Anyone create FRP Board and Polystyrene sandwich for decking.

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thill

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As far as adhering the foam to the FRP, I wonder if there aren't less expensive adhesives that will work well. Something like PL Premium panel adhesive, if you mist with water to kick it off. a 1/16x1/8" notched trowel should give you good, even coverage and a great bond. The polyurethane adhesives are tenaciously strong, but they are skyrocketing in price too.

Interesting stuff. I have FRP and pink and blue board around. I may have to play around with some of it. You got me thinking!
 

fwman1

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Thanks fellas.

Yes, the gorilla glue type adhesives might just do the trick. The hard thing with them is keeping things flat during cure, as they exert a huge amount of pressure as they kick off. I guess they have that tamed already if it is designed to use on paneling.

I don't think the epoxy would be prohibitively expensive as much as I just overbought on the volume. Three ounces per square foot (both sides) means that around 3 quarts would have done a full 4x8 panel. I'm basically doing a bit less than a 4x4 area, so could have bought smaller. Since they don't evaporate when curing, they do add a bit of weight to the finished panel.

I ordered the aluminum channel to form the structure for the front deck today. I won't be able to do much on it till next weekend though.
 

-CN-

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Interesting take on using foam board for decking. I've thought of using FRP as well, but it is expensive. You've revealed in your research there that by the time you build a 4x8 sheet of decking in this fashion you are over $100 per sheet. And that's not even your finished surface. What are you going to put over it? I learned that the foam board over an already existing solid structure will work fine on its own - the weight savings of foregoing the FRP in areas like this is astronimical, as foam weighs nearly nothing on its own. I like your idea for any places that require structure. A little less expensive than marine plywood, and a little bit lighter. I've outlined my use of foam board almost exclusively in other posts on here.
 

fwman1

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I made some good progress on the front deck. The outline of the aluminum framework is completed as well as trimming the pink foam board to fit. Unfortunately, the weather is turning very cold so I won't be able to make up the sandwich composite till it warms up some. My epoxy hardener was chosen for 50 degree temps. I don't think it will much care for twenties and thirties. I am ready in case we get an unpredicted warm day or two.

Once the composite is cured, my plan is to lay out 2x4s on edge modeled after the deck support I built today. Then I'll put the the completed and cured decking on top and walk/jump on it to see what amount of center and cross support is needed. I'll add that structure to the boat.

After that, I'll install the composite deck then reinstall my electronics and trolling motor. I'm open to suggestions on what to use to cover the FRP. How about this?
Nautolex Sisal Pattern Marine Vinyl Flooring - 74" - Cool
 

Stand Up

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I made some good progress on the front deck. The outline of the aluminum framework is completed as well as trimming the pink foam board to fit. Unfortunately, the weather is turning very cold so I won't be able to make up the sandwich composite till it warms up some. My epoxy hardener was chosen for 50 degree temps. I don't think it will much care for twenties and thirties. I am ready in case we get an unpredicted warm day or two.

Once the composite is cured, my plan is to lay out 2x4s on edge modeled after the deck support I built today. Then I'll put the the completed and cured decking on top and walk/jump on it to see what amount of center and cross support is needed. I'll add that structure to the boat.

After that, I'll install the composite deck then reinstall my electronics and trolling motor. I'm open to suggestions on what to use to cover the FRP. How about this?
Nautolex Sisal Pattern Marine Vinyl Flooring - 74" - Cool
That looks like it will work really well. I like that it is made for marine use. This build is going to be so nice when you're done. I can hardly wait to see the finished product. Good job my man.
 

thill

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Looking forward to seeing pictures and hearing the report of your results. At $100/sheet, that is a very viable option, if it stays together and doesn't delaminate after time.

I just had a friend buy a boat that is wood-free, and he was excited, but ALL of his floors have delaminated, the foam separating from the FG skins. It's a real mess. I currently have a Horizion pontoon boat with the exact same problem. This winter, I'm going to pull the rails, console and all the furniture, and see what can be done. In the end, it will probably all get ripped out and replaced, but we will see.

So your work could be very helpful to others, if it is successful. Thanks for posting.
 

fwman1

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A couple of processes to complete before mixing the epoxy. First, I made a disposable tool to cover the foam surfaces with small holes. This should help give the epoxy some teeth, seeing as the sheer strength of the foam/epoxy bond is probably the weakest part of the composite. The second prep is to scuff the inside of the FRP board to remove any bonding agents. I used a 3" steel wire bit for this. I'll wipe the FPR down with Alcohol before mixing and applying the epoxy. I have several sheets of OSB board to place on composite board while the epoxy is curing.

I have a section of my interior shop ready to assemble the composite board (heated room). I'll tackle the epoxy part tomorrow.
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fwman1

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Finally got to work on this today. I used a 4" metal cutoff disc in a grinder to trim the edges of the glued sheets. I then used 80 grit belt sander to finish the edges. I'll put a final coat of epoxy on these sanded edges before final installation.

TEST! Supported only on 3 sides. I can stand in the middle and hop up and down and it is solid as a rock.
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I will add some center bracing just because it doesn't weigh much, but I think it is actually overkill.
 

fwman1

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I forgot to add, the panel weighs 20.1.lbs
It is about 12 square feet.

I mixed 36 ounces of epoxy for each side lamination. A total of 72 ounces for this deck. There was some extra in each batch, and some that oozed out the laminations.

I spread a coat on the foam, then spread a coat on the FRP board. Once I put the FRP board on the foam, I tried to push out as much of the excess as possible. I wanted to ensure that I had a wet joint throughout.

Tomorrow I'm working on the center and side supports. I'll be rewiring my boat for the new setup of casting deck,
new trolling motor, and new fishfinder. Hopefully I'll get it on the water to test out before too long.
 
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eeshaw

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.6 lb. per square foot isn't bad for weight. What is the cost per square foot roughly?
 

fwman1

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Price a 4x4 finished piece.
One 4x8 FRP $41.00
One 4x4 pink foam $10.00.
Epoxy 72 ounces $55.00.
$106.00 for 16 square feet = $6.62/ft sq.
Weight is 1.6 pounds per square foot.

A fair amount of labor. Worth it to me, as my Jon will have a maintenance free casting deck, but will not have gained a significant amount of weight.
 
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SaminMass

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Impressive work. You might want to post a photo of the cross section so that you have a record. I’ll be curious to see how it holds up.
 

eeshaw

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Glad it worked out for your application. Too bad it won't work for mine. I've been looking for a suitable replacement or substitution for ACP. I need something that's cost effective, UV resistant, paintable and malleable. I tried out a 4x8 ACP that has a smooth surface that could be painted or have a wrap placed on it (really expensive!). The biggest problem is the availability and cost, 200.00+ for one 3mm x 4ft. x 8ft. sheet. For some reason companies that supply sign companies won't sell to the general public, at least that's been my experience so far.
 

Vol423

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There is an outfit that makes a product called ACRE. It is rice hulls mixed with a resin of some sort. You can use as is or paint it or glass it. I used the product once to replace a plywood floor in a big boat. I painted it and glued down a vinyl floor to it. The boat was sold but the owner tells me it works fine.
 

fwman1

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LOL, I wish I'd known about this ACRE board. It weighs about the same as my laminate and costs under $150 for a 1/2" 4'x8' sheet. It would be nice to know what weight it would support. Still, thanks for adding that to the thread. Good info.
 

fwman1

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Well, a lot of time has passed, but I am nearing completion of the Jon boat overhaul. New removable lights, new trolling motor and front mount, new casting deck and center section decking and Hydro-Turf deck covering. I'll be covering the bench seats with it as well. I am adding a pedestal stool mounted B-100 seat that I can move around, or remove as needed.
Hopefully I'll have some shots on the water soon.
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