Time for launch – have you checked out your antifouling paint?

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As spring approaches, Sweden’s marinas are a hive of activity. Scraping, sanding, washing and painting are being carried out wherever you look. As a boat owner, what do you need to consider when choosing your antifouling paint?

“You should select an antifouling paint that contains the minimum amount of biocides necessary, and you should use it sparingly. The lower the salinity of the water, the less biocides are needed. Ideally, however, you should try to avoid biocides altogether,” says Melissa Feldtmann, researcher at IVL Swedish Environmental Research Institute.

The aim of biocides is to kill or impede aquatic animals and plants – especially barnacles and algae – that attempt to grow on the bottom of boats. Various forms of copper-based biocides are currently used, although the trend is moving towards opting increasingly for biocide-free methods.

ANTIFOULING PAINT IS DISPERSED THROUGHOUT THE YEAR In the past, coal tar and lead oxide were used. PCBs were added to antifouling paint during the 1960s, and in the early 1970s paint manufacturers began adding tributyltin (TBT). Although these substances have long since been banned, they are still affecting the environment. A standard 30-foot sailboat from the 1980s, with multiple layers of paint, can be covered in several kilograms of paint containing several percent of copper, zinc, TBT and other biocides.

The substances from the antifouling paint are dispersed throughout the year: in the spring when old paint is being scraped away during painting, in the summer when the boat is in the water and in the autumn when you are washing and repairing the hull ahead of the following season.

The Baltic, for example, acquires an estimated 57 tonnes of copper from antifouling paint from recreational boats each year, according to estimates from 2018.

HOW SERIOUS IS THE POLLUTION IN MARINAS?

“Measurements in normal marinas show that the levels of copper, zinc and TBT are often so high that the soil at ground level around the mooring sites can be classed as hazardous waste. Around older yacht clubs and shipyards, the levels of TBT, PAH, lead, PCBs and mercury are often so high that adults, children and pets should not be spending time there,” says Melissa Feldtmann.

A mixture of old and new hazardous substances is also found on the seabed adjacent to loading and mooring sites. These are stirred up by propeller movements, waves and currents and then spread to nearby areas. Climate change also entails an increased risk of the spread of pollutants in association with flooding and torrential rain.

RECREATIONAL BOATS OFTEN MOORED IN SENSITIVE BAYS The extent to which biocides harm the marine ecosystem is largely dependent on the chemical composition of the sea, as well as on where the pollutants end up.

“Most of the recreational boats in Sweden are moored in sensitive bays that are important nurseries for many fish species. In addition, newly painted boats are launched at the time of year when biological life in the water is at its most active, and this has an adverse effect on the shallow ecosystems,” said Anna-Lisa Wrange, researcher at IVL.

Melissa Feldtmann, researcher at IVL Swedish Environmental Research Institute

WHAT RESPONSIBILITY DO THE HARBOURS HAVE? “The responsibility for choosing the right product, method and form of protection is the responsibility of each and everyone. However, once damage has occurred and no specific boat-owner can be singled out, the responsibility rests with the principal that is deemed to be in control of the operation. After this, the principal may share the costs for rectifying the damage. Marinas that opt against the use of antifouling paints containing biocides and replace them with other methods are making a significant contribution. There are several good examples of harbours that are leading the way and demonstrating that it is possible,” says Melissa Feldtmann.

Advice for boat-owners

• Of course, you only use antifouling paint that is approved for the water in which the boat is located. Information about approved paints for your home port can be found on the

Swedish Chemicals Agency’s website.

• No paints containing biocides are permitted in fresh water or along the Norrland coast (down to Örsker).

• In most Swedish harbours, you only need to paint the hull every two or every three years and only touch up the most exposed areas as necessary.

• If the boat’s home port is in the Baltic Sea, where the barna cles only reproduce once or twice per summerseason, you can opt to refrain from painting the hull. Instead, you can sign up to the barnacle warningtext service via www.batmiljo.se and scrub the hull while the barnacles are still small and easy to remove.

• If you are planning to go on a longer trip, you may need to adapt your choice of paint and painting method over the sea son. If you are heading towards sea with a higher salinity, you should wait until the last moment to apply the west coast paint. • Barnacles will not survive in freshwater. Mooring your boat in freshwater for a couple of days is an environmentally friendly way of preventing barnacles from growing.

• Don’t forget that if you buy a second-hand boat, you may need to remove the old paint before you launch it in your home harbour.

• Don’t launch the boat too early unless you’re planning to use it straight away, or store the boat on land when it’s not in use. By shortening the time that the boat is in the water, you can reduce the need for both antifouling paint and maintenance.