A Comprehensive Guide to Antifouling with Viking Marine

A Comprehensive Guide to Antifouling with Viking Marine

While your boat sits in the water, barnacles, mussels, algae, seaweed, and other aquatic life forms are all vying for a new home on your boat's hull. The result? Poor sailing performance, inefficient boat handling, and increased fuel burn. At Viking Marine, we understand the trials and tribulations of maintaining a clean hull in Irish waters. Let's explore the essential practice of antifouling to ensure your vessel stays shipshape.

Choosing the Right Antifoul:

Selecting the appropriate antifouling product depends on hull material, usage patterns, budget, and maintenance frequency. In general, there are two primary categories of antifoul: self polishing antifoul, and hard antifoul.

  • Self Polishing Antifoul: also called soft or self-eroding antifouling.
  • Hard Antifoul, commonly known as scrubbable or burnishable antifouling.

Simply put, self polishing antifoul is more suitable for cruising and hard antifoul is better for racing. 

Self Polishing Antifoul

In the case of self polishing antifoul, as the boat moves, the antifoul erodes, revealing new biocidal elements, which repel the growth of organisms against the hull, and remove any which may have already begun to grow. This process ensures a consistently smooth surface of your hull, resulting in a lower accumulation of organisms compared to hard antifouls. Self polishing antifouls are particularly suitable for yachts and are generally recommended for boats travelling at speeds below 20 knots. They should also be used on boats that are being used fairly regularly, as the movement of the boat through the water is what activates the erosion and keeps the antifoul functioning. Self polishing antifoul won’t be effective if your boat is sitting on a slip or a mooring all season long. If you are in need of self polishing antifoul, have a look at a few of our options; Seajet 033 Shogun Self Polishing Antifoul, International Cruiser 250, and International Micron 350

Seajet 033 Shogun


International Cruiser 250


 International Micron 350

 Hard Antifoul

Hard antifouls operate by releasing biocides from their surfaces to discourage the growth of fouling organisms. The rate of biocide leaching decreases throughout the lifespan of the product. After several seasons, there might be a residual accumulation of the coating that requires removal. For high-speed or regularly used fast boats, hard antifouling is typically the most suitable choice. At Viking Marine, we offer International Ultra, International VC Offshore, Nautix A4 T.Speed Hard Matrix Racing Antifouling, among others. 

International Ultra


International VC Offshore


Nautix A4 T.Speed Hard Matrix Racing Antifouling

 Seasonal considerations for antifouling in Ireland:

  • Weather and Seasonality: Apply antifoul during a season when your boat is not exposed to harsh weather conditions. Avoid applying antifoul when your boat is likely to be rained on or exposed to extreme conditions, as this can activate erosion and reduce its effectiveness. 
  • Boating Season: Determine when you typically use your boat. If you use your boat for approximately 6-8 months of the year, apply antifoul as close to the start of your boating season as possible. This ensures maximum protection during your active boating months. 
  • Antifoul Lifespan: Consider the expected lifespan of your chosen antifoul product. If your antifoul has an expected life of 8 months, plan your application accordingly to align with your boating season. Applying it too early may result in reduced effectiveness by the time you start using your boat regularly.

DIY antifouling vs Professional Services: 

Consider performing antifouling yourself, as it's feasible for most boat owners. This allows you to inspect the underside of your hull thoroughly. While applying antifoul, take the opportunity to examine the hull for cracks, erosion, or scratches. This proactive approach helps identify potential issues early on and prevents further damage. If you decide to hire a professional for antifouling, ensure they include a thorough inspection of the hull as part of their service. By incorporating these steps into the antifouling process, you not only protect your boat from fouling but also ensure the integrity of its hull by promptly addressing any underlying issues when the boat is out of the water and easier to repair.

Freshwater and Saltwater

What sets apart freshwater and saltwater antifoul? Generally, freshwater environments experience less marine growth compared to saltwater. Consequently, bottom paint formulated for freshwater applications tends to contain fewer active ingredients like copper and zinc, which are aimed at inhibiting growth. At Viking Marine we offer Boat Guard, specifically designed for use in freshwater.

 International Boat Guard

Best Practices for Application:

Applying antifoul is an art in itself, and Viking Marine is here to guide you through the process. From surface preparation to selecting the right PPE, our tips ensure a smooth application and cleanup. We all know Irish weather can be unpredictable, so choose a dry day with minimal wind for the best results.

Environmental Responsibility:

Antifouling isn't just about protecting your yacht; it's also about safeguarding the environment. Viking Marine emphasises responsible disposal practices to prevent harmful chemicals from entering the sea or groundwater. From containing spillages to proper PPE disposal, we support and promote eco-friendly antifouling practices. Currently, the EU's REACH program and the Biocidal Products Regulation (BPR) decide which chemicals can be used in products sold in EU countries. They aim to keep people and the environment safe. All antifoul products sold in Viking Marine fully comply with this regulation. We also offer a completely biocide free option; Seajet 021 Eko Environmentally Friendly.

Seajet 021 Eko

Dos and Don'ts:

To ensure a successful antifouling job, follow these dos and don'ts provided by Viking Marine. From correct area identification and preparation to using the right quantity of paint, these guidelines guarantee a professional finish. Always adhere to the specified timeframes for recoating and relaunching to maximise the effectiveness of your antifouling efforts.


Prepare the Underwater Areas Correctly:

International Interstrip

Prime Hull
  • In many cases, you may need to apply a primer before using your antifoul, such as if you are covering a bare hull, or if you have previously used a different kind of antifoul than the one you are using now. Use Primocon to prepare your hull for antifoul.


International Primocon

Stir Paint Well Before Application:

  • Achieve a homogeneous coating by stirring the antifouling paint thoroughly before application.

Replace the Lid While Temporarily Not in Use:

  • Preserve the integrity of the antifoul by promptly replacing the lid when the paint is not in use, even a few minutes exposed to the air can hamper the performance of your antifoul. 

Apply an Extra Coat at High-Wear Areas:

  • Enhance protection by applying an additional coat of antifoul to areas prone to high wear, such as leading edges which will have more friction with the water.

Apply Correct Quantity of Paint:

  • Refer to the instructions on your antifoul for the recommended thickness, number of coats, to ensure application of the correct amount of paint.

Re-launch Within the Specified Time Period:

  • Adhere to the recommended time frames for re-launching your boat after applying antifoul to maximise its effectiveness.

Wear PPE

  • Safety precautions require the use of safety spectacles, goggles, or visors, in addition to nitrile rubber gloves. You should ensure no skin exposure, and also wear either a solvent mask or a respirator, depending on the space you are operating in. 


Don't Apply Over Salt-Contaminated Surfaces:

  • Avoid applying antifoul over surfaces contaminated with salt to ensure proper adhesion and effectiveness.

Don't Apply Over Unprepared Substrate:

  • Proper surface preparation is crucial for optimal results.

Don't Apply Without Stirring or Mixing:

  • Ensure that antifoul is adequately stirred or mixed before application to maintain homogeneous consistency and effectiveness.

Don't Apply Over/Under the Recommended Spread Rate:

  • Adhere strictly to the recommended spread rate to achieve the desired level of protection and prevent overuse or underuse.

Don't Leave Original Can With the Lid Off for Long Periods:

  • Prevent the degradation of antifoul by avoiding prolonged exposure of the original can to air; keep the lid securely closed when not in use. It may be helpful to pour a small amount into a secondary container to avoid the antifoul in the can being exposed to the air. 

Don't Use Dirty Brushes or Semi-Dried Roller Sleeves:

  • Avoid the use of dirty brushes or semi-dried roller sleeves, this will ensure a smooth finish. Proper maintenance of tools is just as important as proper maintenance of your boat! We recommend Dynex Rollers or Mofab Roller Sleeves for the application of antifoul, while more expensive than basic foam rollers they are much more efficient at evenly distributing heavier paints like antifoul, saving far more in paint value than the cost of the roller sleeve itself.


Don't Recoat or Re-launch Outside the Specified Time Periods:

  • Follow the specified timeframes recommended for your product for recoating and re-launching to optimise the performance and durability of the antifoul.


At Viking Marine, we understand the unique challenges Irish sailors face when it comes to antifouling. Our commitment is to provide you with the knowledge and products necessary to navigate Irish waters successfully, with a clear understanding of how to maintain a clean and well functioning hull. As always, please give us a call or visit our shop with any questions you may have. Click here to view our complete collection of antifoul.

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