How Dry Docking Impacts Your Boat's Antifouling Protection

Antifouling is a paint coating used to protect the hulls of boats from organisms that can cause harm. It is most commonly used on the hull, but it can also be used on drive shafts and propellers that are continuously in the water. Antifouling is necessary to prevent the growth of organisms such as barnacles, mussels, and tube worms, which can increase drag, reduce fuel efficiency, and impact the performance of the boat. The type of antifouling used depends on the speed of the boat, the material of the hull, and the waters it will be sailing in. Proper application of antifouling paint can give faster sailing, reduce fuel consumption, and lower environmental impact.

Hard antifouling: A hard surface ideal for fast motorboats, trailer boats and boats in dry marinas

Hard antifouling is a type of bottom paint that is ideal for boats that are regularly taken out of the water, such as trailer boats, or that are stored on dry land, as well as high-speed vessels such as racing yachts and motorboats. It is also more suitable for boats in low-fouling areas.

Hard antifouling is more effective at repelling marine growth than soft bottom paint due to its higher level of biocide. It also offers a rigid, smooth surface with an excellent finish, which is beneficial for racing boats.

However, hard antifouling is more expensive than soft bottom paint and is not suitable for boats that are regularly trailered or taken out of the water. This is because hard antifouling quickly oxidises when exposed to air, reducing the efficacy of the biocides.

If you are considering hard antifouling for your boat, it is important to prepare the hull surface thoroughly. This includes giving the hull a good jet wash and scrub, and possibly a wet sand, before applying the paint.

Some popular options for hard antifouling paints include:

• International Ultra 300
• Hempel Hard Racing Antifouling
• International Trilux 33
• Seajet 037 Coastal

Self-polishing antifouling: A polishing effect ideal for sailing boats

Self-polishing antifouling, also known as self-polishing copolymer (SPC), is a modern technique that uses a copolymer binding agent to trigger a controlled chemical reaction on the paint surface in the water. This reaction ensures a constant and low rate of biocide release, protecting your boat from fouling. SPC is water-soluble, becoming thinner as you pass through the water, ensuring a fresh coating of biocide on the surface.

Self-polishing antifouling is ideal for sailing boats as it provides a polishing effect, ensuring the boat's performance is maintained. It is not recommended for fast sports boats as the rub-off can be too strong, completely dissolving the coating.

The application method for self-polishing antifouling can be either with a brush or roller. While a brush is ideal for accessing difficult areas, a roller ensures an even spread of the antifouling over a larger area. It is important to ensure the surface is dust and grease-free before application.

Some popular self-polishing antifouling products include:

• Seajet Shogun 033
• Seajet Emperor A 034
• International Micron 350
• Hempel Mille NCT
• Seatec Standard Pro

Semi-polishing antifouling: Prevents the build-up of thick layers, suitable for fast boats

Semi-polishing antifouling is a type of antifouling paint that prevents the build-up of thick layers of paint on a boat's hull. It is ideal for fast boats as it helps to maintain a smooth hull, which reduces friction with the water and improves the boat's speed and fuel efficiency.

Semi-polishing antifouling, also known as self-eroding or ablative antifouling, is one of the most common choices for DIY application. It can be applied using a roller or brush and contains organic and non-organic compounds such as copper, zinc, and booster biocides suspended in a resin or solvent-based formulation. This type of antifouling slowly releases biocides through the paint film, preventing the build-up of thick layers.

The key advantage of semi-polishing antifouling is its ability to maintain a smooth hull finish. As the boat moves through the water, the paint gradually wears away, exposing fresh layers of biocide-loaded paint. This controlled release of biocides helps to reduce fouling and improves fuel efficiency and performance.

When applying semi-polishing antifouling, it is important to follow the manufacturer's instructions and safety guidelines. Ensure the hull is properly prepared by cleaning, sanding, and priming the surface. Use a suitable roller or brush to apply the paint, and allow adequate drying time between coats. It is also important to wear personal protective equipment when working with antifouling paints due to the presence of toxic biocides.

By choosing the right type of antifouling paint and applying it correctly, boat owners can ensure their vessels remain free of harmful aquatic growth, maintain optimal performance, and reduce fuel consumption.

Thin-film antifouling: An extremely smooth surface that makes adhesion harder for organisms, resulting in higher speeds and lower fuel consumption

Thin-film antifouling is a type of protective coating for boats that offers several advantages over traditional antifouling methods. One of its key features is its extremely smooth surface, which makes it harder for organisms like barnacles, mussels, and weeds to attach to the hull. This smooth surface also reduces friction, allowing boats to glide more easily and faster through the water, resulting in higher speeds and lower fuel consumption.

The use of thin-film antifouling avoids the build-up of thick layers of paint, which can flake or peel off over time. It is also quick and easy to apply. From an environmental perspective, thin-film antifouling is favourable as it contains only a small amount of biocides.

However, one limitation of thin-film antifouling is that only the same type of antifouling can be applied on top of it. The smooth surface makes it incompatible with other types of antifouling, so changing the type would require removing all previous layers and starting with a fresh coat.

When choosing thin-film antifouling, it is important to consider the type of hull material and intended waters. It is well-suited for boats sailing in the North Sea, Baltic Sea, and inshore waters. Additionally, legal regulations regarding the use of biocides in certain countries should be taken into account.

Overall, thin-film antifouling is a great option for boat owners seeking improved performance, ease of application, and a more environmentally friendly solution.

Antifouling for propellers: Special antifouling that usually comes in a spray can, making application easier

Antifouling for Propellers

Propellers require specialist antifouling due to the material they are made from and the speed at which they turn. A good primer or tie-coat is also needed when applying to bare metal.

Propeller treatments can be purchased in packages or separately and come in different applications, including:

Spray Cans

Spray cans make application easier, especially when it comes to reaching difficult areas. Antifouling sprays include:

• Seajet Pellerclean: A foul-release propeller coating that is biocide-free and environmentally friendly.
• Trilux Prop-O-Drev: An incredibly hard antifouling formulated for use on outdrives, outboard legs, propellers, and sterngear.
• Nautix A7T.Speed: A hard matrix antifouling developed for propellers and Z-drives.
• Tikal Prop Gel: A teflon-based propeller anti-fouling product that comes in a creamy, very adhesive, soft paste.
• Seajet Emperor: A self-polishing antifouling spray.
• Hempel Ecopower Prop: A biocide-free spray that makes it difficult for fouling to attach to propellers.
• Hempel Silicone Propeller Kit: A biocide-free spray paint that includes a light primer.

Other Applications

• Seajet Propeller Triple Pack: Includes a primer.
• International Trilux Prop-O-Drev Antifouling Spray: Can be used with a primer spray or the primer Cruiser 200.
• International Prop-O-Drev Primer Spray: A primer spray.
• International Cruiser 200: Can be scrubbed or cleaned off mid-season.
• Hempel Hard Racing Boottop: Provides a strong scrubbable antifouling in a range of bright colours.
• Hempel Ecopower Prop: A biocide-free coating that has a self-renewing effect throughout the season and needs to be applied over a primer.
• Marlin Velox Plus: A hard biocidal antifoul paint that can be overcoated each season.
• Propspeed: A silicone-based topcoat that creates an extremely slippery surface and is recommended to be applied by a professional applicator.
• Prop Defender: A glass-reinforced, silicone-based, and hydrophobic product that comes in a two-stage hydrophobic top coat.

Frequently asked questions