Uses for high density Rigid Polyurethane foam.

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OneWayTraffic
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Uses for high density Rigid Polyurethane foam.

Post by OneWayTraffic »

So I visited a local industrial supplier/maker of closed cell polyurethane foam today. Bought a 10litre (2.5gallon) kit of standard 33kg (2lb) foam. He also had some 25mm (1") offcuts of 95kg (6lb) foam for a very cheap price. Very firm to the touch; I can't make a dent with my fingers and still light, so I picked up a couple of sheets and had him cut to 300mm by 1200mm so I could chuck it in the car. I can also get more at $30 a standard 4' by 8' sheet.

What can I use it for?

Sole?

Seats and furniture?

Place on top of expanding two part to get a flat surface under the sole, like some use a plastic sheet, but left in place.

Will it cause a hardspot if glued directly to the hull?

The boat is a C17.
Last edited by OneWayTraffic on Tue Apr 06, 2021 12:30 am, edited 1 time in total.



OneWayTraffic
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Re: Uses for high density Rigid Polyurethane foam.

Post by OneWayTraffic »

Photo. I mainly got it for flotation, but was wondering where it could do double duty.
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Last edited by OneWayTraffic on Tue Apr 06, 2021 12:39 am, edited 1 time in total.

Fuzz
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Re: Uses for high density Rigid Polyurethane foam.

Post by Fuzz »

I would do a little experimentation with a small piece. What happens when you put a little epoxy on it? How tough is it with a little glass on both sides? How is it in shear? That sort of info would be a huge help.

OneWayTraffic
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Re: Uses for high density Rigid Polyurethane foam.

Post by OneWayTraffic »

That's the plan. I understand that it's no good for foam core hulls due to the shear strength, but I was thinking I could use it to block off parts of the underfloor, tack it in place with glass and then foam around it. So there's room for limbers and enough foam to float the boat. Also wondering about seats and such. I know it's been used for surfboards.

cracked_ribs
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Re: Uses for high density Rigid Polyurethane foam.

Post by cracked_ribs »

Personally...other than bulkheads, stringers and hull, I'd use that all over the place. Cabin, seats, console, all kinds of stuff. If it isn't part of the actual hull structure I'd do a test panel, make sure you get decent peel strength with glass, and then go for it.
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

fallguy1000
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Re: Uses for high density Rigid Polyurethane foam.

Post by fallguy1000 »

cracked_ribs wrote: Tue Apr 06, 2021 1:26 am Personally...other than bulkheads, stringers and hull, I'd use that all over the place. Cabin, seats, console, all kinds of stuff. If it isn't part of the actual hull structure I'd do a test panel, make sure you get decent peel strength with glass, and then go for it.
Not to be argumentative, but peel tests are really very inconclusive. The only decent way to shear test is coupon testing. It is a been there, done it for me is all. I never opted for coupon testing. I was going to send varying degrees of resin rates and various fabrics in for coupon tests, but never did. Mostly wasn't sure the answers would have changed the direction I was going..

Peel testing on xps with a plier and 90 degree pulloff is super easy failure and hard to believe. Afterwards, one is astonished at how that crap fails so ez. But you have little of tangible quantitative value.

The pu board sounds like best use is where risk is acceptable. For me, livewell, coolers, maybe anywhere 1700 or 1708 are going and when the failure is either a) unlikely to be impacted and fail or b) doesn't matter if fails. I used xps as a livewell liner knowing it could fail and accepting if it fails; the skins will do the work. I only wanted the insulating value.
My boat build is here -------->

viewtopic.php?f=12&t=62495

OneWayTraffic
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Re: Uses for high density Rigid Polyurethane foam.

Post by OneWayTraffic »

I was thinking of a standard three point bend, but then I don't plan to use it in a way that will see any excessive bending. I do know that it's not used in marine cores, except insulation. Also used in roofing but between sheets of corrugated iron.

I was thinking of putting flotation under the gunnels and down the sides of the boat. These sheets could be glued between frames, the outside taped and glassed with a light cloth , and the inside foam filled between sheet and the side of the boat. Would stiffen up the side (not that it needs it) and provide some upright flotation.

Apparently PU of this density is a little less than 1MPA in shear. Diviny H80 is two or three times I think. Never really looked into foam core as I don't think it suitable for hulls in the size I'm building.

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Re: Uses for high density Rigid Polyurethane foam.

Post by cracked_ribs »

fallguy1000 wrote: Tue Apr 06, 2021 5:53 am
cracked_ribs wrote: Tue Apr 06, 2021 1:26 am Personally...other than bulkheads, stringers and hull, I'd use that all over the place. Cabin, seats, console, all kinds of stuff. If it isn't part of the actual hull structure I'd do a test panel, make sure you get decent peel strength with glass, and then go for it.
Not to be argumentative, but peel tests are really very inconclusive. The only decent way to shear test is coupon testing. It is a been there, done it for me is all. I never opted for coupon testing. I was going to send varying degrees of resin rates and various fabrics in for coupon tests, but never did. Mostly wasn't sure the answers would have changed the direction I was going..

Peel testing on xps with a plier and 90 degree pulloff is super easy failure and hard to believe. Afterwards, one is astonished at how that crap fails so ez. But you have little of tangible quantitative value.

The pu board sounds like best use is where risk is acceptable. For me, livewell, coolers, maybe anywhere 1700 or 1708 are going and when the failure is either a) unlikely to be impacted and fail or b) doesn't matter if fails. I used xps as a livewell liner knowing it could fail and accepting if it fails; the skins will do the work. I only wanted the insulating value.
I wouldn't be concerned about the shear, I'd be confident it's adequate for non-hull structures. I'd only be concerned with whether there was a surface contaminant that prevented me from glassing it well. If I could get a decent peel strength, I'd just go ahead and build, on the basis of my experience with a ton of different materials.
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

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