Finding the Right Hull Coating

Boat antifouling works by releasing biocides at a controlled rate from the paint film, preventing barnacles, weeds, slime, and other marine growth from attaching to the hull. Left untreated, a fouled hull creates significant drag that can eat into speed and push fuel consumption up. That's on top of the eventual cost of having the boat hauled out and scrubbed back to bare gelcoat.

Consider the following when choosing a coating:

• Hull material: fibreglass, aluminium, steel, and timber all have different compatibility requirements
• How often the boat moves: a moored cruiser that sits for weeks needs different protection than a launch used every weekend
• Where it's berthed: warmer northern waters foul faster than cooler southern ones, and harbours with high biological activity will challenge any coating

A well-matched antifouling can give you 12-24 months between recoats before the hull needs attention again.

Antifouling Paint for Different Boat Types

Soft antifouling

Soft antifouling is a partially water-soluble coating that wears away as water moves across the hull. It splits into two main types.

Standard ablatives erode unevenly, wearing faster where water flow past the hull is greatest. This makes them a good pick for boats that spend time out of the water (they hold up well between seasons), but less suited to high-speed craft used frequently, where the film can wear through too quickly.

Self-polishing ablatives erode evenly, leaving a smooth surface that reduces drag and improves fuel economy. They're the better call for regularly used boats where a consistent finish and performance are key.

Hard antifouling

Hard antifouling bottom paint is best suited to high-speed boats, racing yachts, and trailer boats that get scrubbed between trips, since the harder surface stands up to repeated cleaning. Unlike ablatives, hard antifouls work through contact leaching, releasing biocides directly into the water without the coating wearing away, which is why they also handle long periods out of the water without losing effectiveness.

Propeller antifouling

Props, shafts, and other underwater metals foul fast and lose efficiency. The moment they do, a barnacled propeller can shave a couple of knots off your cruise speed. Foul-release coatings create a slick surface that growth struggles to bond to, with the bonus that any growth that does attach comes off easily under load.

Transducer coatings

Transducer coating protects the working surfaces of depth sounders and fish finders without interfering with sonar performance. Standard antifouling boat paint would block the signal, so use a purpose-made transducer coating instead.

Applying and Maintaining Antifouling Paint

Old antifouling needs to be scraped or sanded back to a sound base, and new hulls need an appropriate primer first. Compatibility varies between products, so check the manufacturer's instructions before you commit, as mixing incompatible coatings will ruin an otherwise good job.

Before you get started, know that antifouling biocides are toxic by design. Wear gloves, eye protection, and a respirator (not a dust mask) whenever you're disturbing old coating or applying new. Set up a controlled work area with good ventilation, contain your waste as you go, and dispose of leftovers through proper channels rather than washing them down the marina drain.

Plan for a fresh coat every 12-24 months depending on the product, usage, and water conditions. Warm northern waters generally need annual repainting; cooler southern berths can often stretch to two years.

Read our complete guide to antifouling for more information.

Shop Marine Paint and Hull Protection at Burnsco

Burnsco's marine antifouling paint range covers everything from antifouling to topcoats, with the prep gear and accessories you need for the job. Order online for 1-hour click & collect at any of our 19 stores nationwide, or pop in for a chat. Browse our top coat, varnish & teak oil, primers & undercoats, and sealants & adhesives to complete your maintenance kit.

Frequently Asked Questions

How long does antifouling paint last on a boat?

Many quality antifouls are designed to deliver 12-24 months of protection, depending on the product, location, and usage. Boats in warmer northern waters generally need annual recoating; cooler southern berths can often stretch to 18-24 months.

Can I apply antifouling paint over existing antifouling coatings?

Often yes, but check compatibility first. Most antifouls can go over the same type and brand, but mixing hard and soft coatings tends to cause adhesion problems, so check the manufacturer's compatibility chart or ask our team if you're not sure what's already on the hull. When you're ready to paint, make sure you scrape or sand back any loose or flaking coating.

What happens if I do not use antifouling paint?

A boat berthed full-time without antifouling will foul within weeks. Slime appears first, then weed, then hard growth like barnacles. The result is lost speed, higher fuel use, and eventual damage to gelcoat or timber.

Is antifouling paint suitable for both saltwater and freshwater boats?

Yes, though the formulation differs. Saltwater antifouls are tuned for higher biocide release rates; freshwater versions target lake algae and other freshwater species. Check the product label, since using the wrong type won't deliver the protection you're paying for.

Can antifouling paint be used on aluminium boats?

Yes, but you need to choose carefully. Standard copper-based antifouls cause galvanic corrosion on aluminium, so they must never be used on aluminium hulls, stern drives, or outboard legs. Look for products specifically labelled as aluminium-safe, which use alternative formulations designed for aluminium substrates. Altex's Sea~Barrier Alloy 100 PLUS is one example purpose-built for aluminium commercial and pleasure vessels.