Maritime trade and transportation have thrived since the Industrial Revolution. Sea transportation impacts the environment, particularly through greenhouse gas emissions, which are always the main headline related to large vessels and the environment. Cargo, passenger, leisure, research, or fishing, ships are used these days for different purposes, but the issue of hull cleaning is hardly the main topic regarding shipping and the environment.
The hundreds of ships sailing through the ocean every day carry algae, barnacles, and mussels, alongside other organisms stuck on the hull. They are carried hundreds of miles from their native habitats to other ocean parts. This process is known as biofouling and it increases drag on ships, which in turn consumes more energy to power the vessel. This means burning more fossil fuels, and we all know that this contributes to global warming.
According to the Review of Maritime Transport 2023 by UNCTAD, maritime transportation is responsible for 3% of global greenhouse gas emissions and has increased by 20% over the last decade. “Scientists estimate that up to 60-70% of aquatic invasive species are spread through biofouling,” said Runa Skarbø, Bellona’s senior adviser on shipping.
Hull cleaning is environmentally necessary to reduce global warming. Doing it more sustainably ensures environmental sustainability. If you own a vessel, there are sustainable options to keep the hull clean, either through personal effort or sustainable hull cleaning services from companies.
Why Is It Important to Clean Your Hull?
Due to being constantly submerged in water, ship hulls become a temporary habitat for aquatic life. Biofouling is the build-up of algae, barnacles, and mussels, alongside other organisms on moist surfaces.
Biofouling contributes to global greenhouse gas emissions as it increases fuel costs, leading to up to 40% more energy consumption to power ships. It’s detrimental to the environment in more than one way.1 If regular cleaning and maintenance are not done, biofouling may cause serious problems on the vessel’s hull.
Ships’ hull and propeller fouling result in increased roughness on these moist surfaces. Biofouling is responsible for increased hydrodynamic hull resistance and reduces propeller efficiency. Due to the ship’s hull and propeller fouling, higher fuel consumption occurs, hence leading to the emission of greenhouse gasses.2
Generally, ships are designed to be hydrodynamic, to cover long distances across large bodies of water. Biofouling affects their travel speed by creating drag.
Hull cleaning solves the problem of biofouling. It’s a process of defouling, in simple terms, removing accumulated plants, algae, barnacles, mussels, and other organisms from the hull. Regular cleaning of your vessel’s hull eliminates biofouling drag.
Since your vessel’s bottom is always submerged in water, regular cleaning is not always part of the daily or weekly routine. However, regular cleaning of your vessel’s bottom should be considered as it increases the vessel’s performance, ensures sufficient travel time, and reduces fuel consumption, which saves you money spent on resources. It reduces the expenses of re-defouling, the amount of vibration in the turning gear, and most importantly, it prevents biofouling and the growth of invasive species.3
While it’s important to clean your hull, what is more important is doing it sustainably. Commonly used methods for preventing fouling may lead to significant environmental issues such as chemical pollution due to the antifoulants released from the hull’s coatings, and the risk of carrying non-indigenous species from fouled hulls.4
Hull cleaning can be performed in or out of water. But let’s remind you that your vessel’s bottom is not the only part that needs cleaning. The propellers, running gear, shafts and intakes also should be cleaned and properly maintained for better performance.
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Hull Cleaning: How Often Should You Do It
Cleaning and maintaining your vessel hull also provides the opportunity to access the underside of your ship to check if the parts submerged in water require urgent attention.
According to sources, most ship owners clean their vessel’s hull monthly or every two months. However, Thai Subsea Services recommends getting hulls cleaned every six months to maintain hull efficiency.
Waiting too long for your hull cleaned creates biofouling, which may lead to using more abrasive tools and products for defouling. The application of abrasive tools in hull cleaning can also lead to the removal of the hull’s paint or antifouling coating.
It’s best recommended to use less abrasive tools for cleaning while monitoring biofouling accumulation. Frequent scrubbing scrapes the hull surface off, reducing its ability to prevent fouling from accumulating on the underside.
This is why sustainable cleaning should be prioritized—not only for environmental reasons but to ensure anti-fouling coatings and hull paints last longer for better vessel performance.
What Is the Best Way to Clean the Hull of Your Vessel to Protect the Environment?
Eco-Friendly Chemical Cleaners and Gels
Eco-friendly chemical solutions are new types of cleaning products for cleaning your vessel’s underside without causing any environmental harm. They can be applied underwater by divers or robots to prevent biofouling. It involves coating the vessel’s bottom underwater with cleaning chemicals. Once applied to the underside, the chemicals are left on the surface for several hours before they are washed off with the fouling.
Depending on the chemical’s formulation and the level of fouling on the underside, application and reaction will vary, but expect it to last for a time frame of 8 to 24 hours.
Hull cleaning comes at a price, especially for this cleaning technique that uses eco-friendly chemical solutions. Expect to pay up to $3,000 and above for application services and the cost of chemicals.
Biological Cleaning Agents
This hull cleaning method relies on cultivating marine organisms to prevent fouling. It cultivates marine organisms like enzymes or certain bacteria with the natural ability to consume fouling organisms. It’s sustainably achieved without causing any damage to the hull or the marine environment.
The application of these biological cleaning agents to the hull is less abrasive and efficient for smooth surface cleaning. Application time lasts longer as the cleaning process can take anything from a few days to a week. Applying the cleaning agents requires a longer time to work effectively.
For the application cost, it ranges from $2,000 to $5,000 per treatment. It’s sustainable and worth it for defouling your vessel’s hull. Bio-cleaning agents are designed for effective cleaning, and they also reduce the need for frequent underside vessel cleaning.
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Hiring or Buying an Underwater Cleaning Bot
Robots technologically advanced and engineered for underwater tasks can prevent drag on your vessel caused by biofouling. Robots designed for underwater conditions function effectively for this. They are engineered to use rotary brushes or jets to remove plants, algae, barnacles, mussels, and other organisms stuck on the hull’s surface. These robots are operated remotely by attaching them to the underside.5
Using robots is a more technologically advanced technique for underwater tasks, but it comes at a steep price. According to sources, the upfront cost of getting a cleaning robot ranges from $50,000 to $200,000. Buying them is a good investment in the long run. They are cost-effective for regular hull cleaning.
On the other hand, if you prefer to hire a robot for this underwater task, prices range from $2,000 to $10,000 for one-time use. Price may vary depending on factors like locations and fouling conditions.
But how long can it take these cleaning robots to complete underwater tasks? Cleaning robots function at a rate of about 1,500 square feet per hour. So, vessel size determines the number of hours to clean a vessel’s underside. For an average-sized commercial shop, expect tasks to be completed between 10 to 20 hours.
Utilizing the Service of Local Diving Teams in Ports
Paying for the services of local diving teams is another option that is affordable and eco-friendly. These local diving teams can get the job done within 6 to 24 hours. They will use manual tools and small machinery to remove fouling from the ship’s undersides. Local diving teams that specialize in underwater tasks are usually found in ports around Southeast Asia or parts of Central America.
The price for their services can range from $1,000 to $5,000. For this price, you get a full cleaning service from a local diving team not using harmful chemicals.
Sustainable Hull Cleaning Services
ECOsubsea
ECOsubsea is a Norwegian-based company that offers sustainable hull cleaning services. According to ECOsubsea, they emerge as a beacon of sustainable innovation, ensuring full waste collection and swift service to clean vessels with patented technology.6
ECOsubsea Hull Cleaning offers top-quality biofouling removal. According to the company’s statement, they have been in the business of hull cleaning for “over a decade, working with ship owners, coating manufacturers, ports and environmental regulators to develop an award-winning solution for sustainable hull cleaning and biofouling collection”.
ECOsubsea operates in other European countries like the United Kingdom, France, the Netherlands, and Belgium, owning serviced ports in these countries. The Norwegian-based company as of when this article was written have captured 172,699 kilograms of biofouling.
It’s worth considering ECOsubsea hull cleaning services if your vessel sails close to the North Sea. Their sustainable hull cleaning services prevent the spread of non-indigenous invasive species in the ocean. ECOsusbsea claims that their services “capture biofouling and pollutants to ensure vessels sail into greener future with reduced carbon emission and enhanced performance”.
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GAC Panama’s Hull Cleaning Services
According to GAC Panama, they “provide a suite of shipping services to vessels calling at Panamanian ports or transiting the Panama Canal”. GAC Panama is all about sustainable hull cleaning services.7
They work with Remotely Operated Vehicles (ROVs) for large ships calling at Balboa and Cristóbal ports, GAC Panama says. Their hull cleaning solution is up for the underwater task of removing fouling, a cleaning technique that ensures reduced fuel consumption and CO2 output.
GAC Panama’s underwater cleaning services offer optimal performance and guarantee energy efficiency. The Panamanian-based company used advanced technology to perform underwater tasks. Their ROV uses adjustable seawater jets to eliminate fouling.
By using the ROV, GAC Panama minimizes the risk of scrubbing off expensive anti-fouling coatings. GAC Panama pumps all collected fouling into an onboard filter, which is deposited into containers. The collected fouling is later disposed of by an approved environmental waste company.
Conclusion
Hull cleaning is environmentally necessary to reduce global warming. Keeping the hull of your vessel clean and doing it more often is a sustainable way to protect the environment. Biofouling is a catalyst for maritime transportation contributing to global greenhouse gas emissions.
We listed eco-friendly hull cleaning options worth considering. Top companies also offer sustainable hull cleaning services; ECOsubsea and GAC Panama offer cleaning services using technologically advanced systems.
Sources
- Kotrikla, A. (2009). Environmental management aspects for TBT antifouling wastes from the shipyards. Journal of Environmental Management, 90, S77–S85. ↩︎
- Oliveira, D. R., & Granhag, L. (2020). Ship hull in-water cleaning and its effects on fouling-control coatings. Biofouling, 36(3), 332–350. ↩︎
- Valchev, I., Coraddu, A., Kalikatzarakis, M., Geertsma, R., & Oneto, L. (2022). Numerical methods for monitoring and evaluating the biofouling state and effects on vessels’ hull and propeller performance: A review. Ocean Engineering, 251, 110883. ↩︎
- Rensink, K. (2023, January 31). Why your hull needs regular cleaning. VLS Environmental Solutions. ↩︎
- Song, C., & Cui, W. (2020). Review of Underwater ship hull cleaning Technologies. Journal of Marine Science and Application/Journal of Marine Science and Application, 19(3), 415–429. ↩︎
- Sustainable Hull Cleaning — ecosubsea. (n.d.). Ecosubsea. ↩︎
- Safe, eco-friendly hull cleaning services for vessels calling at Balboa and Cristóbal ports. (2021, July 8). GAC Panama. ↩︎