Why You Need A Barrier Coat: Protection And Prevention

do I need a barrier coat

A barrier coat is a protective layer that seals the surface of a boat, making it impenetrable to water and preventing blistering. Blistering can compromise the integrity of a boat's hull, so it's important to take steps to prevent it. Applying a barrier coat involves several steps, including surface preparation, mixing the coating components, and applying multiple coats. The process can be time-consuming and costly, so boat owners often wonder if they need to apply a barrier coat. This decision depends on factors such as the age of the boat, the presence of blisters, and the boat's history of blister problems.

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Blisters prevention

Blisters are a common problem for boats, especially those that have been in the water for a long time. They occur when water seeps through the gel coat and enters the fiberglass layers, dissolving the chemicals inside. This solution then attracts more water through osmosis, and as the pressure increases, a blister is formed. Blisters can threaten the structural integrity of the hull, so it is important to take steps to prevent them.

One way to prevent blisters is to apply a barrier coat to the hull. A barrier coat seals the surface and makes it impenetrable to water, preventing blistering. It is important to note that the hull must be completely dry before applying a barrier coat, as applying one to a wet hull can trap moisture and actually speed up the blistering process.

There are three types of barrier coat protection:

  • Preemptive barrier coating on new boats: New boats may come with a barrier coat applied at the factory, along with a blister warranty. If your boat does not have a barrier coat, you can apply one yourself by wiping down the hull with a solvent dewaxer, sanding thoroughly but lightly, and then applying 2-3 coats of barrier coat primer.
  • Blister repair alone: If your boat already has blisters, you can repair them by scuff-sanding over the blisters, opening them up by scraping or grinding away the damaged material, flushing with water, and then sealing the laminate with low-viscosity 100% solids epoxy resin.
  • Blister repair with a barrier coat: If your boat is older, it is important to ensure that the hull is very dry before attempting any repairs. You can do this through natural drying, by artificially warming the hull, or by using a vacuum to draw out the moisture. Once the hull is dry, coat the areas where the gelcoat was removed with unthickened epoxy, fill the holes with epoxy filler, and then apply 4-6 coats of barrier coat material to the outside of the hull.

By taking these steps to prevent and repair blisters, you can help protect your boat and ensure its structural integrity.

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Resale value

When it comes to the resale value of boats, a barrier coat can be a very important factor. A barrier coat is designed to prevent water permeation in a boat's hull. Over time, blisters (osmotic blisters) can appear on boats, threatening the structural integrity of the hull. This is due to water seeping through the gel coat and the process of osmosis, which draws more water into the hull.

A barrier coat, usually made of epoxy or a similar material, seals out moisture better than a polyester gel coat. Applying a barrier coat can protect a boat from osmotic blisters and increase its resale value. It is much easier to apply a barrier coat to an intact hull than to repair blisters and then apply the coat. Therefore, if you are planning to resell your boat, it is advisable to apply a barrier coat as a preventative measure, especially if your boat is in the water year-round or in a warm-water area.

However, it is crucial to ensure that the hull is completely dry before applying a barrier coat. Any moisture trapped in the hull laminate will be sealed in by the barrier coat, rendering it ineffective. This can be a lengthy process, sometimes taking several months, and it may involve using a moisture meter to ensure the hull is dry.

Additionally, it is important to follow the manufacturer's instructions when applying a barrier coat. They provide detailed application instructions, including drying times and the number of coats required to achieve optimal film thickness.

By taking these steps, you can help protect your boat from osmotic blisters and potentially increase its resale value.

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Hull protection

A barrier coat is a protective layer that seals the surface of a boat's hull, making it impenetrable to water and preventing blistering, which can compromise the integrity of the hull. Blistering occurs when water penetrates the gel coat surface of a boat, leading to the formation of blisters that can delaminate the surrounding area and threaten the structural integrity of the hull.

To prevent blistering, it is essential to apply a barrier coat to seal the hull and block water entry. This is especially important for boats with fiberglass hulls, as fiberglass is more susceptible to water permeation. By applying a barrier coat, boat owners can protect their vessels from osmotic blistering and maintain the integrity of the hull.

There are different types of barrier coats available, but epoxy-based barrier coats are commonly used due to their effectiveness in sealing out moisture. When applying a barrier coat, it is important to follow the recommended preparation and application procedures. This includes properly cleaning and preparing the hull surface, mixing the barrier coat components in the correct ratio, and applying the recommended number of coats to achieve the optimal film thickness.

Additionally, it is crucial to ensure that the hull is thoroughly dry before applying the barrier coat. Applying a barrier coat to a wet hull can trap moisture and accelerate the deterioration process. Therefore, allowing adequate drying time, using moisture meters to check for dryness, and following manufacturer recommendations are essential steps in the process.

By taking the time to apply a barrier coat properly, boat owners can protect their investment, maintain the structural integrity of their vessels, and prevent costly repairs associated with blistering and water damage.

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Cost and time

The cost and time involved in applying a barrier coat will depend on several factors, including the size of the boat, the type of barrier coat used, and whether the work is done professionally or as a DIY project.

For professional application, the cost can vary depending on the marina and the extent of the work required. For example, one boat owner reported being quoted around $3,500 to soda blast and apply a new barrier coat to their Catalina 27. This price may be lower if the blistering is limited to the keel rather than the entire hull.

If you choose to apply the barrier coat yourself, you will need to factor in the cost of materials, including the barrier coat product, safety equipment, and any necessary tools. The TotalBoat TotalProtect Epoxy Barrier Coat Primer, for instance, offers a range of application tools and protective gear on its website. The cost of the product itself can vary depending on the brand and quantity required, but a 2-quart kit of TotalBoat TotalProtect can be purchased for around $100.

In terms of time, applying a barrier coat typically involves several steps, including surface preparation, mixing and applying the barrier coat, and allowing adequate curing time. The surface preparation process can be time-consuming, especially if there are existing blisters that need to be repaired. It is important to follow the manufacturer's instructions for curing times, as inadequate curing can lead to improper adhesion and other issues.

For larger boats or more complex projects, it may be more time-efficient to hire professionals who have the necessary skills and equipment to complete the job effectively. Additionally, some barrier coat products may have specific application techniques or requirements that are best handled by experienced applicators.

Overall, the cost and time investment for a barrier coat can vary significantly depending on the specific circumstances and the chosen approach. It is important to carefully consider the benefits of professional application versus DIY, taking into account factors such as cost, time, skill level, and safety.

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Application methods

Barrier coats are applied to prevent water from seeping into the gel coat and causing blisters, which can compromise the integrity of the hull. The barrier coat is applied prior to the bottom paint, and it is important to follow the manufacturer's instructions for the best results.

Step 1: Surface Preparation

Start by cleaning the surface with a lint-free rag and a solvent dewaxer to remove any contaminants such as dust, wax, oil, or grease. For fiberglass or wood surfaces, lightly sand the area and wipe away any residue with a lint-free rag dampened with a solvent. If there are gelcoat blisters, expose them by sanding, then puncture and grind out the affected areas. Rinse and allow the surface to dry completely before solvent-wiping with denatured alcohol or acetone. Apply a filler to each blister and let it cure before sanding and applying the barrier coat.

For aluminum surfaces, sandblast or disc sand until you reach the shiny metal. Remove any residue and wipe the surface with a lint-free rag and a solvent. Apply an aluminum boat etch wash for better adhesion and follow with the barrier coat within one hour.

For steel surfaces, sandblast or grind until you reach bare shiny metal. Remove all residue and wipe the surface with a clean, lint-free cotton rag dampened with a solvent, followed by a dry cotton rag. Apply the barrier coat within one hour of metal preparation.

Step 2: Stir Base and Curing Agent

The base and curing agent components must be thoroughly mixed separately before combining them. Ensure you are using the correct mix ratio, which is typically 3:1 for barrier coats.

Step 3: Combine Components

For small applications, pour the desired amount of the mixed solution into a clean, dry, disposable mixing pot. For larger projects, pour the entire can of curing agent slowly into the can of base.

Step 4: Mix and Allow Induction Period

Use a clean, dry, wooden stir stick to mix the combined components thoroughly. Then, set the mixture aside for about 15 minutes to allow for the chemical reaction between the two components, which is essential for proper curing.

Step 5: Apply the Barrier Coat

You can use a brush, roller, or spray equipment to apply the barrier coat. The recommended number of coats varies depending on the roller cover used, but it is generally between 2 and 5 coats. Ensure you achieve the recommended dry film thickness.

For fiberglass or wood, wipe the surface with a lint-free rag and a solvent immediately before applying the barrier coat.

For steel or iron, ensure the metal is shiny and clean for maximum adhesion, and apply the primer within one hour.

For lead, apply the barrier coat immediately after grinding to shiny metal, as it will quickly oxidize and become dull, affecting adhesion.

For aluminum, apply the barrier coat within one hour of surface preparation to avoid oxidation and dulling.

Step 6: Recoat and Overcoat

To know when to recoat or overcoat with antifouling paint, perform the "thumbprint tacky" test: press your thumb gently into the barrier coat, and if you leave a clean thumbprint, the surface is ready.

Frequently asked questions

New boats sometimes come with a barrier coat applied at the factory, which may include a blister warranty. If your boat does not have a barrier coat, you may want to investigate whether the builder has used specific resins that are resistant to osmotic blistering.

A barrier coat seals the surface, making it impenetrable to water in order to prevent blistering, which compromises the integrity of your hull.

If your boat has bubbles or blisters, or if you've sanded to or see any exposed fiberglass, then it's time to apply a new barrier coat.

Without a barrier coat, water can penetrate the hull and cause blisters, which can threaten the structural integrity of the hull.

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