Applying antifouling to boats, step by step

→ How do you apply antifouling to your boat?

For the maintenance of your boat, painting with an antifouling is essential and recommended every year before relaunching for the new season.

Applying antifouling to your boat is a key step in protecting the hull from marine soiling and prolonging its durability and performance on the water. Good preparation and the use of an antifouling roller guarantee effective protection.

Here's how to apply antifouling, step-by-step, for optimum results on your boat.

1: Protect yourself and prepare your environment

Antifouling involves the use of chemicals containing biocides. It is therefore essential to work in complete safety:

▪️ Work in a ventilated area.

▪️ Wear protective gear: nitrile or latex gloves, overalls, goggles, solvent mask.

▪️ Avoid skin contact and wash after handling.

Good to know: Biocide-free antifouling is a more environmentally-friendly alternative.

2: Inspecting and cleaning the hull

Before you begin, inspect the hull:

▪️ Check for cracks, blisters or poor adhesion of the old antifouling boat .

▪️ Scrape off seaweed and shells with a scraper.

▪️ Wash the hull with a high-pressure jet to remove residues and impurities.

Please note: How often should I antifoul my boat? The ideal frequency is once a year, applied between late winter and spring, especially if you sail in salt water.

→ How many coats of antifouling?

For optimum protection, we recommend applying at least 2 coats of antifouling, and up to three on the most exposed areas such as the keel, rudder and waterline. The number of coats also depends on the type of antifouling used: an erodible antifouling may require an extra coat, while a hard matrix antifouling offers greater resistance over time.

3: Sanding and degreasing

Antifouling in poor condition must be stripped before a new coat is applied. Good sanding helps the antifouling paint adhere better:

▪️ Lightly sand the surface with P120 abrasive to remove any remaining irregularities.

▪️ Clean again with fresh water and allow to dry completely.

Please note: Removing antifouling from boats is never easy. Each method has its advantages and disadvantages, and none stands out as the perfect solution. Removing antifouling takes time and preparation. The use of a sander for boat antifouling sanding can be useful when cleaning is difficult.

4: Masking unpainted areas

Before you start painting with antifouling, protect the unaffected areas:

▪️ Apply masking tape to the waterline to prevent spillage.

▪️ Protect propellers, anodes, sensors and underwater lights .

Tip: Remove the boat tape just after application, before the paint has fully hardened, to prevent flaking.

→ When to apply antifouling?

Ideally,antifouling should be applied before the start of the boating season, generally in spring, when temperatures are milder and allow for optimal drying. To ensure effective protection, it is important to respect the drying times indicated by the manufacturer before launching the boat.

5: Priming and repairing defects

Beforeapplying antifouling, it is important to prepare the surface:

▪️ Repair cracks with an epoxy coating .

▪️ Apply a primer for better adhesion:

Single-component primer: sufficient if the old antifouling is in good condition.

Two-component primer: recommended after osmosis treatment or if the old antifouling is peeling.

Good to know: An antifouling primer also helps prevent corrosion on metal substrates.

6: Antifouling application with a roller

Applying antifouling with an antifouling roller is the most effective method for even coverage.

▪️ Mix the antifouling gently to homogenize the biocides.

▪️ Use a special antifouling roller to avoid bubbles and ensure good adhesion.

▪️ Apply in criss-cross strokes, without stretching the paint too much, to optimize thickness.

▪️ Add a second coat on the most exposed areas (keel, rudder, waterline).

Tip: Due to its biocide-free composition, a ecological antifouling may require more regular application, but has less impact on the environment.

→ Which antifouling to choose?

It's essential to know which antifouling to choose before applying it to your boat, otherwise its performance will be reduced. Whether it's a hard matrix antifouling for fast boats or a biocide-free antifouling to reduce environmental impact, follow the manufacturer's instructions to optimize the product's adhesion and durability.

7: Drying and finishing

▪️ Respect the drying times indicated on the pot before putting back in the water.

▪️ Check the hull for overlooked areas.

▪️ Touch up any hard-to-reach areas.

▪️ Clean up any spills with an acetone-soaked cloth.

Good to know: If you use an eco-friendly antifouling, it may take longer to dry than conventional antifouling paint.

→ Painting an antifouling for a long-lasting boat fairing

Antifouling application is essential to protect your boat's hull from marine fouling and preserve its performance.

For optimum protection, it's important to paint the antifouling in compliance with each step: surface preparation, application in several coats and respecting the antifouling drying time. As a reminder, the average drying time for an antifouling depends on the type of product used, weather conditions (temperature, humidity) and the substrate, and can vary from 12H to 48H before the boat is put back in the water.

Finally, a suitable antifouling roller guarantees even coverage and better adhesion of the product, ensuring smoother sailing and a well-maintained hull. Use a 180 mm roll for large surfaces and a 110 mm roll for narrow areas.

Back to menu