Epoxy Resin usage for floor and front deck plywood (with carpet overlay)

[ThaRealBigBen]

I'm trying to figure out how much is overkill for using epoxy resin on subfloor and front deck replacement for a 1989 Bass Tracker Pro 17. I found a place in Florida that sells epoxy resin for much cheaper than some other places, so I've been talking to one of their "tech" guys asking all of my rookie questions about how to apply, etc. From talking to him, I seem to have discovered there is more to this job than I originally thought and that I now need even more epoxy/materials than I originally expected. Here's some of the facts and let me know if this all seems right:

- I basically need to cover a little less than 1 & 1/2 sheets of 4' x 8' plywood (1/2" thick exterior grade) once this is all said and done

- I want to get coverage on both sides of the plywood to be extra sure, but I understand I can get away with just a single coat on the bottom, so I'll do that

- As for the top of the plywood, I've now also been told by the tech guy that it would be highly recommended to add 1 1/2 oz chopped mat when applying the epoxy to the top and to do two layers. The purpose is to add rigidity especially for the 1/2" thick plywood which will reduce "flex from the 200 to 250-lb men these days" that will be stepping on the flooring/deck and which should also prevent chipping away of the epoxy, etc.

The chopped mat usage significantly adds to the epoxy usage I was expecting (due to need for "wetting" the mat), so I've now gone from about 1 gallon epoxy (original expectation) to 3 gallons by his estimates, which costs $184 for just the epoxy and hardener. Basically, I previously had no idea about using the chopped mat and that has now "upped the ante". Once I add in all the other materials needed for mixing/applying, the chopped mat, and shipping, the price ends up at nearly $300 which is more than I was anticipating.

Questions:

Do I really need the chopped mat?
I think the boat previously had 1/2" plywood, so I was trying not to stray from that or add much further weight, but maybe I was wrong? I think using the epoxy/chopped mat is going to add the extra weight anyway, right?
Maybe I can go with thicker plywood which might reduce the amount of added structure (epoxy/chopped mat) needed?

 

[Woodonglass]

Not sure what company you were talking with but...it's usually NOT recommended to use Chopped Strand Mat with epoxy. CSM is mainly recommended to be used with Polyester resin. Epoxy can be used by itself to seal plywood and If you want to enhance the strength you could use a 6oz fiberglass fabric. ($50 bucks worth will cover all your plywood.)
3 gallons sounds about right. You have to use glass to tab the floor/deck to the sides of the hull so you will need at a minimum some 6" glass tape. Again you can use CSM but it offers little to NO strength to the resin and is NOT generally recommended when using Epoxy regardless of what the tech said!!!:nono:

 

[ThaRealBigBen]

Not sure what company you were talking with but...it's usually NOT recommended to use Chopped Strand Mat with epoxy. CSM is mainly recommended to be used with Polyester resin. Epoxy can be used by itself to seal plywood and If you want to enhance the strength you could use a 6oz fiberglass fabric. ($50 bucks worth will cover all your plywood.)
3 gallons sounds about right. You have to use glass to tab the floor/deck to the sides of the hull so you will need at a minimum some 6" glass tape. Again you can use CSM but it offers little to NO strength to the resin and is NOT generally recommended when using Epoxy regardless of what the tech said!!!:nono:

Thanks for the Input, Woodonglass. I think I see why he's recommending the CSM. The website has a discontinued epoxy-compatible CSM and there's now a message with it saying "Owens Corning has discontinued this item. We are continuing to look for other sources. We have found our brand of 1-1/2oz x 50" (cat# FG-10550) regular chopped strand mat wets out with epoxy very well and could be considered a substitute." So, apparently they have discovered the regular stuff also works well with epoxy. I did a little reading and apparently CSM often has an additive that reacts with polyester resins or vinyl, but not with epoxy, so maybe either this stuff doesn't have that additive or presence of the additive is inconsequential for the epoxy?

Also, you mentioned needing to tab the floor/deck to the sides of the hull, but that wouldn't be the case for me. Maybe that's the case for certain types of boats (like fully wooden ones), but I'm simply constructing sections that I would carpet, then screw to the stringers in my aluminum hull. Let me know if I'm missing something or if there's another reason I would absolutely need the fiberglass tape.

Lastly, I spoke to the tech guy again and brought up the thought of using thicker plywood and he seemed okay with that idea saying I could then use a single layer of mat (and therefore also less epoxy at ~ 2 gals). I didn't quite get his affirmation on whether 5/8" would be thick enough for that or if I would need to go to 3/4" though, so I'll figure that out. He seems to just be adamant that a lot of boats have so much space between stringers that it's necessary to go thicker or use more epoxy, but I'm just hoping my stringers will be sufficient and like I said, it seems it was just 1/2" plywood in the boat before but the tech guy keeps reminding me that people are fatter these days and most boats now have 3/4" plywood along with mat, epoxy/bondo, then carpet. I still need to pull out my old plywood, so then I can get a look at the stringers and maybe then discuss further and decide.

Right now, I'm leaning towards just going with 5/8" plywood and one layer of CSM (or perhaps move to fiberglass?) and with maybe even a second coat of epoxy over the first that was applied with the CSM - seems to be a good compromise. I just don't want to overdo and/or overpay and potentially add too much weight to my boat in the process.

 

[Woodonglass]

Again, I will state that CSM is not recommended to use with epoxy. Yes it is compatible but...It just soaks up the resin and It offers NOTHING. The way it's made (loose strands) adds little strength to the mix. It was Made for Polyester resin and acts as a binder for it since without it the resin cures very hard and brittle and would crack and break. The CSM binds the resin together and keeps it from cracking. Epoxy on the other hand has binders IN the resin and remains flexible when fully cured and won't crack and break.Since this is an Aluminum boat, you don't need the tape or in fact any glass at all. In fact you don't even need epoxy. Epoxy, by FAR is the best sealant and protectant but, Several of the members have used the old timers recipe to seal their decks... If you keep your boat well maintained and undercover in the off season, using this recipe will protect the wood for a very long time. A few touch ups over the years will really ensure longevity.

 

[Patfromny]

I used about a one gallon kit on my 16 ft boat's wood. I did 3 coats on each side and 6 on the edges. I probably coated the equivalent of 4 sheets. Console supports, transom, floors, and some other support pieces. If you go the epoxy route I would recommend the pumps they sell. No mess and exact batches each time. Also makes you make smaller batches, or at least it made me do so. I didn't want to keep pumping them. I did only have about 8 ounces, if that, of waste. I think i used exactly one gallons worth, unfortunately the tech told me I needed the 2 gallon kit.

 

[Spooner2010]

In fact you don't even need epoxy. Epoxy, by FAR is the best sealant and protectant but, Several of the members have used the old timers recipe to seal their decks... If you keep your boat well maintained and undercover in the off season, using this recipe will protect the wood for a very long time. A few touch ups over the years will really ensure longevity.

Would this be the method to use if I was replacing the transom too?

 

[Frey0357]

Spooner:
That is the method I used for my transom. That method works great, you do have to be patient tho and get many coats on and into each of the predrilled holes in the transom (wood) core. I did about 4 coats of the above ^^^^ Mixture and then 2 coats of straight Spar. It turned out great and at only a fraction of the cost of Epoxy.

I plan to use the same mixture for my flooring also about 3 or so coats.

Frey

Here is my transom core:

 

[Woodonglass]

The Edges are the Main emphasis. The flats of plywood are very thin and then the glue keep the formula from penetrating to the inner layers. But on the edges if you allow it to soak for a long time it will penetrate deeply. The flat parts is where its important to put full strength coats of Poly. It's also important to coat any holes drilled into the wood with the formula and then coat the fasteners with a good sealant like 3M 4200. If you do this the wood Deck/Transom will last a Good Long Time.

 

[ThaRealBigBen]

Thanks for all of the input guys this is very helpful. Woodonglass, I think I will be taking your advice and not using the CSM if I still even use epoxy. However, I now have new information to provide along with a follow-up question.

Lately, I have not been keeping a cover on my boat or even storing it under a structure if that's what you meant. I used to keep it under a cover but the boat covers seem to just wear out and let water in eventually anyway and I got tired of buying new covers so I just keep it open.

With that information, would the Old Timers Method still be advisable?

Also, what are you guys' thoughts on the plywood thickness?

 

[Spooner2010]

Spooner:
That is the method I used for my transom. That method works great, you do have to be patient tho and get many coats on and into each of the predrilled holes in the transom (wood) core. I did about 4 coats of the above ^^^^ Mixture and then 2 coats of straight Spar. It turned out great and at only a fraction of the cost of Epoxy.

I plan to use the same mixture for my flooring also about 3 or so coats.

Frey

Here is my transom core:

Okay so to be clear I mix on quart of each of these 3 chemicals together and brush it on and fill the holes and edges real good? Or is it 1 quart Linseed Oil, 2 quarts mineral spirits and 1 quart Polyurethane mixed together? Also... What is "Spar"

 

[Woodonglass]

It's a 1-2-1 mix ratio. Spar Urethane is a special blend of urethane that has a HIGH UV resistance. It you plan on painting or covering the deck with carpet then you can use plain urethane. Use High Gloss since it has the most solids in the mix and is the most durable.

 

[Frey0357]

Yes, 1-2-1 ratio ^^^^^ what he said! Spar urethane is what I have pictured above in my posting, its simple and can be found in any home improvement store. You will find that the mixture is thin so many coats will ensure that it soaks in well! Also, I would not wear for favorite jeans when it comes to applying with a brush as it has a tendency to splash a bit, when applying. I chose to finish the sealing up with 2-3 (3 coats on the edges) coats of straight spar.

Good luck, and keep us posted!

Frey

 

[Spooner2010]

It's a 1-2-1 mix ratio. Spar Urethane is a special blend of urethane that has a HIGH UV resistance. It you plan on painting or covering the deck with carpet then you can use plain urethane. Use High Gloss since it has the most solids in the mix and is the most durable.

So when I'm done mixing I'll have 4 quarts total of this stuff? Sorry I'm so thick.

 

[Woodonglass]

Yes, I gallon. To do a transom and deck you'll need about that quantity. It will take about 3 days for it to dry. IF it's in good bright HOT sunshine. If it's in the garage in the shade it'll take a Week or longer before you can put the full coats of Spar Urethane on.

 

[ThaRealBigBen]

Did you guys notice my latest questions from earlier (#9)?

 

[Woodonglass]

Thanks for all of the input guys this is very helpful. Woodonglass, I think I will be taking your advice and not using the CSM if I still even use epoxy. However, I now have new information to provide along with a follow-up question.

Lately, I have not been keeping a cover on my boat or even storing it under a structure if that's what you meant. I used to keep it under a cover but the boat covers seem to just wear out and let water in eventually anyway and I got tired of buying new covers so I just keep it open.

With that information, would the Old Timers Method still be advisable?

Also, what are you guys' thoughts on the plywood thickness?

Hmmm, Not keeping a boat covered, IMHO, is really not advisable. At the very minimum I'd recommend using PVC to build a Break Down Traiangular Structure that can be set on the deck of the boat and then you can drape a Cheap Harbor Freight Tarp over it and hold it in place with Bungee Cords. I works really well and will last 2-3 years. If you don't then I would for sure use epoxy and Paint. As previously stated it IS the best most durable sealer but you pay the price. But having said this, even the epoxy will eventually deteriorate if left exposed to the elements. Here's some pics of how one member did it. It's a bit Over kill. I made mine from 1" Schedule 40 PVC for less than $40 bucks for the PVC and a $30 tarp. The tarp lasted 3yrs. That's pretty good for the Harsh Winters of Oklahoma.

As for Plywood Thickness, Most go with either 1/2" or 5/8" If you use epoxy I think the 1/2" would be fine since the epoxy would add a Lot of strength. If you go with the Old Timers the 5/8" would prolly be my choice. I am NOT a Tin Boat guy so they may have differing opinions.:noidea:

Here's another one...

http://forums.vwvortex.com/showthrea...1#post77125481

 

[ThaRealBigBen]

Okay Woodonglass, you win. I'm going with all your advice. Thanks a million!

 

[ThaRealBigBen]

Quick question (hopefully) if anybody's still listening. I got the old floor out and it seems inevitable that I'll need to change out the foam underneath. Can't I just use the pink stuff from Home Depot? I seem to recall reading about brand names and other useful info on these forums somewhere but am now having trouble finding.

 

[Patfromny]

Worked for me. Closed cell too so shouldn't ever absorb water like the foam you are about to get rid of.