Applying antifouling? Read all about antifouling!

What types of antifouling are there? And how do you apply the right antifouling to your boat? In this information article you will find everything about antifouling. Would you like more information, advice or tips about boat maintenance? Feel free to contact one of our specialists or check out our other information articles about refurbishing your boat.

1. What is antifouling?

Antifouling is designed to prevent the attachment and growth of marine organisms under your boat. When your boat is in the water it is exposed to small organisms, algae and mussels. This can have unpleasant consequences for the sailing characteristics of your boat. Speed ​​and controllability may decrease and fuel consumption may increase. Antifouling prevents small organisms from adhering to the underwater hull and keeps your sailing characteristics optimal.

2. What types of antifouling are there?

There are roughly two different types of antifouling: self-sharpening and hard antifouling systems. Polyestershoppen is a premium dealer of International antifouling and also supplies a wide range of antifouling systems from Hempel and Epifanes

Self-sharpening antifouling

Self-sharpening antifouling is also known as 'soft antifouling'. This antifouling 'wears out' itself through the friction of water, releasing biocides. The advantage of self-sharpening antifouling is that it does not build up layer thickness and can be applied over self-sharpening, as well as hard antifouling. However, it is necessary to apply a new coat every season.

Examples of self-sharpening antifouling:

  • International Micron LZ antifouling
    This self-sharpening antifouling is suitable for slow speed sail and power boats in fresh, brackish and salt water. The antifouling can be applied to all surfaces and is available in 4 bright colours.

  • International Cruiser One antifouling 
    International Cruiser One is a self-sharpening antifouling that is suitable for use in fresh and brackish water areas. Cruiser One contains copper and is suitable for sail and power boats (up to 25 knots).

  • Hempel Classic antifouling
    Hempel Classic is Hempel's best-selling antifouling. This efficient self-sharpening antifouling is suitable for slow speed sail motor boats. Hempel Classic offers excellent protection in all seasons and is suitable for GRP, wood and steel boats. The antifouling is not suitable for aluminum or other light alloy metals.

  • Hempel Mille NCT antifouling
    Hempel Mille NCT is a high performance self-sharpening antifouling. Mille NCT antifouling offers, through Hempel's patented binder technology, excellent protection in every season. The antifouling is suitable for boats made of polyester, wood and steel, but not for aluminum boats. Mille NCT antifouling is also known for its high colour retention. 

  • Hempel Ecopower Cruise antifouling
    Hempel Ecopower Cruise Antifouling is the ideal antifouling for slow speed sail boats in an environment with high environmental requirements. The self-sharpening antifouling is free of copper and biocide. Ecopower Cruise is suitable for almost all slow speed sail boats with a surface of polyester, aluminum, wood and steel!

Hard antifouling 

When hard antifouling comes into contact with water, substances dissolve in the paint that prevent fouling. The hard layer of paint remains and will not work after some time. So over the years you build up a hard layer of paint, which must be removed after a few years before you apply a new layer. You can therefore use this antifouling for several years and wet it in between to polish.

Examples of antifouling:

  • International Interspeed Extra antifouling
    International Interspeed Extra keeps the underwater hull of your boat free of fouling and algae for a year. International's hard antifouling is suitable for use in fresh, brackish and salt water, and is suitable for sail and power boats of all surfaces.

  • Hempel Hard Racing Xtra antifouling
    Hempel Racing Xtra hard antifouling is a high performance antifouling for high speed sail boats. The antifouling has a good price-quality ratio and provides excellent protection against fouling for high speed power boats and sail boats. Hempel Hard Racing Xtra is suitable for most boats and adheres well to GRP, wood and steel. Please note that this antifouling is not suitable for boats made of aluminum or other light alloy metals.

  • Hempel Ecopower Racing antifouling
    Hempel Ecopower Racing antifouling is a hard antifouling that is free of copper and biocide. This makes the hard antifouling very suitable for high speed sail boats in an environment where high environmental requirements are set. Hempel Ecopower adheres well to polyester, aluminium, wood and steel substrates. This makes the antifouling suitable for almost every high speed sail boat!

  • Epifanes Copper-Cruise 
    This copper and biocide containing high performance antifouling has a hard scrubbable surface and has an optimal copper release which functions well as an anti-fouling layer. The hard and scrubbable surface makes the Epifanes Copper-Cruise suitable for all types of vessels sailing up to 30 knots in fresh, brackish and/or salt water.

3. Which antifouling is permitted in the Netherlands?

In the Netherlands, antifoulant paint has to be authorised by the College Toelating Gewasbeschermingsmiddelen en Biociden (CTGB). If you use an antifouling that is not permitted, you risk a fine of 2,500 euros and you must remove the antifouling completely from the underwater ship. All antifouling systems for sale at Polyestershoppen are authorised by CTGB.

Hempel also supplies antifouling systems that are free of copper and biocide: Ecopower RacingEcopower Cruise and Hempaspeed TF (new).TF (new). Choose these environmentally conscious options if you will be sailing in an environment with high environmental requirements.

4. Which antifouling should I use?

The antifouling you need for your boat depends on the waterway and the speed and material of your boat.

  • Self-sharpening antifouling: low speed vessels (up to 25 knots). 
  • Hard antifouling: high speed vessels (faster than 25 knots).

To start with, it is important to know what antifouling is currently applied to your boat's underwater hull. You can find this out very easily by rubbing the antifouling with a wet cloth. If the paint runs off on the cloth, self-sharpening (soft) antifouling has been applied to the underwater hull. If it does not rub off, you are dealing with a hard antifouling.

Now that you know what antifouling has been applied to your boat, you can decide which antifouling to use. For slow-moving vessels (up to 25 knots), we recommend using a self-sharpening antifouling. If you apply soft antifouling to fast vessels, the antifouling will wear out quickly due to the friction created by fast sailing. For vessels travelling faster than 25 knots, we recommend applying hard antifouling.

5. How should I apply antifouling?

Now that you know which antifouling you need and you have the right antifouling, you can apply it to the underwater hull. We explain step by step how to do this easily. In our informative blogs, you can also find blogs on applying hard antifouling and applying self-sharpening antifouling.

Now that you know which antifouling you need and have the right antifouling, you can apply it to the underwater hull. We explain step by step how to do this easily. In our informative blogs,

Step 1. Make sure the substrate is in good condition

Make sure that the surface of the underwater hull you are going to apply antifouling coating to is in good condition. Repair cracks and holes, treat any osmosis and make the hull completely smooth again. Finish all damages with epoxy. If the substrate is bare steel, first apply  ZF Primer or International Interprotect as a primer. Over bare polyester substrates, first apply a coat of International Gelshield 200 or International Primocon as primer.

Step 2. Apply the antifouling

Mark (imaginary) the underwater ship in different parts, such as port bow, port stern, keel, rudder, etc. and estimate the area of each part. Pour the required amount of antifouling into a mixing cup and stir the antifouling. Then pour this into a roller tray and apply the antifouling using brush and roller. By estimating the areas and measuring, keep an eye on whether you may be applying too much or too little antifouling. For correct coating thickness, apply 1 litre of antifouling for every 9 m2.

Step 3. Apply a second coat of antifouling to heavily loaded areas 

After some time, the antifouling is repaintable. This time depends on temperature and can be found in the processing instructions. Apply a second coat of antifouling to bow, keel, rudder and waterline. After this has dried well, the boat can be launched. You will also find information for these times in the processing instructions.

Step 4. Next 

You have completely antifouled your boat and you can enjoy it for another 2 to 3 seasons. You can now get started with refurbishing the above water part!

When working with antifouling, take care of your own health and always wear nitrile/latex gloves and a vapour mask.

6. When should I apply antifouling?

The best time to apply antifouling is early spring, the start of the sailing season. If you have repairs or damage to your boat, you should repair these first before applying antifouling.

7. How do I remove antifouling?

Is the existing antifouling in poor condition or do you not know what kind of antifouling is currently on your boat? Then we recommend removing the antifouling completely. You can remove antifouling in several ways:

Remove antifouling with a vacuum scraper

You can easily remove antifouling by sanding, spraying or scraping your boat with, for example, a vacuum scraper. Moreover, this 1-component paint stripper is suitable for use on polyester without damaging the gelcoat.

See also the information article on sanding your boat

Antifouling removal with Interstrip AF

International Interstrip AF is specially formulated to remove antifouling from all surfaces. In addition, this 1-component paint stripper is suitable for use on polyester without damaging the gelcoat.

More information about antifouling?

Do you have more questions about antifouling or need advice on the right antifouling for your boat? Feel free to contact our specialists. You can do so on working days by phone, emailWhatsApp and live chat. We are happy to help you and provide expert advice without obligation!


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