Been looking at some of the foam core builds here and was wondering if anyone has done one using the blue, green or pink XPS foam you can buy at any home improvement store? It is completely compatible with Epoxy. There are some tricks to working with it but it would seem to me to be useful for one of these builds.
XPS Foam For Foam Core Builds
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SurfDuffer
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SHUG, take it from the guy that did your lam schedule... use what I told ya and don’t deviate!
And for God’s sake, don’t anybody try to build a foam cored powered vessel from XPS or EPS foam!!! Damn it, why is it so hard to understand that XPS and EPS are an insulation not a structural product. Look at sheer/peel/moe/friability/melt point/density/etc... and it is clear that the structural grade marine and aerospace foams are what should be used. The reason different densities, thicknesses, strength foams are used in many production boats simply comes down to $ aka best bang for the buck. And in the case of lightweight and high performance vessels it comes down to engineering the lightest yet strongest vessel for a given weight. I.O.Ws, use the righy core in the right spot to achieve the designs goals and strength needs.
I'm going to try and be a completely objective asshole here. There has been a new wonder core just like there is a new slice free driver every year since the dawn of time. Neither is promising, but with proper fundamentals things can be achieved. Know your materials and their limitations and expect their pluses and minuses.
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10,845 Posts
What is really going on here?
You are the only person who is saying it can be a viable product and everyone else says otherwise (including an entire industry).
Are you a shill for an insulation company?
If not, when will you build it?
You seem to have it all figured out - get on with it.
You are the only person who is saying it can be a viable product and everyone else says otherwise (including an entire industry).
Are you a shill for an insulation company?
If not, when will you build it?
You seem to have it all figured out - get on with it.
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77 Posts
At the end of the day, the foam just provides the spacer between two skins. The strength is in the skins not the foam. The only real exception would be the transom where you are hanging your motor. If your skins and your foam are in the correct proportion to the loads they will experience there is no problem. That is the essence of composites. Its intriguing to read the posts from people who insist things can't be done or must be done their way and the conviction with which they insist.
I just want to check. We are talking microskiffs here.......not offshore battlewagons smashing through inlets. Just want to make sure we are on the same page here........casue I'm thinking 14 foot one or two man 20hp microskiff on calm protected waters.
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I just want to check. We are talking microskiffs here.......not offshore battlewagons smashing through inlets. Just want to make sure we are on the same page here........casue I'm thinking 14 foot one or two man 20hp microskiff on calm protected waters.
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7,566 Posts
This is wrong, completely. The definition of a composite is made up of various parts or elements. Meaning they need to work together. The core/foam is not just a spacer between the skins, it becomes a structural member helping to support the whole. Like I said, I've done test layups with xps, I'm not just talking here. Could you make the skins thick enough so the foam core doesn't matter, yes, it's called making a mold. At which point it's better to remove the foam completely after the layup, so it's no longer a core element. Using foam as a form or mold is NOT composite building by definition because it is not working to help each other.
Yes we are talking lightweight skiffs here, which makes the coring more important then your "battlewagons". In an offshore boat you need thick glass to support the amount of distortion that can occure from the pressures exerted. A 1/2" thick skin of glass is not just 4x stronger then 1/8", the strength grows exponentially as the thickness increases. Heavy weight is an advantage offshore, but a major disadvantage in the shallows. If both hulls were running the same smooth waters then the glass could be thinner, but you need to account for the distortion that occurs when running on plane to the hull bottom. Your XPS foam and no peel strength and low frangibility. This means the distortion over time will make it fail and crumble. There have been many builders over the years who tried inferior products and the results showed. Rippled skins, seperate skins, cracks in the glass from lack of support.....
You are trying to equate skiffs to surfboards and I get it. A surfboard has so little pressure on the bottom that you can use just the foam with no skin. Any of us who remember spring break in cocoa beach or Lauderdale, remember that was the thing to do for visitors. They would buy Styrofoam surfboards or boogieboards, use them for the weekend and then toss them in the dumpster. Will they last, nope, that's why a good board costs so much, but they did function. You couldn't do that on a skiff, the amount of pressure per square inch increases dramatically with speed even over smooth waters. Thin fiberglass skins need proper and durable backing to deal with this. Thicker skins do not, but at that point you no longer have a lightweight skiff so what was the point?
I get it, look through my builds and you will see I have tried to reinvent the wheel from time to time. In most cases it seems a wheel rolls best when in the tried and true round shape. You have guys here advising you that have built boats personally, and professionally, using various composites. If you don't believe us then go do some test samples and see for yourself like some of us have. I'll predict your results based on my own. You will find out that using an inferior core means thicker glass, your boat will end up heavier and more expensive then if you spent the money on a proper core.
Ok, I’ve had enough! I will personally grab a sheet of 3/4XPS foam and do a side x side using carbon core 5lb pe foam “most economical core foam available” and do some flex/peel/MOE/and the good old fashioned BFH tests provided the XPS makes it past the flex test! Will laminate both sides with 1@1808 0/90 & 1 @1708 45/45 resin will be epoxy! Maybe I too can save a small fortune on my personal stuff since I would never dream of endangering a client’s life or his/her loved ones using F’ing insulation for a structural core in a vessel that takes much more abuse than the so called battle wagons! Wash board ripples create a harmonic effect that will straight up destroy boats over time if they are not engineered and built properly! Stay tuned!😉
PS, stop arguing about it! Many of us have tried alternatives and all samples have failed miserably, PERIOD! PS, you are arguing with some actual professionals in the industry also so perhaps you should take their advise and pull your head from your dark spot for just a second! And surfboards ain’t skiffs and while they take a pounding, the forces generated are not comparable to what a skiff sees! Apples/oranges my friend! Carry on and build it if you want, I’d like to see it!
PS, stop arguing about it! Many of us have tried alternatives and all samples have failed miserably, PERIOD! PS, you are arguing with some actual professionals in the industry also so perhaps you should take their advise and pull your head from your dark spot for just a second! And surfboards ain’t skiffs and while they take a pounding, the forces generated are not comparable to what a skiff sees! Apples/oranges my friend! Carry on and build it if you want, I’d like to see it!
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10,845 Posts
JC,
Don't waste the money. The guy has not even generated a single question based on the info given to him. He has only continued on with his schilling.
This thread will die and he will never build a boat made from insulation. He won't like our answer's and will start trolling other sites until 2022 and his progress on his build will be exactly where it is right now. NOWHERE!
I'm done. You and FC should just check out too. Complete waste of time and energy.
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77 Posts
Do me a favor and score both faces of the XPS foam with a wallpaper roller. Do a stress test to see what it breaks at when fully cured. Cheers.
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77 Posts
Schilling? The funny thing is, my opening post simply asked if anyone here had attempted it. Rather than just say no or just ignoring the thread because you didn't have anything to add we had people chiming in with opinions and some of these people I'm not 100% convinced even know what XPS is then we had others who want to lecture or mock. I'm glad you're done. You didn't have anything to add to begin with. Cheers.
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7,566 Posts
Yep think I'm done too. I waited for you to post up any actual data backing up your outlandish assumptions, but no go. Go for it sport, post up the whole process, including your tests. Proof is in the pudding. If you have the courage of conviction you'll start in short order so we can see.
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9,132 Posts
Just saw 👀 a commercial on flex paste. Just spread out over some wire screen and you have a skiff suitable for a small tiller. Who knew
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77 Posts
Can't wait for those test panels.
This thread is about as worthless as the guy wanting to build a diesel inboard on panga then saying he was going to change his plans to two inboards or something dumb for a project that was never going to happen. Surfduffer has provided no real world examples of this working besides surf boards. I can’t wait for the build thread to start.
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77 Posts
Here is the original thread topic. Please read closely:
"Been looking at some of the foam core builds here and was wondering if anyone has done one using the blue, green or pink XPS foam you can buy at any home improvement store? It is completely compatible with Epoxy. There are some tricks to working with it but it would seem to me to be useful for one of these builds."
So to sum things up. Nobody here has tried it.
"Been looking at some of the foam core builds here and was wondering if anyone has done one using the blue, green or pink XPS foam you can buy at any home improvement store? It is completely compatible with Epoxy. There are some tricks to working with it but it would seem to me to be useful for one of these builds."
So to sum things up. Nobody here has tried it.
Are you intentionally being obtuse? you asked the question, then 3 peoples answers that it is not suitable for skiff building then you come back with this,
You then get called on the FACT it is not anywhere even close to structurally sound to use as a boat core and you just keep spouting off. If your so sure it is safe to use then buck up buttercup and build a skiff out of it and prove the actual experts giving you advise wrong.
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77 Posts
If you use XPS you will die. LOL.
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2,648 Posts
Just wanted to revisit this. Did you end up doing anything? What were the results?
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