Wood or Foam/Formica? It’s time to decide!

[Matt Johnson]

I still suggest checking out Eurolite marine plywood from World Panel. The weight savings and smooth face surfaces make it a great option in your application.

Matt

Originally Posted by Chotu

At this point, all signs are pointing to wood.

Problem with the Formica finishes are weight.

Formica/core panel
4x8 Formica Sheet: 11lbs x2 faces = 22lbs
4x8 Core (foam or honeycomb@5lb/cuff density) = 6.5lbs
Some Glue/contact cement for this panel weighs the same as some paint for the wood do they cancel out.
Total weight 4x8 panel installed - 28.5lbs


Marine ply panel
1/4” 4x8 okoume marine ply = 18lbs
16’ of 1x2 furring strip for sticks as needed = 4lbs
Paint weighs same as contact cement for Formica so cancels out.

Total weight 4x8 panel installed -max 22lbs

[s/v Jedi]

Originally Posted by Chotu

At this point, all signs are pointing to wood.

Problem with the Formica finishes are weight.

Formica/core panel
4x8 Formica Sheet: 11lbs x2 faces = 22lbs
4x8 Core (foam or honeycomb@5lb/cuff density) = 6.5lbs
Some Glue/contact cement for this panel weighs the same as some paint for the wood do they cancel out.
Total weight 4x8 panel installed - 28.5lbs


Marine ply panel
1/4” 4x8 okoume marine ply = 18lbs
16’ of 1x2 furring strip for sticks as needed = 4lbs
Paint weighs same as contact cement for Formica so cancels out.

Total weight 4x8 panel installed -max 22lbs


Considering I have to make the Formica panels and replace core in many areas with wood anyway for hinges, etc, the plywood should go up faster even if finish work of painting and/or polyester is involved.

I agree that marine plywood is the best option. Next step is finishing which, starting with choice of primer, immediately brings the “no epoxy” up again... I think that epoxy primer may not be a problem because the “converter” does not smell/feel like epoxy hardener to me.

[Chotu]

Originally Posted by s/v Jedi

I agree that marine plywood is the best option. Next step is finishing which, starting with choice of primer, immediately brings the “no epoxy” up again... I think that epoxy primer may not be a problem because the “converter” does not smell/feel like epoxy hardener to me.

If it uses an amine hardener, it’s out.

It’s the hardener that’s the killer for me. I can handle the BPA side of things.

But how about some non epoxy alternatives? Next best things?

Polyester encapsulated wood has been sitting in a damp, closed up boat through daily cycles of awful humidity and high heat in Florida since February. I think checking out how it did will help a lot with this part.

I mean think of plexus adhesive. Perfectly good replacement for epoxy adhesive.

Now, what’s the paint primer equivalent specially made for priming wood in damp humid and hot environments? That’s one of the questions to figure out.


Also, I’m definitely going to need to run my generator all day long if I go with the plywood. I have to keep the moisture down to keep weight off and to keep coatings happy.

[s/v Jedi]

Originally Posted by Chotu

If it uses an amine hardener, it’s out.

It’s the hardener that’s the killer for me. I can handle the BPA side of things.

But how about some non epoxy alternatives? Next best things?

Polyester encapsulated wood has been sitting in a damp, closed up boat through daily cycles of awful humidity and high heat in Florida since February. I think checking out how it did will help a lot with this part.

I mean think of plexus adhesive. Perfectly good replacement for epoxy adhesive.

Now, what’s the paint primer equivalent specially made for priming wood in damp humid and hot environments? That’s one of the questions to figure out.


Also, I’m definitely going to need to run my generator all day long if I go with the plywood. I have to keep the moisture down to keep weight off and to keep coatings happy.

Epoxy primer doesn’t use “hardener”... they call it “converter”. It also has a 15 minute induction time and long pot life so I really think it’s different.

Fur surfaces out of sight you can use whatever keeps moisture out, like polyester resin, but for the painted surfaces you see every day, you need fine finishing and to get that water resistant, nothing beats epoxy primer. I think you’ll be okay because I can’t believe anyone would use amine based products for painting.

[rslifkin]

There are also one part "epoxy" paints like the Totalboat bilge paint. I wonder how those work chemically?

[Chotu]

Originally Posted by s/v Jedi

Epoxy primer doesn’t use “hardener”... they call it “converter”. It also has a 15 minute induction time and long pot life so I really think it’s different.

Fur surfaces out of sight you can use whatever keeps moisture out, like polyester resin, but for the painted surfaces you see every day, you need fine finishing and to get that water resistant, nothing beats epoxy primer. I think you’ll be okay because I can’t believe anyone would use amine based products for painting.

Unfortunately, awlgrip 545, which is the primer on the exterior of my boat does contain the dreaded ingredients:


https://specialtycoatings.brand.akzo...20190715_1.pdf

[Chotu]

Originally Posted by rslifkin

There are also one part "epoxy" paints like the Totalboat bilge paint. I wonder how those work chemically?

http://www.totalboat.com/wp-content/...r-Base-SDS.pdf


Also contains unspecified epoxy components.

The risk here is drying like a kid who can’t be near peanuts can die. So, need to find alternative products.

[smj]

When we started the finish on the inside of our cat we considered encapsulating all the plywood in epoxy, and then I thought why?
It’s a lot of extra time, money and ads some weight, and how many boats have you seen that had there interior plywood encapsulated? Worst I’ve seen is some veneer peeling of perfectly good ply or damage from ply sitting in the bilge uncovered.
I think a good paint job should do a decent job of sealing the plywood against moisture, but maybe be extra careful about sealing the end grain.
We painted the plywood walls in our shower on our old Cherokee cat with 2 part and never had any problem.
Not that encapsulating would be a bad thing, but to me maybe going to an extreme.

[rslifkin]

I agree that encapsulating is likely overkill for cabinets. For a shower, yes, I'd do it. But for cabinets, even if they get wet once or twice over the years, unless there's a bunch of water going right into the end grain, it's unlikely to be an issue. All of the marine plywood cabinets, floors, etc. on my boat are not fully encapsulated (often covered with veneer or vinyl on one side and painted on the other) and they're doing just fine after after almost 35 years. In any spots where I've had stuff apart while working on things, the wood looks basically new.

[Chotu]

And to support SMJ and Rslifkin’s views on encapsulation:

I unintentionally left a few scraps of the original 1/2” Okoume Marine plywood I used on parts of the boat outdoors in Florida for the past 5 or 6 years. Completely unfinished with no protection.

The one in the moist, not too sunny spot turned all black on the faces. I just sanded that mold off and used it for an unimportant part on my boat last year. No physical degradation. Looked perfectly new after sanding off the mold

The one sitting in a pool of water each time it’s rained in south Florida over the past 5-6 years (countless times) got all black too, but did get crumbly. It had to have spent 1/3 of its time underwater or sitting in a puddle

The one sitting out in the rain that was then dried by the sun each day after the rains turned a very bleached out silver color, like teak left to go natural. No physical degradation. I sanded off the fluffy silver bit on the outmost ply and it went right back to perfectly new looking.

This is the wood I was planning to use, but in 1/4”

[rslifkin]

Based on those results, you should be in good shape. For the most part, wood is a pretty darn durable material as long as it's not continuously wet.

[Chotu]

Originally Posted by smj

When we started the finish on the inside of our cat we considered encapsulating all the plywood in epoxy, and then I thought why?
It’s a lot of extra time, money and ads some weight, and how many boats have you seen that had there interior plywood encapsulated? Worst I’ve seen is some veneer peeling of perfectly good ply or damage from ply sitting in the bilge uncovered.
I think a good paint job should do a decent job of sealing the plywood against moisture, but maybe be extra careful about sealing the end grain.
We painted the plywood walls in our shower on our old Cherokee cat with 2 part and never had any problem.
Not that encapsulating would be a bad thing, but to me maybe going to an extreme.

And maybe if I put that effort into improving air flow through the boat to amazing levels, it’ll always be dry anyway.

And truthfully, none of my production boats from the 1980’s has ever had any encapsulated plywood. It’s always been marine ply with a teak veneer. Or teak itself, but that’s a special case of course.

[Chotu]

Originally Posted by rslifkin

Based on those results, you should be in good shape. For the most part, wood is a pretty darn durable material as long as it's not continuously wet.

Cool! Makes me feel a lot better.

I get so worried I’m going to choose the wrong path. It’s really stressful.

[smj]

Originally Posted by Chotu

Cool! Makes me feel a lot better.



I get so worried I’m going to choose the wrong path. It’s really stressful.

I think the best thing is to choose what you are comfortable working with.

[Chotu]

Originally Posted by smj

I think the best thing is to choose what you are comfortable working with.

That would be plastics, fiberglass and epoxy. Synthetic materials. Wood is extremely difficult for me, but I thi I learned enough reading and reading to pull it off. Ha ha