How To Waterproof a Plywood Boat Using Wood Sealant or Paint?
Waterproofing your plywood boat is probably the most essential step before you start using it in water for all sorts of fun activities.
Although most plywood boats already have some extent of waterproofing ability, it is not enough to save the wood from the constant damaging effect of water.
Hence, it is always recommended to apply additional layers of protection to enhance the longevity and water-resistivity of the boat.
If you have a plywood boat that you need to waterproof, then this post is all you need. Figuring out how to waterproof your plywood boat by exploring the internet can be challenging because there are too many methods.
To avoid this confusion, we have compiled the best tried and tested ways to waterproof plywood boats from the internet, along with their step-by-step procedures.
What Type of Plywood Is Used for Boats?
The most suitable plywood for boats is marine plywood. What makes it the best choice? Plywood is, in simple terms, multiple layers of wood veneer glued together with a strong adhesive.
Marine plywood is a particular type of plywood that not only has more layers of wood veneer than others, but the adhesive it uses is also superior in terms of moisture blocking and adhesive property.
Due to this reason, marine plywood has a higher threshold for moisture exposure and is highly durable while being lightweight. In fact, it is regarded as the highest-graded plywood.
Since boats require extremely waterproof and sturdy materials, there is no match for marine plywood in the boat construction industry.
However, despite their highly water-resistant nature, marine plywood without external waterproof coating will begin to show signs of delamination after regular use as, besides water, UV exposure can also be highly damaging.
Thus, waterproofing is one step you should never avoid as it also serves as a protection layer against UV rays.
The best part is that when you need to waterproof your plywood boat, you need not hire a professional. You can waterproof your plywood boat easily at home if you know what steps to follow. Let’s now look at the ways you can waterproof plywood boats:
How To Waterproof a Plywood Boat Using Wood Sealant?
Applying wood sealer is apparently the best method by far. It is extremely easy to apply and creates a stubborn coat against moisture, dust, UV damage, etc. Hence, significantly increasing the durability of the plywood.
Using a wood sealant involves applying an epoxy layer. The special virtue of epoxy is that it is absorbed deep into the wood and provides two benefits.
First, it enhances the waterproof ability of the wood. Second, it allows the waterproof paint to stick on the surface efficiently. If you apply the wood sealant properly, it can make your plywood boat last for more than thirty years.
Required Material:
Applying a wood sealant is indeed an easy method but a tedious one. Thus, it is vital to gather all the required materials beforehand to avoid a mess. You must have the following materials for this method:
- Wood fillers.
- Putty knife.
- Sandpaper.
- Acetone.
- Towels or clean pieces of cloth.
- Wood sealant.
- Clear epoxy.
- Roller or foam brush.
- Spray-on or paint.
Step by Step Process:
Now that you gathered all the required materials in one place, let’s get into action:
1. Apply the wood filler
The first step is prepping the plywood. This involves smoothing the surface using wood filler, sanding down, and cleaning the surface.
In some instances, the plywood you bought may be uneven. Thus, a wood filler is required. A wood filler fills the holes on the surface, making it even and smooth for lucrative and effortless application of the sealant. You can get any wood filler of your choice.
The best tool to apply wood filler is the putty knife. The wood filler can be either used directly on the surface or after mixing with a hardener for a better finish. If you have premium plywood that has a smooth surface, you can skip this step.
2. Sand plywood
To further smoothen the surface, sand down the plywood. Sanding removes the exterior layer that results in even application, and the sealant sticks better to the plywood. Any 80-grit sandpaper will efficiently remove all the unevenness of the wood.
Ensure that you sand all the sides of the wood, including edges, to fully prepare it for the sealant. Continue to sand down the surface until you are sure that the surface is free from dust and debris.
3. Clean the plywood
After sanding, minute particles of dust and debris will be left on the surface. You need to thoroughly clean the surface before applying the sealant; otherwise, it will result in an uneven coating.
Take a towel completely saturated with acetone. Rub the towel on the plywood and leave it to dry for a few hours.
Water will also work well in cleaning the plywood. Use a dampened piece of cloth to get rid of dust from the surface.
4. Apply the wood sealant
Once the plywood is prepped, it is time to apply the wood sealant. There are plenty of great wood sealants in the market.
You can choose any wood sealant that is designed for marine plywood. We recommend the SEAL-ONCE MARINE as the buyers claim it to be an excellent choice.
| Photo | Product | Buy |
|---|---|---|
 | SEAL-ONCE Marine Penetrating Wood Sealer and Waterproofer, Clear, 1 Gallon | Check Price On Amazon |
The method you use to apply the water sealant depends on the product. Most sealants can be applied using a synthetic brush. Still, you must consider the instructions provided by the manufacturer to determine the best tool to apply.
If you are applying a second coat, apply it when the first coat has penetrated into the plywood but is not completely dry.
The water sealant must be left to dry for at least a day before applying any other layer to it. You might notice a change in the tint of the plywood, but it is nothing to worry about.
5. Coating with clear epoxy
Applying clear epoxy to marine plywood is the most critical step of the process because it is the coating that will affect the durability of the plywood to a great extent.
Pick a reliable and high-grade epoxy resin such as Pro Marine Top Epoxy Resin. Foam brush and roller will work equally well for applying the epoxy. Ensure that the coating is even throughout, taking extra care about sealing the edges.
Apply the second coat only after the first layer is completely dry. You can add as many layers of epoxy as you want. However, the minimum required layers should be equal to the layers of the plywood. After every layer, gently sand the plywood for an effortless application.
6. Apply paint
If it was for any other application, applying paint may not have been necessary. However, for boats, having as many layers of protection as possible is better. Moreover, the paint will also add visual beauty to your boat.
Use premium outdoor paint for this step. Apply the paint using whichever tool you find most convenient. Once the first coat is completely dry, proceed to apply the second coat. Let the paint dry, and now you have an extremely durable and waterproof boat ready to hit the waters.
Precautions:
- When cleaning the plywood with acetone, make sure that the surface is completely dry before applying the sealant, as acetone can influence its properties.
- Wear appropriate safety gears such as goggles, gloves, clothing when handling epoxy resin.
How To Waterproof a Plywood Boat Using Latex-Based Paint?
The following method is probably more convenient than the first method, but it is also less reliable. Therefore, it is more suitable if you do not use the boat regularly.
This will increase the durability of the boat adequately. However, after prolonged abuse and exposure, it needs to be renewed.
Required Material:
- Sandpaper.
- Towel or pieces of cloth.
- Latex-based primer.
- Latex-based paint.
- Brush or roller.
Step by Step Process:
1. Sand down the paper
Before applying any coating on the plywood, prepping is crucial. Use sandpaper to remove the external layer and even out any imperfections on the surface.
Sand the plywood until the entire surface is smooth. Afterward, clean the surface with a damp cloth to remove the sawdust and debris. Wait for the surface to dry completely before proceeding to the next step.
2. Apply primer
The first rule that you should know about applying latex-based paint is that it needs a primer. The primer has many benefits. It provides better adherence for the paint, adds durability, and gives a smoother finish after painting.
Pick a high-grade latex-based primer and apply a thin layer using a brush. Give ample time for the primer to dry before you apply a second coat if required or the paint.
Before applying each layer of the primer, lightly sand the surface and clean it with a damp cloth to facilitate application. Allow the primer to parch for a couple of hours and then proceed to the next step.
3. Apply latex-based paint
You can choose any high-quality latex-based paint that is ideal for marine plywood for this step.
It comes in different finish types such as gloss, matte or semi-gloss, and it is entirely up to you which one you pick. Although there are certain factors, you must consider while choosing the finish type.
The gloss finish is the most durable type of finish, but the imperfections of the surface are easily visible. The most practical choice is semi-gloss. It is almost equally durable as gloss and also hides imperfections well.
If you are unsure which paint to buy, pick the Rust-Oleum Marine Topside Paint, as it is specially designed for boats.
| Photo | Product | Buy |
|---|---|---|
 | Rust-Oleum 207005 Marine Coatings Topside Paint, Quart, Battleship Gray | Check Price On Amazon |
Use a roller or brush to spread a thin layer of paint. Do not completely saturate the brush with paint because it will lead to dripping.
Let the paint dry, which will take two to four hours depending on the brand, before applying another coat over it. You can apply as many paint coatings as you feel, but a minimum of two is necessary.
Once this step is complete, your boat will be ready to use.
Precautions
- Paint and primers may have harmful fumes. Hence, always wear proper protective gear such as gloves, glasses, and full sleeve shirts while painting.
Marine plywood is indeed the number one choice for boats due to its high strength and waterproof properties. However, it is not wise to expose marine plywood to water right after buying it from the store.
You can build a boat from marine plywood without waterproofing it. Still, without adding additional layers of waterproofing, it will delaminate sooner than expected.
Hence, you will need to introduce a few layers of water sealants or paint to increase the boat’s lifespan. Hopefully, this article provided you with information to achieve the level of durability you need in your boat.
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