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Seeking Composite Layup Expertise

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This is a question for all you composite builders. I am strongly considering building again. Something for solo tripping/paddling that can do Cl. I-II and the occassional Class III. Probably something like a 15 ft. prospector. Maybe a Raven?

This time, however, I'd like to build a composite hull. I don't have a vacuum bag, so this would be a hand layup. But all the different fabrics and layups are making my head spin! As if Kevlar (aramid), Innegra, and carbon fiber fabrics were not enough, now they have fabrics that combine two-in-one --carbon/Kevlar, carbon/Innegra.

Given the intended use and limitations to a hand layup, what would your layup schedule look like? How many layers, in what order?
 
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I think hull shape will come into play. The rounder the bottom the more stiffness it will impart so you could get away with less cloth. Look at what Millbrook has been doing for years on their whitewater boats. Just a couple layers of s-glass and kevlar with no core as far as I know and they're pretty light. I'm guessing there are plenty of curves on those hulls to help stiffen things up.

Somewhere online Charlie Wilson gave the layup schedule for Bell's black gold layup, which was solid cloth. I wrote it down somewhere but probably can't put my finger on it. If memory serves it was somewhere around 6-7 layers on the bottom of the hull.

I think partials are important to help cut down on weight and cost. No use in the sides being as tough as the bottom.

Some fabrics are better in tension and some in compression. The tension fabrics should go on the inside and the compression fabrics on the outside. I also like the most wear resistant fabrics on the outside. If I remember right this would put kevlar or fiberglass on the outside and carbon inside.

A core of some kind would probably be fine for your usage if you don't plan on heavy whitewater usage. Foam is great but so is Jim's idea of the cedar strip core. It will be heavier but easier for some of us to source and it's something we're familiar working with.

In a hand layup I think many of the weight advantages are lost with carbon and kevlar. They're much thicker than fiberglass of the same weight and can absorb a lot of resin. Maybe it's just my technique but I've been disappointed with the weights. Maybe I've been trying to do too many layers at once but I never seem to have the patience for only one layer at a time. Multiple layers seems much easier with fiberglass.

Somewhere I read that when it comes time to squeegee the excess from kevlar that the epoxy doesn't want to come back through the cloth and that you have to push it all the way out the edge. I read that after I was doing my composite canoes but it's certainly what I experienced when doing multiple layers. I'd have a big wave of epoxy ahead of the squeegee that would all push out when I reached the edge of the cloth. It was very slow, very messy, required a lot of pressure. I kept going over it and I kept getting more out. At the time I think I was doing 3 layers (2 kevlar and a carbon on top) and the upper layer of carbon ended up being starved after all this squeegeeing even though I suspect there was still excess resin in the kevlar.

I don't have any experience with innegra and basalt. I don't expect them to be wonder cloths compared to carbon and kevlar and don't think it probably makes a lot of difference in a canoe. What would make me most inclined to use them instead of carbon or kevlar (especially kevlar) would be handling characteristics. I'd gladly trade kevlar for a cloth that gave me similar structural attributes but was easier to cut, wetout, and sand.

Alan
 
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I too tried two layers at once. It didn't work for me either. I was glassing in the Winter in a heated shop, But I put more of the blame on the tightness of the weave.

I'm a firm believer in one at a time.

My last one Black Pearl, was a solo at 16'1", with a 1/8" insert, in the football., flotation chambers , and wood trim. 36#.

I was happy with the weight.

There are several threads here, a search should help you find more info.

here is one. I liked.

https://www.canoetripping.net/forums...tandem-tripper
 
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I did two layers of carbon at once, I would not do that again, but not for the reason you may think.
my layup was, from outside to inside, 2 layers of 6 ox E-glass, 2 layers of 5.5 oz carbon, 1/8” thick Divinycell H80 in the football only, and a single layer of 5.5 oz carbon scraps over the foam.
All trim is H80 foam under 13.? Oz carbon bias weave tape/sleeve.
My carbon copy Kite is incredibly stiff.(14’6” OAL)
At 29 lbs, I am not happy with the weight. Most of the overweight I believe is due to the carbon trim and massive amounts of resin needed to wet it out.
Wet out of the two at once carbon was difficult to see when it was fully saturated.

IN my not so humble opinion, expensive exotic materials are not required for a tough boat, only glass and a full foam core.
 
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How would one go about doing a full foam core in a hand layup?

This is not strictly conjecture...a few years back I did a few numbers based on some sample sections (back when I still had access to all sorts of lab equipment) that I had performed load deflection tests on. Theory is the guide, empirical data is (or should be) proof of the theory. Composites are very difficult to fully characterize without full testing.

Double layer of 6 oz E-glass on the outside, 1/4" H80 bottom transitioning to 1/8" H80 sides, double layer of 4 oz E-glass on the inside. Yes, full foam core. All hand laminated, squeegeed but not peel plied (plyed?)
Gunnels (gunwales, gunwhales) thwarts and seat pedestals double layer glass over foam, painted to look like carbon.

If you do the calculations, it's much more beneficial (from a strength perspective) to add section rather than layers, and whatever section should be as low of a density as practical. Again, I must admit that this is my fully biased opinion.

Modern production boats are made of many layers of assorted materials, not necessarily chosen by design purpose alone. The production guys have all sorts of constraints, from material costs to marketing demands. A backyard builder hopefully has unlimited freedom, within the laws of physics.

As a side note, I had many years of R&D design experience, often interfacing with major national and international entities, corporate, government and military. Often the best suited designs were not utilized to due various factors such as cost, cultural reluctance (we've ALWAYS done it that way), political pressure, marketing constraints...the list goes on.
My point is, freed from the constraints of those that limit the production guys, why not build your hull to be the best possible for your desired use? There's no need to follow traditional build convention...

Now down to the nitty gritty. How to do a full foam core hull?
OK....I'm a bit torn. H80 can be heat formed to conform to complex curves. Heat mold as large a section as possible over a male pattern? Strip build with foam strips? Build inside out, with a glass shell over a plug that then has added foam and inner layers? I haven't got that far yet. I'm still finishing my new house and need a few more months before I can dive into my own full composite build. If I had the time and money I would build heated male-female molds to form a full H80 foam core all at once, or at least a half hull at a time.
Nah, probably strip foam build over forms, then glass inside and out like any stripper.

I'm anxious to hear what others would do.
 
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SG, I had dreams of doing up a foam core, just using strips and building on a mold. To make this sort of radical departure there needs to be a driving goal ( IMO ) and in this case it would be a quest to lower the weight, while maintaining the hull strength. I looked up the cutting blades and H80 sources and then started running numbers.

For this work, I pulled the hull weights, glass weights etc for this comparison, from my last 2 lighter builds... granted this is just "ball parking " the numbers, but they seem to align and should likely be a good estimate.

The 15 foot hulll using 3/16" weighed in at 12.76 pounds, yielding .85 pounds per foot
The 16 foot hull using 1/4" weighed in at 18.6 pounds, yielding 1.16 pounds per foot
The 3/16" hull is ~73% the weight of the 1/4", which is about what should be expected from the thinner strips

Based solely on weight, using 5 pound/cubic foam would yield a 1/4" hull weighing roughly .25 pounds per foot or 4 pounds for 16', giving a weight reduction of 18.6 - 4 = 14.6 pounds

So the weight reduction value is ~14 - 15 pounds for a 16' solo ... using a 1/4" foam core, i think this is a reasonable estimate for planning purposes.

Now this setup will require more layers of glass to give additional stiffness lost by the core material, the initial 6 oz layer is common for both and most regular strippers ... my layers typically weigh in the region of .72 - .76 pounds per foot for 6 oz cloth with (3 epoxy coats exterior, 2 coats interior), ~11.5 pounds for a 16' solo

Assuming a 16' solo, a second layer of 6 oz glass, the weight reduction becomes 14.6 - 11.5 = 3.1 pounds and for 4 oz that would be ~14.6 - 9 = 5.6 pounds

I suspect the 6 oz is a safer layup and if I got adventuresome and tried the 6/4 layup, I would do 4+6 ... given inside surface is stretching force and outside is compression force and FG is not good in compression, it will do you more good to have more glass on the inside.

Dropping the strip thickness 3/16" reduces the advantage of foam by 2 pounds to ~ 3 - 4 pounds and 1/8" will drop that even further ... with the additional effort/expense in trying the foam, my evaluations all screamed that working with the wood strips might be the cost effective solution here.

I realize that some of these numbers are estimates and not carved in stone, but I think they are a realistic look at what may be achievable with foam versus wood.

Just a bit musing with the numbers


Brian
 
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Great research Brian !

That confirmed my suspicions, on foam verse wood, in the weight ratios.

There are several unanswered questions, for me in the stiffness ratios between foam and wood. Also Bonding between materials. I can verify the bonding between wood and Building foam ? Wood is much much better. In fact DON'T use Pink Building foam, if you plan on things holding together !

Building wood strip, and using 1/4" thick strips, with 6 oz E-glass inside and out on a tandem. is minimum.
I've noted several builds that exhibited Oil Canning. Adding an additional outside layer of 6 oz E-glass to the lay up . solved the oil canning. This is real life experience.

To me ? going to 3/16" thick strips would definitely require the additional 6 oz E-glass layer. not only on a tandem, but I would also do on a good sized solo.

I'm looking forward to seeing more composite builds, as I truly believe that is our future ! Research can save us all from becoming Guinea Pigs !

Western Red Cedar is is going trough the roof as prices soar on all wood ! Finding clear, flat grained WRC ? Good Luck.

Thanks !

Jim
 
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Jim, 3/16" strips may surprise you .... my last build used them with 6 oz glass on a 15 footer. It's been into the piney woods twice and is solid, no give on the football at all.

I am planning another build with them this winter ... pushing out to 16'6" with 4 oz S glass if I can find a way to get some.


Brian
 
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Seems to me most of the hand lay ups of composite canoes have more layers than most manufactures use. For example, in the 150 or so Merrimacks I helped build in getting them up and running again we basically used 3 layers of the different fabrics totalling 16-18 oz. Currently I'm finishing up a prototype for them that has no gel coat and only 2 layers.
Merrimacks are all hand layups using female molds and no vaccum bagging.
 
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Jim, 3/16" strips may surprise you .... my last build used them with 6 oz glass on a 15 footer. It's been into the piney woods twice and is solid, no give on the football at all.

I am planning another build with them this winter ... pushing out to 16'6" with 4 oz S glass if I can find a way to get some.


Brian

Sweets ? Maybe they can't ship across the Border ?

So it's really not about the weight of the cloth, but the resin it takes to fill the weave,

Admittedly I use too much resin in mine, as I like a smooth interior. If you could get Peel Ply, to follow the contours of a hull ? You could easily skip a fill coat.
 
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[QUOTE

I am planning another build with them this winter ... pushing out to 16'6" with 4 oz S glass if I can find a way to get some.


Brian[/QUOTE]

Brian, I bought my s-glass from Composites Canada - they have 4 ounce at around $11/yard ($Can), but only in a 30 inch width on a cut yard basis. You would have to buy a full roll of 125 yards to get 60 inch width (I asked if they could sell me 60 width by cut yards but no dice). I’m using the 4 ounce for the football only on my languishing tandem build, over a 6 ounce s-glass layer on the exterior (which they have at 60 inch width for almost $30/yard (ouch). I guess you could overlap two sides of the 4 ounce at the keel to get full coverage?

I found them generally very good to deal with, BTW - good communication and prompt shipping.

Tony
 
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Seems to me most of the hand lay ups of composite canoes have more layers than most manufactures use. For example, in the 150 or so Merrimacks I helped build in getting them up and running again we basically used 3 layers of the different fabrics totalling 16-18 oz. Currently I'm finishing up a prototype for them that has no gel coat and only 2 layers.
Merrimacks are all hand layups using female molds and no vaccum bagging.

Wow ! You are using wood ribs aren't you ?

Vinyl Ester ?
 
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Wow ! You are using wood ribs aren't you ?

Vinyl Ester ?

Jim,

The ribs are wood but they are 1/16" veneer so not at all the structure on a traditional wood canvas and maybe no more than your strip inserts. I will add there is a fiberglass mat football on the floor.

Yes, we used vinyl ester although now they use some of the newer poly resin.
 
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[QUOTE

I am planning another build with them this winter ... pushing out to 16'6" with 4 oz S glass if I can find a way to get some.


Brian

Brian, I bought my s-glass from Composites Canada - they have 4 ounce at around $11/yard ($Can), but only in a 30 inch width on a cut yard basis. You would have to buy a full roll of 125 yards to get 60 inch width (I asked if they could sell me 60 width by cut yards but no dice). I’m using the 4 ounce for the football only on my languishing tandem build, over a 6 ounce s-glass layer on the exterior (which they have at 60 inch width for almost $30/yard (ouch). I guess you could overlap two sides of the 4 ounce at the keel to get full coverage?

I found them generally very good to deal with, BTW - good communication and prompt shipping.

Tony[/QUOTE]

Thanks Tony,

I did find them, but I am not in a hurry to get the 30" stuff and was going to call on the 60", you saved me a call for that ..... Noahs said they were going to start stocking S glass, but in 6 0z flavour, which again doesn't do me much good.

I may call Canada Composites and ask about 4 ox 60" by the yard, maybe if they see ppl want it that way, they may start offering it, otherwise, i may be making a road trip, if the border ever opens.

Brian
 
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Yeah, I spent a fair bit of time last fall looking for a Canadian source for s-glass (as I am sure you have too). Composites Canada and Aircraft Spruce (5.8 ounce only) were the only ones I could find. Did not push hard when I asked CC about 4 ounce-60” as I didn’t really need it for my build, but don’t see why they wouldn’t want to sell cut yards if it moves more product for them - worth a shot I think. While I don’t have plans yet for another build after the current one, after looking at the beauties that you have put together I’d be happy to spring for a portion of a full roll if I could get you to build the canoe for me ;-)
 
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Sweets ? Maybe they can't ship across the Border ?

So it's really not about the weight of the cloth, but the resin it takes to fill the weave,

Admittedly I use too much resin in mine, as I like a smooth interior. If you could get Peel Ply, to follow the contours of a hull ? You could easily skip a fill coat.


The 6 oz cloth is generally classed at 8 mil and 4 oz at 6 mil .... so the final layer is going to be on the order of 25% thinner ... I figure that will translate directly as weight. Given I have the weights for how I apply FG and resin, i can figure how much weight savings I can expect to see.

I suspect though that the thinner glass won't be as stiff, even though it is stronger, so the plan is to do the outside as a single layer (4oz), do the inside (4oz) and add an extra piece to the football (4oz) if I need more stiffness. The real plan is to add the football unless I am really surprised with the single layer. I think this will give comparable or better strength as the 6 oz and still save a few pounds.


Brian
 
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Yeah, I spent a fair bit of time last fall looking for a Canadian source for s-glass (as I am sure you have too). Composites Canada and Aircraft Spruce (5.8 ounce only) were the only ones I could find. Did not push hard when I asked CC about 4 ounce-60” as I didn’t really need it for my build, but don’t see why they wouldn’t want to sell cut yards if it moves more product for them - worth a shot I think. While I don’t have plans yet for another build after the current one, after looking at the beauties that you have put together I’d be happy to spring for a portion of a full roll if I could get you to build the canoe for me ;-)

Maybe we could collaborate on a build, I don't think we are that far apart in Ontario .... I will advise what CC says.
 
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Brian, I bought my s-glass from Composites Canada - they have 4 ounce at around $11/yard ($Can), but only in a 30 inch width on a cut yard basis. You would have to buy a full roll of 125 yards to get 60 inch width (I asked if they could sell me 60 width by cut yards but no dice). I’m using the 4 ounce for the football only on my languishing tandem build, over a 6 ounce s-glass layer on the exterior (which they have at 60 inch width for almost $30/yard (ouch). I guess you could overlap two sides of the 4 ounce at the keel to get full coverage?

I found them generally very good to deal with, BTW - good communication and prompt shipping.

Tony

Thanks Tony,

I did find them, but I am not in a hurry to get the 30" stuff and was going to call on the 60", you saved me a call for that ..... Noahs said they were going to start stocking S glass, but in 6 0z flavour, which again doesn't do me much good.

I may call Canada Composites and ask about 4 ox 60" by the yard, maybe if they see ppl want it that way, they may start offering it, otherwise, i may be making a road trip, if the border ever opens.

Brian[/QUOTE]

Have you ever tried using 30" and overlapping at the keel? In my experience and opinion doing half at a time is a lot easier to work with and get a good solid hull.
 
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