, isolates the impact of the hull coating under real-life conditions in precise detail. The effort, aimed at saving fuel and reducing emissions, is part of DNV GL’s ongoing ECO Insight software solution.  

DNV GL is working with coatings manufacturers Hempel A/S and Jotun A/S to collect and analyze data on hull degradation. Factors to be measured include bio-fouling, coating durability, the roughness or smoothness of the surface, and even the ability of the coating to self-polish in the seawater.
“The most important factor here is fuel efficiency,” said Claes Skat-Rordam, fouling control marketing manager at Denmark-based Hempel. “Fouling decreases the speed and increases the drag or resistance, and this is what you want to avoid. … You can get a double-digit percentage difference in fuel consumption.”

The International Organization for Standardization’s global effort to assess hull and propeller performance is the new ISO 19030 series, currently under review. The existing ISO 16145 series specifically addresses protective coatings and includes standards for the coating work itself, including surface preparation, priming and dry film thickness measurement, plus inspections.

The missing link has been the inability to statistically ascertain the performance of hulls and propellers. The emerging 19030 series is the key that will unlock the ability to quantify the performance of the coatings on hulls and propellers because it will finally deliver universally recognized quantitative performance standards based on real data from ships. 

Over the years, the best that analysts could do to assess coatings and their effect on ship performance was to compare them in relatively short sea trials or on models in an experimental wave tank under controlled conditions. Those efforts usually are too short in duration and can’t replicate sea conditions faced during real operations over time. Plus, operators want to know what is happening on their own ships.

Torsten Büssow, DNV GL’s head of fleet performance management, said there was never enough real information to help shipowners make decisions. 

“The first question is ‘When do I need to clean my vessel?’ and the second question is, ‘Is it worth it to buy the high-performance coating?’ and there is currently no way to determine this,” Büssow said. “There have been attempts to do quantitative computations but there is uncertainty. There was quite a lot of subjectivity.”

Jotun, based in Norway, was the first coatings provider to partner with the ECO Insight project. Jotun’s own Hull Performance Solution can reduce fuel costs and emissions by 16 percent, the Norway-based company said in its 2015 announcement. 

A new dawn of statistical analysis has become possible because modern-day ship systems — propulsion, navigation, fuel monitoring, etc. — now gather so much real-time performance data and report it electronically to shoreside management.

The tanker Cosrich Lake has just received a new coat of a Jotun anti-fouling product. Both Hempel and Jotun are working with DNV GL to gather a new series of performance data and provide analysis to shipowners indicating how long their protective coatings last on hulls and propellers.

Courtesy Jotun

One huge challenge was that, while lots of data has been available to monitor the performance of an engine, it has never been as easy to measure the efficiency of the propeller. DNV GL will use a computational fluid dynamics model that is designed to holistically measure that complete operational range of the hull and propeller.  

Along with the standard engine readings, ships now are gathering a bevy of “big data,” ranging from shaft power, fuel’s calorie value and cargo load to wind, waves and currents. Strategically installed sensors, torque meters and thrust meters can measure even more. In effect, analysts can determine the seemingly non-measurable hull and propeller performance by measuring everything else about the ship’s operations and conditions and then subtracting those from an overall performance equation.

Coatings professionals are interested in measuring average hull roughness and micro-roughness, Skat-Rordam said. 

A draft ISO 19030 framework was undergoing a voting process that was scheduled to conclude in mid-March. The accepted methods will enable analysts to calculate average speed loss over various time horizons, e.g., from one five-year scheduled dry-docking to the next. Then they can figure out the added fuel consumption and emissions. 

With an internationally accepted standard, plus the technological ability to gather more types of data on vessel performance and sea conditions during real voyages, finally there is enough information to assess the effect of the coatings and their deterioration. 

“This will mean that we are able to take measurements of a large number of vessels for our customers and determine how they are performing with different types of coatings,” Skat-Rordam said. “We can measure the hull roughness and we can compare their tendencies to foul.”

In the DNV GL project, the ship-to-shore reporting of all the component performance data is run through a supercomputer in Hamburg. Software sifts it through computer modeling with an eye toward delivering a report that the captain or shore-side manager can use to make money-saving decisions. 

“He will see in a nice-looking graphic how much the vessel is degraded and how much more fuel he needs to push the vessel through the water. That power demand will display in absolute and percentage terms,” Büssow said. “Now he sees the performance is being degraded by 20 percent, so does it make sense to clean (the hull) at the next port? Should he use the high-performance coating?” 

The DNV GL system strives for a standard that is “with the ISO and a little bit more,” Büssow said.

“We do more corrections in our investigation process, so we can be a little more accurate,” he said. “We correct for draft and trim, for instance.”

The Hempel-DNV GL announcement in December said ECO Insight “is able to benchmark a vessel’s performance relative to other similar vessels. … By tapping into additional ship-specific data (beyond what is used to calculate performance) ECO Insight’s analytics can be used to further customize paint specifications upfront and to proactively manage performance once the ship enters service.”

The analysts believe all the monitoring ultimately will help the coatings manufacturers — in particular, Hempel and Jotun in the DNV GL project — learn more about the properties of their own formulations. The companies can compare various active ingredients and have a much better idea if biocides may be releasing too quickly or too slowly.

“Both of them are interested in improving their product as a long-term goal,” Büssow said.

By Professional Mariner Staff