Got a plywood boat that you’re just finishing up? Perhaps, you’re just doing a reseal of a used wooden boat? If you find yourself in the dark with regards to how to waterproof plywood for a boat, no worries, this guide has got your back.
Whether you’re looking for the cheapest way to waterproof plywood or are aiming for a higher-quality and more long-lasting solution, you can learn every viable method and the steps for each one.
Table of Contents
- Ways to Waterproof Plywood for a Boat
- You’ll Need a Few Tools
- Step-by-step Guides on How to Waterproof Plywood for Boats
- Pros and Cons of Each Method
- Other Ways You Can Consider
- Features and Durability of Plywood for a Boat
- The Importance of Sealing Plywood
Ways to Waterproof Plywood for a Boat
For everyone’s benefit, I’ve chosen to outline two methods that suit the usual needs and requirements when it comes to most marine plywood waterproof projects. By reading this guide, you’ll learn about:
- The Cheap sealant + Latex paint method for people who want an economical but still reliable way to keep the plywood from rotting and splitting apart.
- The Fiberglass Cloth + Epoxy Strategy for guys and gals who prefer the best way to tackle marine plywood treatment (aka the one that will make sure your boat will last for years).
You’ll Need a Few Tools
Cheap Sealant + Latex Paint Method
- Marine plywood sealer (e.g. Loctite PL marine sealant)
- Latex paint
- 80-grit sandpaper or any you find great for finishing
- Cleaning cloth
- Roller and brush
- Paint sticks and towels
- Tack cloth
Fiberglass Cloth + Epoxy Method
- Epoxy resin with hardener
- Fiberglass cloth (high-quality preferably)
- Sandpaper (60-grit,120-grit, and 180-grit)
- Mixing cups
- Stirring stick
- Foam roller
- Cleaning cloth
Step-by-step Guides on How to Waterproof Plywood for Boats
Pros and Cons of Each Method
Sealant + Latex
- Relatively easier to do
- More budget-friendly
- More manageable overall
- While latex can make plywood water resistant to a degree, it will inevitably wash out quickly if exposed to moisture consistently.
- Only a short-term solution
Fiberglass + Epoxy
- For its ability to guarantee long-term durability and usage of the boat you built, many consider this the best DIY technique to waterproof and weatherproof plywood.
- Highly resistant to physical damage and the elements
- Works well with any kind of plywood
- Improperly mixed epoxy can result in soft spots.
- Chopped strand mat, which is the cheaper fiberglass type, does not work with epoxy resin.
Other Ways You Can Consider
- If you find fiberglass to be a bit overpriced in your area, you can try the popular poor man’s fiberglass method laid out here.
- You can also look into marine sealing tapes, although I admit that I haven’t tried them yet.
Features and Durability of Plywood for a Boat
- It may not be as water-resistant as cedar, but it can take a lot of punches, figurative or otherwise, and is highly shock absorbent. Any hardwood plywood balances strength and durability almost perfectly, with those made of Baltic birch being excellent example
- Amenable to being waterproofed and resistant to fire.
- Out of all the wood choices out there, plywood wins in keeping weight down.
- Highly pliant, which makes it a great material for hulls.
- Cost-effective, since plywood’s available in various sizes and have wide coverage.
- A breeze to handle (and sand), which is why it’s a favorite among boatbuilders.
The Importance of Sealing Plywood
Boat builders use epoxy sealer for marine plywood because they don’t want to have all their efforts of making their babies go to waste.
If you don’t regard what you created as just some “prototype”, but rather similar to a child that you birthed with your own hands, then I assume you’ll be more likely to want to ensure it will last for decades, right?
Can you endure the thought of the sun’s harsh UV rays beating down on it? Or high humidity and not hauling the boat out of water, which will almost always result in rot?
That’s why, to me, anything you own that’s made of plywood and meant for outdoor use should be sealed, especially the boats you made from scratch.
As far as how to waterproof plywood for a boat goes, you can choose between two routes.
One will be easier on your wallet but tends to only be a temporary solution. The other, while costing more, will give you better peace of mind with regard to your creation’s expected mileage.
Weigh your options based on your needs and remember all the pointers I’ve given here to avoid potential mistakes.
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