How do you remove existing antifouling?
If you want to remove antifouling from your boat, there are a number of techniques you can choose from. Which one is right for your boat depends on the antifouling used and your personal preferences. Before starting, you should always mask off the waterline and cover the floor you are working on with plastic sheeting/tarpaulin to collect any antifouling residue. Follow the product instructions and wear PPE (e.g., face mask & goggles).
Removing antifouling with a
As part of the preparatory work for removing antifouling, old and loose pieces should be removed with a high-pressure cleaner and fresh water. It is best to do this straight after the boat has been brought ashore, and in a suitable place.
1. Sanding antifouling
Antifouling can be sanded off relatively easily. You'll need a sander and appropriate sandpaper. When sanding, try to keep the aerial distribution of dust particles to a minimum so that you do not in-hale them. AMake sure you wear personal protective equipment such as a face mask and goggles. It is recommended to use a sander that has a vacuum cleaner attachment, so that antifouling residues are collected in a way that is not harmful to the environment. Vacuum sanding is also popular way of removing antifouling residues.
Note: All known antifouling types can be sanded.
What is the right sandpaper for removing antifouling?
Different types of sandpaper are available for removing antifouling, and choosing the right one is im-portant. Coarse sandpaper doesn't tend to clog up as quickly as fine-grained sandpaper. When remov-ing self-polishing antifouling, be aware that it has a resin that becomes warm and soft more quickly when sanded than hard antifouling. Because of this, sandpaper can clog up more quickly, therefore, a 120 to 180 grit is recommended. Particular care should be taken with this method of antifouling removal, especially on curves on your boat, as you can very easily damage the gelcoat and laminate.
Sanding antifouling - procedure
Hook up your vacuum cleaner to the sander and make sure you are using the correct sandpaper. Sand off piece by piece, layer by layer, being careful to keep the sander flat to the surface. Try not to apply too much force as this could lead to cracks and scratches.
Sanding antifouling with an electric sander has the advantage that it is relatively quick. In addition, it roughens the surface, resulting in better adhesion. The drawback to this method of removing underwater paint is that, because antifouling is quite soft in its composi-tion, the sandpaper clogs very quickly. You'll need to change the sanding discs frequently, which can result in high costs.
2. Removing antifouling using a paint scraper
A paint scraper (wall scraper or putty knife) can be used to remove old antifouling. Ideally, you should choose one with a vacuum cleaner attachment, which will save you needing to labo-riously pick up the removed antifouling from the floor later and will also be better for your health. Wear additional nose and mouth protection, plus goggles, as removing antifouling is dusty work. Using a scraper requires some practice, be careful not to accidentally damage the gelcoat.
Note: You can use this method for all types of antifouling.
Using a scraper to remove antifouling - procedure
If you have a vacuum attachment, connect your scraper via the opening on the lower end. This way, whatever you remove will be collected in a container and you the floor won't get dirty. Grab the handle with one hand use your other hand to hold the head of the scraper firmly. Keeping the blade straight, apply a little pressure to scrape off the antifouling. You should be able to remove several layers. Note: Don't tilt the blade, otherwise you could scratch the gelcoat. Any remaining paint that does not come off can usually be sanded off afterwards.
Scraping antifouling has the advantage of being able to remove several layers of antifouling and primer quickly and consistently. Vacuum scraping is also much better for the environment. It is also cheaper than using a sander. The downside is that it can be physically demanding, so make sure you pace yourself and take plenty of breaks.
3. Chemical stripping antifouling
This method of removing antifouling involves loosening the layers of antifouling with a chemical strip-per, so that is then easier to remove afterwards.
Note: Even though this method is suitable for most antifouling, not all chemical strippers are suitable for the purpose. Apply to a small area of your boat first to see if it has an effect on your antifouling.
Note: Always check the instructions and wear appropriate PPE.
Tip: Only use paint stripper in fresh air or in well-ventilated areas!
Stripping antifouling - procedure
Stir the contents of the container well. Apply generously to a dry surface (boat hull) with a brush or roller. Proceed step by step, 1-2m² at a time.
Note: Never allow stripper to dry!
Cover the painted areas with plastic film to trap in the chemicals so that it can work better and not evaporate. The exposure time of paint stripper varies depending on the product, temperature and thickness of the old antifouling. After 10-15 minutes, test with a spatula or pallet-knife to see if the antifouling is loose enough to be removed. If the antifouling is soft and dissolved, remove or pull off with a (blunt) spatula. It should be a gel-like mass when it is ready to be removed. Depending on the thickness of the layer, you may have to repeat the process. After application, clean the hull thoroughly with water and a sponge. Sand off any residues. Make sure you dispose of the antifouling and stripper residues correctly.
Using a chemical stripper takes the grunt out of the work needed for scraping antifouling, but it is somewhat more expensive. A further disadvantage is that stripping won't completely remove the old coating. It's also not the most environmentally friend-ly way of removing antifouling and can be harmful to your health if care is not taken. It must also be disposed of properly.
4. Sandblasting antifouling
In addition to the three methods mentioned, another way to remove antifouling is sandblasting. Done by a professional, this method involves using water mixed with an abrasive granulate (sand) to blast layer after layer of antifoul from the boat with high pressure.
Note: Sandblasting is the most effective method of sanding, and is suitable for all surfaces and paint layers.
The advantage of sandblasting antifoul is that individual layers can be removed. However, you usually won't be able to do it yourself, and having it done by a professional could be very expensive.
Our video shows three methods of removing antifouling from your boat; scraping, stripping and sand-ing.
Removing antifouling - Summary
- Sanding antifouling: The fastest, but most expensive method. Work evenly and be careful not to damage the gelcoat.
- Scraping antifouling: Cheaper than sanding, but more physically demanding.
- Stripping antifouling: Takes the grunt out of scraping.
- Sandblasting antifouling: Usually requires an expensive specialist company.
- In the end, there are advantages and disadvantages to all methods for removing antifouling, and no one method can be recommended above all others. One thing is sure though, removing antifouling is hard, dirty work.
Comparison of the three methods
|Sanding antifouling||Scraping antifouling||Chemical stripping anti-fouling|
|Material||Canvas, Sander, Sandpaper, Vacuum cleaner||Canvas, Vacuum cleaner, Paint Scraper||Canvas, Film, Brush or roller, Palette-knife, Stripper|
Appropriate tools, equipment
Antifouling removal tips
To achieve the best possible results when removing antifouling, make sure you read and observe the warning labels of the antifouling removal product used and the antifouling
already on the boat.
1 Health and safety
Because antifouling contains harmful biocides, you should take appropriate measures to pro-tect yourself and others when removing it. Ensure good ventilation and wear protective equipment when working. Antifouling residues must be collected and disposed of properly. Be aware of local disposal regulations and act in accordance with environmental guidelines when removing antifouling.
2 What PPE (personal protective equipment) should I wear when removing antifouling?
When removing boat paint, your PPE should consist of safety goggles, protective gloves, a face mask with particle filter for sanding & protection against solvent vapours and protective clothing.