The AFS Convention is the International Maritime Organization's treaty on antifouling paint. It bans harmful organotins, tributyltin (TBT) above all, and sets up a way to control other harmful substances, which is how cybutryne was added. In the EU, Regulation (EC) No 782/2003 put the organotin rules into law for EU-flagged ships and ships calling at EU ports.
What it bans
IMO's summary is direct: all ships shall not apply or re-apply organotin compounds that act as biocides in antifouling systems. The convention covers ships flying a party's flag, ships operating under its authority, and all ships entering its ports, shipyards or offshore terminals.
The EU regulation says the same in two steps:
- Article 4: organotin compounds acting as biocides "shall not be applied or re-applied on ships".
- Article 5: ships may not bear them on their hulls or external surfaces, unless they bear a coating that forms a barrier to stop the old paint leaching.
Cybutryne
A later amendment to the convention controls cybutryne, a biocide used in some paints. IMO says ships must remove a cybutryne coating, or apply a coating over it, at the next scheduled renewal of the antifouling system, and no later than 60 months after it was last applied.
Certificates and declarations
Article 6 of the EU regulation sets the paperwork by size:
| Ship | Requirement |
|---|---|
| 400 gross tonnage and above | Surveyed and certified, before first entering service and when the antifouling system is changed |
| 24 m or more, under 400 GT | Carries an AFS declaration showing compliance |
| Under 24 m | No specific survey or declaration; member states may set their own measures |
The regulation's recitals explain the last row: boats under 24 m are mainly recreational craft and fishing vessels, already covered by EU rules on marketing antifouling products.
In the UK, Regulation 782/2003 was revoked and replaced by the Merchant Shipping (Anti-Fouling Systems) Regulations, SI 2024/509.
For surveyors
On most yachts under 24 m there's no AFS paperwork to see. What matters is what's on the hull: old hard paint built up in layers, flaking or blistering, and whether the yard's records show the product and when it went on. On a larger yacht, ask for the AFS declaration or certificate and check it against the yard's record of the last antifouling. See bottom paint for boats for paint types, and the out-of-water survey for the rest of the hull inspection.