Antifouling Together with Respect for the Environment

The wind is gently picking up past 8 knots, the spinnaker is nicely filled, and the trimaran is accelerating. I take the helm to check that everything is OK: not a single vibration, the multihull is effortlessly gliding through the water. Pure bliss!
Sailing with a clean hull and appendages is not just a matter of maintenance or about fuel consumption, it also guarantees that you can enjoy the sensation of sailing to the full. My reverie is interrupted by the phone ringing - WhatsApp, to be precise. Thanks to Starlink, you can’t get any peace anywhere, even halfway across the Bay of Biscay! But it’s Emmanuel, the editor of Multihulls World... “Hi Brieuc, how’s the delivery going? Listen, I’ve got a favor to ask you...” Basically, after five minutes of discussion, I’ve been given the thorny subject of antifouling for the magazine’s next Forever Green special edition... and I know it’s not going to be an easy task! Let’s start with a quick overview of the various laws that apply before getting to the heart of the matter.

Between Protected and Prohibited

The purpose of antifouling paint is not only to slow down the formation of fouling on a vessel’s hull, but also to limit the spread of invasive species via the hulls of passing boats, a major issue in Europe, particularly in marine protected areas, or in relatively unspoiled areas such as Australia and New Zealand.

The first major measure to regulate antifouling paint appeared in 1998 at the instigation of the International Maritime Organization, a United Nations agency responsible for regulating the safety, security, and environmental performance of international shipping. The IMO is behind the International Convention on the Control of Harmful Anti- Fouling Systems on Ships (AFS). Adopted in 2001 and entered into force in 2008, it bans the use of coatings and paints containing tributyltin (TBT), an extremely toxic and persistent organic pollutant.

In Europe, the framework has been further strengthened, as TBT was banned in 2003 and the Biocidal Products Directive introduced initial regulations for ship repair areas. Only a dozen active substances, mainly copper- or zinc-based, are authorized, following an impact assessment. Since 2018, manufacturers have been subject to marketing authorization and advertising is regulated: the terms “organic (or “bio”),” “safe,” and “non-toxic” are prohibited.
In the United States, measures are targeted and progressive, similar to those in Europe, with a federal ban on TBT since January 2003. Some states have strengthened federal legislation with plans to ban copper in the medium to long term and with strict controls on leachates from haulout areas in boatyards.

In short, the elimination of TBT in the early 2000s forced manufacturers to reformulate their paints and work on improving the “discharge” of the biocide over time. We’re all familiar with conversations in yacht club bars about bottom paints “that don’t work nearly as well as they used to…” As ...