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Antifouling your boat – all your questions answered

When you have parted with a significant amount of your hard-earned money to purchase the boat of your dreams, you’ll understand just how important it is to maintain the value of your vessel. The most obvious way to achieve this is to ensure that you have a regular maintenance plan in place to protect your boat. In this article, Richard Snowball, our Marina Manager, answers all the key questions surrounding antifouling.

Table of Contents

What is antifouling?

Do I need to antifoul my boat?

How often should I antifoul my boat?

What are the different types of antifoul paint?

What antifoul paint do you use at Val Wyatt Marine?

What is the process for antifouling a boat?

How much does it cost to antifoul a boat?

What is antifouling?

Antifouling is the process of applying a special protective paint to the bottom of a boat to protect the vessel from marine growth, such as algae and barnacles. The coating is typically applied to the hull, as well as the rudder, avoiding anodes, speed and depth transducers and skin fittings.

Do I need to antifoul my boat?

Antifouling your boat should play a key part in any maintenance programme. Whilst a considerable amount of time might be spent cleaning a boat during the summer, the bottom of the vessel will remain submerged under water for many months – and it is only when the boat is removed from the river or sea that antifouling can take place. Therefore, the winter is the most common time for this type of maintenance to be carried out.

Unwanted marine growth on the bottom of a boat can dramatically slow the speed and performance of your vessel, whilst also increasing fuel consumption by as much as 30%. It is obviously unpleasant on the eye too.

How often should I antifoul my boat?

The frequency of applying antifoul to your boat depends on several factors, such as location and usage – however, boats that are afloat on the water for prolonged periods should be regularly checked to determine whether the protective coating needs to be reapplied. Vessels that are regularly lifted out of the water during the season, and subsequently cleaned with a jet wash, may only need antifoul applied once every few years.

What are the different types of antifoul paint?

There are a number of different options available when it comes to selecting antifoul paint:

Hard antifoul paints 

When applied correctly, a hard antifoul paint, also known as contact leaching paint, will continuously release biocides through the film of the paint. As a result, this antifoul will not wear away like the softer alternatives. You are most likely to see this type of paint applied to higher speed vessels, where performance is key, as well as boats on dry moorings due to its durability.

Eroding antifoul paints

Eroding antifoul paints, also known as self-polishing coating (SPC), is a softer coating that is specifically designed to erode fairly quickly to ensure that an active layer of biocide is constantly present on the vessel’s surface. This erosion will guarantee a consistent performance across the season, whilst also preventing a long-term build-up of antifoul paint on the boat itself.


Which antifoul paint do you use at Val Wyatt?

For consistency, we standardise the paint we use across the boats we work on. The list consists of:

Hempel Tiger Xtra

This is a high performance, conventional, erodible antifouling providing excellent protection all season. It comes in a variety of colours too. We use this on all the boats except our Interboats and Intercruisers.

International Interspeed Ultra 300

For our Interboat and Intercruiser range, we recommend the Ultra 300, which provides premium performance even in the harshest of environments. This antifoul is applied on those particular boats at the factory, so we prefer to use it for consistency purposes.

What is the process for antifouling a boat? 

There is a specific process that will need to be followed to antifoul your boat in the most effective and efficient way – and much like decorating a house, the key is in the preparation.

Firstly, when a boat is removed from the water, you will need to jet wash the vessel in order to remove the marine growth and slime, as well as using a scraper or a broom for those stubborn bits. Next, you will have to remove the parts of the existing antifoul coating that are beginning to flake off, to ensure a smooth surface and there are no cracks. When happy with the surface, it is important to use masking tape along the waterline. We recommend a second pair of eyes and hands when doing this, to help keep the masking tape as straight as possible and to protect the overall look and integrity of the boat. Now it is time to apply the antifoul paint, using a combination of a roller and a paintbrush. A roller will be suitable for applying 90% of the coating, however there are areas around the waterline and the chocks where it would be benefit from the accuracy of a paintbrush. When painting, do not apply the antifoul too vigorously or attempt to stretch that tin of paint too far. Remember to remove the tape whilst the antifoul paint is still wet – if you leave the masking tape on overnight it becomes incredibly difficult to remove.

Even though antifouling paint will erode and flake away over time, and it is common practice to paint new coats on existing layers, there will be some years where a boat owner may choose to completely strip back the multiple layers of antifouling paint.

It is important for boat owners to be aware that antifouling dust can be extremely toxic, and therefore we highly recommend wearing full protective clothing, including goggles for the eyes and a specialist facemask. DIY options for removing antifoul include chemical stripping or wet sanding, whilst many people also opt for using a blasting contractor to save time.

How much does it cost to antifoul a boat?

The final price will be dictated by the size of the boat and also the condition of the vessel. At Val Wyatt, the standard price for our antifouling service is £36 per metre, exclusive of paint and materials costs.

Over recent years, a number of alternative options to antifouling paints have been explored. The most common antifoul so far has been Ultrasonic Antifouling, which is the process of using a dedicated system to generate electronic sound pulses which keep vessels free of marine growth.

The benefits of this include fewer lift outs (as less cleaning and reapplying is required), savings on fuel and maintenance costs, plus a reduced impact upon the environment. We are looking forward to exploring this innovative new technology in the future.

If you have a question on antifouling, or any of our other marina services, please contact our friendly and experienced team here, or call 01189 403211.