Prevent fouling without the use of biocides with foul release coatings
Biofouling is a serious issue that has afflicted vessels for as long as humanity has taken to the sea. The ancient Greeks are known to have used tar, wax and even lead sheathing to protect their ship bottoms, and, starting in the 1700s, the Royal Navy used copper sheathing to protect their ships from shipworm during their long months at sea. Though the biocidal properties of copper are still relied upon in the commercial shipping industry, the use of biocides is losing its appeal, and there are attempts around the world to ban these substances. With the tide turning, the industry is looking to non-toxic alternatives like foul release coatings.
Foul release coatings work by prevention rather than poisoning. They prevent the organisms that make up biofouling adhering to a vessel’s hull in a variety of ways. In this article we look at the foul release coatings on the market today, and some of the top products available in the UK.
The slippery coating technology behind foul release
Without biocides to rely on, foul release coatings need an alternative method to combat biofouling. Fouling release coatings are extremely low friction coatings usually based on silicone or fluoropolymers. The coating is incredibly smooth, and this combination of low friction and low surface energy is the physical mechanism behind its fouling release. Aside from preventing biofouling, the properties that distinguish foul release coatings include:
- Self-sustaining biofouling protection – The super slippery surface of the coating works to prevent biofouling adherence, but also works with the friction caused by the passage of the vessel through the water to brush away any slime or biofouling that does build up. Manufacturers are constantly improving their coatings so a slower rate of movement will cause this.
- Low friction – By creating an extremely low friction surface, these coatings not only ward off the adhesion of organisms they also reduce the drag of the vessel itself by allowing it to cut more easily through the water.
- Nontoxic – With no reliance upon biocides, fouling release coatings do not leach toxins into the water and so are not subject to the stringent regulations being placed upon their antifouling relatives.
- Fuel efficient – The combination of a low friction coating with foul release is reduced drag. When you reduce the drag of a vessel you also reduce the amount of fuel required to run it. Foul release coatings therefore also contribute to the fuel efficiency of a vessel and to significant fuel savings.
- Reduced CO2 emissions – With less power required to fuel expenditure and less regular coating applications comes reduced CO2 emissions.
The drive for industry innovation with fouling release coatings
Concerns are being raised internationally about the environmental impact of the enormous amount of biocides leaching into the seas from recreational, commercial, and cargo vessels. Copper has become the relied-upon biocide of the industry since the banning of TBT, though co-biocides like Econea and Irgarol 1051 are also extensively used. Washington State and California are leading the way in the US with copper regulation for pleasurecraft, and there have been attempts in a number of regions to curb its use.
The trend towards sustainability has meant that coating manufacturers are dedicating themselves to producing biocide-free alternatives like foul release coatings. These coatings use a physical rather than chemical deterrent to biofouling, and do not rely on the release of toxins into the environment. By highlighting the importance of environmental care, these products signal a change in the industry towards a more environmentally conscious future.
A case study for commercial fouling release systems: Intersleek 1100SR
AkzoNobel’s Intersleek 1100SR is the shipping industry’s first patented biocide-free, fluoropolymer-based fouling release system designed specifically to deal with the problem of slime. Biofouling can be divided into ‘macro’ and ‘micro’ fouling. Macrofouling includes barnacles and larger organisms, while microfouling is biofilm (slime) and bacterial adhesion. Slime, just like macrofouling, causes drag and so increases fuel consumption. Intersleek 1100SR improves static resistance to slime even in warm waters, and slime build up is released by the ship’s movement through the water, even with slow steaming.
With its slime release coating properties, Intersleek 1100SR has been adopted as the fouling release system of choice by a range of shipping companies. Grimaldi Lines use Intersleek on eight of their ferry vessels, while TUI cruises uses Intersleek on their new cruise ships, built by Meyer Turku. Outside the world of commercial shipping, AkzoNobel has partnered with The Ocean Cleanup to use Intersleek products on their devices and equipment. The Ocean Cleanup aim to clear plastic from our oceans, and their first project is to remove half of the Great Pacific Garbage Patch in the next five years.
A look at the top foul release coatings in the UK
The top foul release coatings for commercial vessels come from the top marine coatings manufacturers. AkzoNobel (International), PPG, Hempel, and Jotun all produce foul release coatings for the global marine fleet. Below we have outlined the top fouling release products from each company, and the benefits of each.
If you need foul release coatings for your shipping business or company, get in touch! Our experts are here to help. We collaborate with our coating partners to find the right coating solution for your needs. Our quotation service is free and as easy as just clicking the “Request a Quote” button beneath this article and telling us about your requirements.
|Foul Release Coating Product||Coating type||Description||Special Features|
|Hempel Hempasil X3+||Silicone hydrogel based||Biocide-free, two component, high solids content, fouling release coating for vessels with service speeds above 8 knots. Can also be used on propellers.||Creates a smooth surface with low surface energy that provides self-cleaning properties. This translates to high fuel saving potential.|
|International Intersleek 1100SR||Fluoropolymer based||Biocide-free, high volume solids, lower VOC foul release coating for newbuilding and maintenance and repair. Has a minimum service time of 5 years.||Excellent protection against macro and microfouling with its slime release technology. Slime is released by ship movement at considerably lower speeds than earlier generation foul release.|
|Jotun SeaLion Resilient||Epoxy-polysiloxane based||Biocide-free, high volume solids, underwater cleaning compatible coating for newbuilding and dry-docking application.||Designed specifically for excellent mechanical resistance and efficient docking. Resilient to mechanical damage in only 2 coats.|
|PPG Sigmaglide 1290||Silicone based||Biocide-free, 100% pure silicone binder, foul release coating for low slime pickup and easy slime release. For use at newbuilding, refurbishment, and maintenance.||Provides a dynamic surface with regeneration properties that allows a service time of up to 90+ months.Foul release is effective in static conditions.|