The earliest attempts at antifouling
Ships have played a huge part in shaping the history of our modern world, being involved in trading, exploration and migration and warfare as far back into the history books as you can go. The problem of marine biofouling is not a recent one and the history of the problem of antifouling dates back to ancient times when humans first began to explore the seas, although there is little information known about this.
The first mention of any kind of marine fouling was the Remora. The Remora is a fish also known in fable as the ‘ship-stopper’, it was supposedly able to slow down or even completely stop ships travelling at full speed. It was even mentioned by Aristotle around 4th Century B.C. Another Ancient Greek philosopher, Plutarch, later pointed out that this may be due to fouling on the boat hull rather than the remora being responsible for slowing down ships. He commented on how it was commonplace to have to scrape down the ship’s sides of weeds and filth to make it travel more easily through the water.
The earliest written records regarding the treatment of ship bottoms have been found which reference the 5th Century B.C. These earliest known methods of antifouling involved using natural substances, such as tar, wax, or oil, to coat the hulls of ships and boats. These substances may have been used to create a smooth surface that prevented marine organisms from attaching to the hull, however, they may simply have been used to make the hull watertight.
Later, in the 1500’s the Dutch physician Laevinus Lemnius wrote about using wire brushes and iron to brush and scrape away little shell fish from the underside of boats. Furthermore he eluded to the use of tallow, a product made from animal fat, could help the boat move through the water. Columbus’s ships may have also been covered with a mixture of pitch and tallow in order to help prevent them from being slowed by marine fouling. Other historians have reported the use of coatings of arsenic and sulphur being used to deter ‘ship worms’.
Other ancient forms of antifouling may have included the use of lead sheathing, secured by copper nails by the Greeks and Romans as lead cladded timber has been discovered from a Phoenician ship galley from around 700 B.C. The use of lead sheathing as a hull cover became widespread after Leonardo Da Vinci designed a rolling mill for producing thin sheets of lead. There were significant reports later on about the corrosive effect of lead on iron and lead was abandoned for use by the admiralty.
Copper and the birth of modern antifouling
The first significant innovation in antifouling towards what we use today came in the early 18th century when it was discovered that copper had antifouling properties. Initially, copper sheets were attached to the hull, but later copper paint was developed, which was easier to apply and more effective.
In 1708, British naval surgeon Dr. James Lind conducted an experiment in which he coated one side of a ship’s hull with a mixture of copper and arsenic, while leaving the other side untreated. He found that the copper-coated side had significantly less fouling than the untreated side.
The birth of antifouling paints
The first antifouling paints were developed in the 1800’s and contained a copper, mercury and arsenic as antifouling biocides mixed with solvents and binders that included turpentine, naphtha, benzine, shellac varnish, resin and tar. The use of copper in antifouling paints became widespread in the following decades.
A huge problem came when iron hulled ships were introduced, the copper antifouling paint particles reacted with and corroded the iron of the hull. There was, once again, a renewed interest in finding alternatives to copper paints that could be used on these ships.
The rise of toxic antifouling
In the mid-20th century, the use of highly toxic chemicals in antifouling paints became commonplace. Compounds such as tributyltin (TBT) were found to be highly effective at preventing fouling and, although it was first used in combination with copper antifouling paints, companies saw that it was just as effective on its own. It was safe for use on iron ships and was developed into two types of anti fouling paints; insoluble and soluble matrix paints, much akin to the hard and ablative antifouling paints on the market today,
However TBT antifouling paint is also extremely toxic to marine life. TBT was eventually banned in many countries, including the UK in 1987, due to its harmful effects on marine environment. Just this year another biocide, Cybutryne, was banned from use as an antifouling compound.
A Copper-based comeback story
After the ban of TBT, a large proportion of the boating industry went back to using copper based antifouling coatings although the industry was forced to work hard to create additional biocide additives able to target some copper-resistant species.
The limitations of traditional antifouling
While copper-based and toxic antifouling methods have been effective in reducing fouling, they are not without their limitations. For one, antifouling paints affect marine life, which is increasingly becoming a concern for environmental regulators, where the biocides and additives interfere with marine organism respiration, nutrient absorption and sensing as well as being able to build up in the food chain.
Additionally, copper-based antifouling requires regular maintenance and reapplication, which can be expensive and time-consuming. Therefore, in the past few decades, new antifouling technology has been introduced with a much reduced toll on aquatic systems.
The emergence of ultrasonic antifouling
In recent years, a new technology has emerged that promises to revolutionise the field of antifouling: ultrasonic antifouling. This technology involves the use of high-frequency sound waves to prevent fouling on the hull of ships and boats.
Here at EFC our ultrasonic antifouling systems work by emitting high-frequency ultrasonic waves into the water, which create vibrations that prevent the attachment of marine organisms to the hull, preventing further marine growth. The sound waves do not harm marine life and do not require any toxic biocides such as copper to be effective.
We have a range of ultrasonic antifouling kits for a variety of boat sizes and types, you can read more about how ultrasonic antifouling works on our blog or contact our dedicated team to discuss which ultrasonic antifouling system is right for you and your boat.
