Bias Cloth

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David Towlun
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Joined: Wed Jul 05, 2017 6:37 pm

Bias Cloth

Post by David Towlun »

Hello-

This is my first post, though I am writing about my third canoe. As I'm already finished with the boat, there's nothing I can do but file away your advice for my next one (yes, I need 4 canoes for some reason). I built a 15'-4" solo canoe (not a Bear Mtn. design...sorry) using 3/16" thick strips and a 3.25 oz tight weave cloth and was able to get the craft down to 32#. To add additional strength to the bottom of the hull I added the ubiquitous football patch on the outside and inside of the hull. However, the football patches were cut on the bias. I assumed that having two layers of differing weave directions would add strength to the hull. I've paddled it and it seems pretty sturdy, but I also haven't hit a hidden rock yet.

How far off am I? Has anyone tried this?

Eager to hear your responses. Thank you.

David
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Cruiser
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Location: Bowmanville, Ontario

Re: Bias Cloth

Post by Cruiser »

Hi David,

I will be starting #4 in the next month or so, so that seems very reasonable lol

My understanding of applying cloth on the bias versus aligned, is that the bias is far better at conforming to curves (more flexible)... but is not quite as strong as when applied with the weave aligned.

I am not sure if you would ever notice the difference in your application, I use cloth on the bias for the stems, for additional abrasion resistance.

Brian
David Towlun
Posts: 9
Joined: Wed Jul 05, 2017 6:37 pm

Re: Bias Cloth

Post by David Towlun »

True, but my real question is, will two sheets of cloth of differing weave direction work to stiffen a craft? Much like the alternating layers in plywood. Obviously warp and weft run perpendicular to each other, so turning a sheet 90° won't help, but what about a sheet set at 45°?

My wife learned about future #4 when she saw the rebuilt canoe rack in the garage. "Honey, nice canoe rack. Is that space for a fourth canoe?" Guilty by omission...

D
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Jim Dodd
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Location: Iowa

Re: Bias Cloth

Post by Jim Dodd »

First off Welcome to the site David !
What designs have you built ? Sounds like a good layup plan !

The reason behind laying cloth on the bias, as I was taught, is not only to make it conform better, but also to add strength. Whether it actually adds strength, is hard to tell.
I've laid my cloth on the bias on every canoe I've built.

Differing weaves, may be more visible, but I don't believe there is a problem as to strength or bonding.

S-glass is more visible than E-glass, but it's stiffness, and abrasion resistance, makes up for it's slightly visible weave pattern.

I'm a real believer in double layering cloth on the outside. Mostly for the abrasion resistance, and the added stiffness.

Love to see some pics of your work !

Jim
Keep your paddle wet and your seat dry!
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Cruiser
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Re: Bias Cloth

Post by Cruiser »

Hi David,

Sometimes posting can get a little imprecise .... 2 layers will always be better than 1 layer. Jim points out that he always goes bias on the second layer to reinforce the bottoms and this likely also creates strength in different directions than 2 aligned layers.

This link says:

http://www.fibreglast.com/product/the-f ... ing_Center

"Woven Fabrics

Woven fabrics are strong reinforcements because the fibers are bundled into yarns oriented in just two directions. The warp and fill yarns run at 0 and 90 degrees respectively. Thus, fabrics are anisotropic, or strong in only two directions. Fabrics need to be oriented so the fiber yarns run parallel to the expected loads. If extra strength is needed in a different direction, another ply must be added at an angle to the first. The most common angles are +/- 45 degrees."

I read this to mean that it won't double the strength, but create a more robust composite that can better handle loads (or impacts) from differing directions (than a single layer or multiple aligned layers).

Canoe composites have to deal many differing loads, so having that multiple weave direction is a real asset to the overall strength of the composite.


Brian
David Towlun
Posts: 9
Joined: Wed Jul 05, 2017 6:37 pm

Re: Bias Cloth

Post by David Towlun »

Jim & Brian-

Thank you for the info. I had never used fabric on the bias on the hull and had only used narrow strips of it on the stems before, so I'm glad to have my intuition held up by facts. I appreciate your time.

I've attached a photo of the new canoe. It's a Newfound design I had been looking at for a while. I'm taking it on a two week solo trip to the Temagami region in August. My first trip into Canadian waters!

Thanks.
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Cruiser
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Re: Bias Cloth

Post by Cruiser »

Beautiful area, I am sure that you will enjoy the area .... but be warned, prepare for blackflies and mosquitos ... this time of year is about peak for them and they can be vicious if you are not prepared.


Brian
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Patricks Dad
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Re: Bias Cloth

Post by Patricks Dad »

Black flies should be done by mid-August. Mosquitos could be lighter too by then (depending on weather). That's one of my favorite times to paddle (later is better).
Randy Pfeifer
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Re: Bias Cloth

Post by Cruiser »

I misread, thought it was sooner, btw ... if you google Algonquin park and bug report, you can see how the bugs are doing in that area. However, the blackflies can be persistent in that area.

It should be about the same as Teg.

Brian
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Jim Dodd
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Re: Bias Cloth

Post by Jim Dodd »

Nice Kootenay design David ! Those stems give it away. They are a little more of a challenge to build ! Nice workmanship !
Bruce Kunz designed a Kootenay solo, that is very well received in the lake country of Northern Minnesota.
Image
A good friend had one built for him. He's an Outdoor Photographer, with his gear and small dog, has done several 2+ week solo trips. I've paddled it empty, and it handled great !
Thanks for sharing !

Back to bias cloth, I lay all my cloth layers on at least a slight bias, when I can. Obviously wider cloth makes it more evident.
Using 50" width cloth on a solo, doesn't allow much bias.

Have fun on your solo trip ! I'm planning an October BWCA trip, can't wait !

Jim
Last edited by Jim Dodd on Fri Jul 07, 2017 9:40 am, edited 1 time in total.
Keep your paddle wet and your seat dry!
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Jim Dodd
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Location: Iowa

Re: Bias Cloth

Post by Jim Dodd »

After looking over your canoe David, I noticed you have a coating on the bottom of your canoe. Graphite ?

I've done this on a few, and like how it handles the rocks !

Jim
Keep your paddle wet and your seat dry!
David Towlun
Posts: 9
Joined: Wed Jul 05, 2017 6:37 pm

Re: Bias Cloth

Post by David Towlun »

It is graphite. Wouldn't build a boat without it. I like wooden canoes, but I work them hard out on the trail. The graphite makes everything slide much easier. I paddled my father-in-law's canoe once and put a scratch in the hull - no graphite. Learned two lessons that day...!

D
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