Clean hulls with proven gains showcased at PortPIC

In-water cleaning is one of the fastest ways to cut fuel use, emissions and the spread of invasive species. At the seventh Port Inspection & Cleaning Conference (PortPIC), held in Mülheim, Germany, in  September, the message was clear: the industry must now prove what its cleaning systems and coatings deliver.

Jotun, co-founder and main sponsor of PortPIC, contributed two research papers. The first assessed the net climate benefit of proactive hull cleaning, weighing the footprint of the coating, robot and onboard station against the emissions they avoid. The second examined how controlled surface preparation and application can improve antifouling performance in sea chests, one of the hardest places on a ship to protect.

Why clean hulls matter

Shipping accounts for around 3% of global CO2 emissions, and fouling makes it worse. IMO's GloFouling study found that a slime layer just 0.5 mm thick, covering half the hull, can raise a ship's greenhouse gas emissions by 20 to 25%. Fouled hulls and niche areas also carry invasive species from one ecosystem to the next.

The commercial stakes are just as high. Fuel can make up as much as 60% of a ship's operating costs, and with the vote on IMO's Net-Zero Framework postponed in October 2025, owners face real uncertainty. Keeping hulls and niche areas clean is one of the most effective levers they have.

PortPIC 2026 brought together more than 60 participants, including port authorities, regulators, solution providers, research institutes and ship operators and charterers such as Shell, DS Norden, MPC Container Ships, Carnival Maritime and Spliethoff, to discuss in-water inspection and cleaning, standards, regulation and testing.

Volker Bertram, PortPIC co-founder and manager of VB Conferences, set out why the conversation matters now. "The IMO's biofouling convention is advancing and port state enforcement is evolving," he said. "PortPIC keeps participants informed and ahead, sharing best practice and talking openly about where the challenges lie."

Standards in place

ISO 6319, published in March 2026, gives in-water cleaning a common rulebook. Irene Tvedten of the Bellona Foundation, this year's Hull Management Hero award winner, explained that the standard favours no cleaning method. Instead, it sets out how a cleaning job is planned, approved, carried out and documented, giving owners and service providers one documentation package they can take from port to port.

So with standards in place, how do you verify the true effect of the cleaning? As keeping a hull clean cuts fuel use and emissions, a proactive cleaning solution surely has a footprint of its own. Once that is counted, how sustainable is it, really?

Anders W. B. Skilbred, Helle Vines Ertsås and Petter Korslund started from verified performance. Jotun Hull Skating Solutions combines a compatible antifouling coating with proactive robotic cleaning to keep the hull clean from day one. Third-party verification from DNV across 33 vessels, using in-water inspections, ISO 19030 speed-loss calculations and high-frequency and noon data, confirmed an always-clean hull with no measurable speed loss over an average of 3.5 years. For one large container ship, that meant a 17.7% cut in CO2 emissions, or around 17,300 tonnes a year.

Then came the other side of the ledger. The coating system, some 45,000 litres of primer, tie-coat and antifouling, accounts for around 407 tonnes of CO2. The onboard robot station adds about 14 tonnes and the cleaning robot just over one tonne, for a total of around 423 tonnes at installation. Power used in operation was left out as insignificant.

Over a simplified 25-year life, with the coating system renewed at each five-yearly dry-docking and the robot replaced every ten years, the footprint grows to around 2,036 tonnes. Against that stand estimated savings of 432,500 tonnes. The avoided emissions outweigh the footprint by more than 200 to one: the installation footprint is offset in under ten days of operation, and the full 25-year footprint in about six weeks.

"Everything comes with a footprint," Skilbred said. The paper acknowledges that the calculation relies on assumptions and some generic data but finds these do not change the overall picture.

The work also makes a wider point about transparency. With EU reporting rules such as CSRD and ESRS, and documentation such as Environmental Product Declarations, the tools to compare solutions on a like-for-like basis already exist. "What you want to improve, you need to measure," as Skilbred put it. For owners weighing proactive cleaning, the conclusion is clear: the climate case for a clean hull holds, even after the full footprint is counted.

Protecting the hardest-to-reach places

Jotun's second paper, by Tanja Perander and Henning Johnsen, turned to sea chests. These semi-enclosed seawater intakes are critical to a ship's operation, but their grates, corners, pipes and variable flow make good coating application difficult and diver access risky. They can harbour non-indigenous species even when the rest of the hull is clean, and regulators are paying growing attention to niche areas and how they are documented.

The question was simple: can controlled surface preparation and application reduce fouling in operational sea chests? Jotun ran in-service trials on six trading vessels with the owners' cooperation, documenting results through underwater photos and video alongside operational data such as speed, activity and sea temperature. On two of the ships, one sea chest was prepared and coated under controlled conditions and the other to normal yard practice, using the same antifouling product.

After up to three years in service, the difference was clear. Sea chests prepared to best practice showed only light fouling, while those prepared normally had barnacles, fouling on the gratings and inside the chest, and coating detachment. The ships traded largely in warm waters averaging around 25°C, and the authors found that favourable operating conditions alone could not explain the low fouling.

"Our key findings show surface preparation, adhesion, application quality and inspections are all critical to sea-chest antifouling performance," said Perander. The paper recommends assessing sea chests separately from the hull, since a clean grating is no proof of a clean interior. Ranking individual products will need further inspections, but the study gives a strong indication that controlled preparation and application of a suitable coating can reduce fouling in operational sea chests.

Robots, vision AI and cleaning on the move

Robotics and AI featured throughout the programme. Michael Stein of Vesselity showed how micro-ROVs and computer vision support condition-based hull management, replacing the single snapshot at dry-dock with frequent, repeatable inspections.

In-transit cleaning also drew attention. Levi Gershon of CRABI Robotics presented autonomous robots that groom the hull every 10 to 14 days while the ship is under way, arguing that only time at sea can support that frequency.

The closing forum, moderated by Bertram and Jotun’s Petter Korslund, brought together Karl Lander (Subsea Global Solutions), Mario Auran (Port of Bergen) and Thiago Pessoa (DS Norden). "I'll call it as a diving company: the robots are coming," said Lander.

The biggest hurdle may be awareness. "Everything we talk about needs to be translated into money, into the P&L of the commercial teams," said Pessoa. Lander added that hull cleaning is often booked as maintenance rather than decarbonisation, so the budget holder never sees the fuel savings. Auran noted that Bergen makes capture mandatory, "but that doesn't help if the ship can just go to the next port."

Speed came up too. One delegate warned that below about 14 knots fouling starts to settle, a reminder of why verified speed-loss data matters as ships slow down. For Bertram, the answer lies in transparency: if charter parties showed a ship's actual condition and predicted fuel consumption, charterers could choose the better ship, giving owners a reason to invest in the hull. Korslund noted that larger charterers are already approaching coating suppliers directly.

Summing up, Korslund said: "As the IMO convention takes shape, owners and operators need solutions they can be trusted and data to back them up. As co-founder of PortPIC, Jotun values the openness and collaborative spirit of this community. By sharing our research and real vessel data, we aim to help turn policy into practice and keep making progress towards clean, sustainable shipping."

The PortPIC 2026 proceedings, including both Jotun papers, are free to download at data.hullpic.info/PortPIC2026_Mulheim.pdf.