How do I safely remove antifouling paint from a boat?

The safest practical way to remove old antifouling is with a vacuum-connected scraper or a chemical stripper approved for your hull material, collecting all scrapings and wash water. Remove loose paint and excessive build-up down to sound, compatible primer; bare gelcoat need only be exposed if the coating system or hull repairs require it.

Check what needs removing

Inspect the clean, dry hull closely and try a small test patch. Flaking edges, deep cracks, powdery layers and exposed primer help show whether local preparation will suffice or a full strip is needed.

Sound antifouling need not come off every year. Self-polishing coatings commonly need a thorough strip after roughly 5 to 15 years, depending on application thickness and use. Hard antifouling needs regular abrasion to control build-up.

• Local flaking: remove all loose paint and feather the edges into firmly attached paint.
• Thick, widespread cracking: strip the accumulated antifouling back to a stable base.
• Changing paint systems: check the new manufacturer's compatibility guidance before choosing between stripping and a specified tie coat.
• Blisters or keel rust: investigate separately, as these may require removal beyond the antifouling.

Silicone foul-release coatings need their own removal and preparation procedure. Ordinary primer will not reliably adhere to silicone contamination.

Prepare the area and protection

Remove slime and fouling in the yard's designated washdown area, preferably immediately after lifting, before it dries hard. A tarpaulin catches solids but does not treat contaminated water. Collect wash water through the yard's approved arrangements.

Before scraping, spread heavy polythene or a tough tarpaulin beneath the entire working area. Turn up the edges and secure it against wind. Keep access routes clean so boots do not carry paint fragments around the yard.

For scraping or abrasion, wear disposable coveralls, gloves suitable for the product, eye protection and a properly fitted P3 particulate respirator. Chemical stripping may require additional respiratory protection, as specified by the product's safety data sheet.

Have the yard confirm that the boat is securely supported. Leave moving props or exposing covered patches to yard staff.

Use a suitable hazardous-dust extractor, normally dust class M or better where specified, rather than a domestic vacuum. Check that its filters, bags and hose connections suit the work.

Choose a removal method

Vacuum scraping is usually the best starting point for thick, brittle coatings. A 50 to 65 mm carbide scraper with extraction removes substantial layers without turning the entire coating into dust. Keep the blade almost flat and use light pressure. Round off sharp blade corners to reduce the risk of gouging, and practise on a small area first.