Polyester Resin For sealing wood???

[cooper.bohner]

Hey guys. Currently working on restoring my 1988 stratos bass boat, (another thread available talking about that build). But I am getting close to getting the subfloor in and it does need to be sealed. The original plan was to use regular epoxy but I have quickly discovered that will get expensive fast. So started looking at alternatives being that the sub floor will be almost completely covered and the slightly exposed part will be covered in a foam decking. That being said I have found polyester resin to be significantly cheaper. But I have herd mixed results, mostly glassing with it to wood. I have herd to dilute it 5:1 with acetone to allow it to soak into the wood. So personaly I don't see its "bond" to the wood being a big problem being its under very little pressure or load. I should add that the edges of the subfloor will be fiberglassed with west systems and 1700. That being said table top resin is also a lot cheaper but I'm pretty sure its just polyester from the slight research I have done. Any advice to sealing the subfloor for a slightly more affordable option would be greatly appreciated because spending $800 on west systems just for a sealer isn't quite ideal.

[Fx20 2011]

Nice build thread you have going. I'm currently on my third boat rebuild. I bought each with a rotten floor and transom. In addition I have rebuilt other boats for friends. Honestly there are a lot of opinions. Everyone has their favorite and can justify the product they use. I have done it all including a full glass cover. Today I have settled on just one product and procedure. I just use three coats of marine spar, I prefer the the spar urethane for boat decks and transoms. You can find it at Lowes or Home Depot.
It's is fast and easy and long lasting. Let's just say none of my work has failed in 25 years. Good luck on what ever product or procedure you go with.

[Fx20 2011]

20230107_165305~2.jpg

This is what three coats of spars looks like on the transom. I'm hoping to have this transom done at the end of this week. I'm still waiting for some through the hull hardware to hook up my livewell. The two are tor my high-low and standard bilge pumps.

I can post a picture of the treated floor if you like, it hasn't been installed yet. I just need to move things.

[cooper.bohner]

Appreciate the reply, and that's good info to know. Ill probably end up coating the underside of the plywood with that and all the spots that should hopefully never see water. I will probably stick with epoxy for the small portion of the deck that is exposed constantly but that will help out a ton.

[Mike D.]

Spar urethane will not give a good bond for glassing over wood, or to other fiberglass ! IE hull or other parts of your boat/hull ! If you use acetone or styrene to dilute it will penetrate better, and also will make so the new work you are doing will bond correctly ! Ideally you should use styrene as that is the solvent used to make glass resin ! When you use dissimilar resins, IE like epoxy they have different expansion, and contraction rates ! If polyester resin was used to built the hull you should, or at least be better advised to use similar products !

[cooper.bohner]

Good to know, I ended up picking up another thing of west systems just because I know its tried and true so that will be used to coat the sub floor after all. Now for the hull, I'm pretty sure it is epoxy since the spots I have sanded are a brownish color very similar to the color of west system hardener. But that is really good to know about keeping the resins matching or close to.

[Scott S.]

I've built a lot of boat's, new not rebuilt. We always cover the entire piece of plywood, in some cases like ski lockers we would put a layer of fiberglass on the under side, wet ski's egauls humidty. If you have anything that drains down the keel, like a TM tray then it will cause humidity. If the wood isn't protected it will suck up that moisture, delaminate and then you're putting your foot through it.

[stinkus]

For $800, that is a lot of epoxy. We're talking gallons for that price. How big is the piece of plywood? Roughly half a sheet +/-? The last time I bought a quart kit of west system, last year maybe, it was under a $100 easily. If not half that. But, I work at a boatyard and get stuff at cost plus tax.

You can use poly or vinyl to "seal" wood. But, in my opinion, their porous and will still absorb moisture. An epoxy would be the best option for longevity. With most epoxy systems, you can roll on a coat, wait till it tacks up, and apply a second coat. That's how I do it at work and on my own boat.

[cooper.bohner]

So that number was based on a total boat epoxy coverage calculator that I'm thinking is a little off the more I use the stuff. For me a gallon of west systems is $100 and 160 with the resin. The sub floor is probably around 50 square feet but that's just a guess it took a little bit under 3 sheets of plywood but with some scrap so probably 2.3 sheets. So probably one gallon would coat one side if I just had to guess, but I guess only one way to find out. And to reply to Scotts comment the plan is for no water to hopefully ever get into the keel area. Gonna have a sump style system is the best way I can describe it for water drainage.