Which antifouling is suitable for GRP boats?

GRP is compatible with many antifouling systems. The right choice therefore depends less on the material alone than on fouling pressure, speed, time afloat, use and the existing coating system.

Which system suits the use?

• Self-polishing: for many sailing and motor boats kept afloat during the season. Seajet 031 is intended for normal to medium fouling, Seajet 033 for heavy fouling.
• Hard antifouling: for fast boats, regular launching or drying moorings. Seajet 037 is approved up to 70 knots.
• Biocide-free: Seajet 021 EKO erodes, Seajet 2300 forms a hard surface for trailer boats, and Bioclean Eco is a silicone foul-release system.

The cruising area remains decisive because local fouling pressure can vary widely even within fresh or salt water.

Does GRP always need a primer?

No. Preparation according to the data sheet may be sufficient on a sound, compatible existing coating. Bare or repaired GRP requires a suitable primer system. Seajet 117 Epoxy Primer can be used as an adhesion primer and multi-coat barrier system.

Antifouling itself is not osmosis protection. A closed barrier requires several epoxy-primer coats at the specified dry-film thickness. Coat number and intervals depend on the data sheet and laminate condition.

Check the existing coating

Clean the hull and check that existing layers adhere firmly. Cracked, flaking or unknown systems must be removed or separated by an approved barrier coat. The compatibility table shows possible systems.

Calculate coat number and quantity

Many antifoulings require two coats for first application; individual products and multi-season systems differ. Theoretical coverage applies per coat, and tools, hull shape and substrate cause additional losses. The quantity calculator estimates underwater area, while the configurator accounts for product and coating system.