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PostPosted: October 27th, 2006, 10:59 am 
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Joined: July 18th, 2001, 7:00 pm
Posts: 189
Location: Mounds View, Minnesota US
Yes, dreaming over the data is interesting. I down loaded data from both Hexcel and BGF for the weaves "offered" and put them on a spead sheet so I could compare and play.

While both companies offer lots of the same patterns, they both also offer patterns that the other doesn't.

Also, the strength data must be either taken or calulated differently by each company, as the BGF strength values are much lower then the Hexcel values. I try to only use them for comparison, usually sticking to Hexcel data.

The 3733 vs 7533, these are 5.80 and 5.85 oz cloths, and are very similar, they are both 18x18 but
3733 is a ECG 37-1/0 by ECG 37-1/0
7533 is a ECG 75-1/2 by ECG 75-1/2

The 18x18 is the "gross" pattern, the ECG 37-1/0 is the bundle and strand pattern.

The ECG is the fiber used, E glass, C mean coated (I think), G (I think) is a 9 micron fiber, the 37-1/0 and 37-1/2 describes the strand and bundle configuration, off-hand I don't remember the details of what these numbers represent. But there is about the same amount of glass in each pattern, confirmed by the very close weights/yd, but it is boundled and groups slightly different, the 37 is half of the 75, but the bundle is 1/0 vs 1/2 (this isn't "one" and "one half", it's a combination of strands and/or bundles 1 by 0 and 1 by 2), again I don't remember the exact "code" but you get the idea.

As for E vs S glass, yes, the fibers are about 20% stronger, but there are so many other things that effect the overall strength of a given cloth that (I believe) the weave configuration is more important then the fiber material type.

For example the fine fibers, the D and E's end up having a higher strength / weight/size then the G's. And weave patterns that have fewer "over and unders" (twills) are stringer then plain patterns.

And yes, the fine weaves with smaller fibers does take more effort to wet out, as it's 1) harder to get the air out, and 2) they move around very easy, that's why I use a brush, a roller just moves them around too much, at least for me.

The weaves I used conformed to the hull OK, and yes they were coated, I believe all the cloths have to be coated to facilitate the resin bond. There are a number of different coatings or finishes and you have to get the correct one for the resin you are using. With that said, with epoxy now so common, finishes compatable with epoxy are probably the norm now.

I did use 2 layers of the 2.85 oz, both in and out, I also used 2 layers of the 2.3 oz in the football, again, both in and out. To get the strength, the 2.3 was layed with the "long side" or warp, running across the canoe.

I bought the cloth from a outfit called Thayercraft. I seems to be a 1 man shop who buys excess and left overs (my assumption) and sells them real cheap BUT only in full rolls. (and he sells small amounts on ebay).
I bought 2 complete rolls, 232 yds for about $230 plus about $50 for shipping, or about $1.2 yd, delivered. And they were in unopened, sealed factory boxes, nice stuff. i places the oder by phone and a CC, I had the glass in a few days and wasn't charged for a month. I figure I would have spend about $200 or a bit more if i got just want I needed from other suppliers, so for about $50-80, I got an addional 4 times the glass.

http://www.thayercraft.com/

Dan


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PostPosted: November 2nd, 2006, 12:50 am 
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Joined: October 10th, 2006, 3:10 pm
Posts: 25
Location: Vancouver
Dan, I've looked at a few plans and it seems like it is common for a canoe to have a circumference of over 50" at it's widest point. Was this the case when you used the 3oz cloths mentioned above? If so, how did you go about covering the hull? The lighter weight cloths appear to come in 50" wide rolls.

One option that appears to be doable is to use 1678 (3.2oz) from a 44" wide roll. Maybe I could overlap this cloth along the bottom of the canoe and have a single layer up along the sides of the hull?

One last question that maybe you can answer. Given two different cloths with different weights but same breaking strength, can one say if using the lighter cloth would result in a more "delicate" boat? The lighter cloth would be less resistant to abrasion because of thinner fiberglass thickness and corresponding thinner epoxy thickness. So I can guess that compression or tension failure would be the same, abrasion resistance would be less for the thinner cloth, and stiffness...? All I can guess is that the lighter cloth would have less epoxy and therefore maybe a bit less stiff. Any thoughts on this?

thanks


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PostPosted: November 6th, 2006, 1:19 pm 
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Joined: July 18th, 2001, 7:00 pm
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Location: Mounds View, Minnesota US
Doug,

Sorry for the delay just back for the weekend.

I checked my sheet and my max cir length was 56 inches, the 2.85 oz I got must have been 60" wide, as I layed it on like normal and had just a bit to cut off.

The 2.3 I layed "crosswise" so the width didn't matter much, it was just how many seams there were. I think the stuff I got this time was 54", as it was just shorter then the 2.85, which might be enough for most designs. When I did the 2ed canoe, that 2.3 was also layed like normal with excess to cut off, that was a Winisk, off hand I don't know what it's cir length was.

I know folks often use narrower glass and make a seam someplace, I've never done it though. I think John W has related he's put the seam down the middle, with a bit of overlap to get 2 layers in the middle. I know a guy making a kevlar canoe that did what you describe and he wasn't happy with the "step" just below the gunwales.

As for the durability, I think I've heard arguments both ways, and I don't have any personal experience as to which might be better, ie, more, thicker resin or more thinner glass. (My canoes only have a few flat water trips on them.)
I've often though about adding a layer of poly-something on the outside for toughness, but haven't tried it yet.

Stiffness, I don't know how much comes from the glass and how much from the resin. I'd prefer more glass myself. I would think adding extra resin would be a poor way to make a canoe stiff.

Dan


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PostPosted: November 6th, 2006, 1:31 pm 
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Dan Lindberg wrote:
Doug,

The 2.3 I layed "crosswise" so the width didn't matter much, it was just how many seams there were. I think the stuff I got this time was 54", as it was just shorter then the 2.85, which might be enough for most designs. When I did the 2ed canoe, that 2.3 was also layed like normal with excess to cut off, that was a Winisk, off hand I don't know what it's cir length was.

Stiffness, I don't know how much comes from the glass and how much from the resin. I'd prefer more glass myself. I would think adding extra resin would be a poor way to make a canoe stiff.

Dan




On the crosswise layer. Did you butt the factory edges together to make the seams or overlap or overlap and doublecut the seam? I assume the crosswise layer was under the lengthwise?

Everything I have read about laminate is that the glass gives the strength. The resin is the matrix to make the glass solid and hold it in place. More resin doesn't add much strength and adds a lot of weight.

The ideal is just enough resin to wet out and then fill the weave. Not too little, not too much.

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...........O
......(___|/____)
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PostPosted: November 6th, 2006, 4:44 pm 
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Location: Mounds View, Minnesota US
Hi Jose,

Yes, your description of the glass/resin load sharing is what I've also heard, and basically believe, though I have to also believe that a layer of resin over the glass has to help protect it. But sense I want it to weight as little as I can, I try to minimize the resin on the outside fill coats.

As for how I layed the glass, I cut off the factory sewn edges, and overlaped the pieces by about 4-6 inches. In my experience, the factory sewn edge results in a larger "raised" line then the fabric without the edge.

And yes, both layers of the 2.3 oz layed crosswise are under the 2 layers of 2.85 layed lengthwise. The 2 layers of 2.3 are also "staggered" lengthwise, to reduce the transition/step.

Dan

"On the crosswise layer. Did you butt the factory edges together to make the seams or overlap or overlap and doublecut the seam? I assume the crosswise layer was under the lengthwise?"


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PostPosted: November 6th, 2006, 4:52 pm 
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Dan Lindberg wrote:
Hi Jose,

As for how I layed the glass, I cut off the factory sewn edges, and overlaped the pieces by about 4-6 inches. In my experience, the factory sewn edge results in a larger "raised" line then the fabric without the edge.


So the 4-6" transverse overlaps became "ribs" of a sort?

How do you keep the edges from fraying and making a mess?

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Solo canoes and single blades, with a sail for those windy days...

...........O
......(___|/____)
.........../


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PostPosted: November 7th, 2006, 2:36 pm 
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Location: Mounds View, Minnesota US
Ribs, yes, of a sort, not very thick though. :)

Yes, they do fray some, but with the light glass, you have to go slow applying the resin anyway. (It takes me about 4-6 hours to wet out a full double layer of thin glass.)

Then try covering the edges with plastic and smooth the surface out with either your hand or a scraper. After the resin is cured, the plastic just pulls right off, leaving a smooth surface.

I tried using peel ply for this but got starvation in the glass, so I went to the plastic.

Dan


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PostPosted: November 7th, 2006, 3:32 pm 
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I've done the plastic trick before. I'm amazed how one coat of resin, over 6 oz material will come out smooth, w/out fill coats.

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Solo canoes and single blades, with a sail for those windy days...

...........O
......(___|/____)
.........../


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PostPosted: November 7th, 2006, 6:00 pm 
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Location: Grand Marais, MN
Dan, what kind of plastic are you using? Saran Wrap?


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PostPosted: November 8th, 2006, 10:48 am 
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Joined: July 18th, 2001, 7:00 pm
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Location: Mounds View, Minnesota US
Bryan,

I just use regular clear poly that the home centers sell.
I don't buy it special for canoe work, just use what's laying around.

And I reuse it, I cut a pile of strips of different widths, and just grab one when it's needed. When pulled off, it's put back in the pile.

Dan


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 Post subject: saran
PostPosted: November 8th, 2006, 10:59 am 
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I have had instances when saran wrap stuck to the epoxy and I had to sand it out. I use 2 mil and higher plastic. Painters drop cloths, lightweight visqueen. I even used plastic bags from Walmart once but the printing telegraphed onto the epoxy!

there was a guy who built a plexiglass bottomed boat. He glass and epoxied the panels prior to assembly, useing a heavier mylar on the wet out coat. After peeling the panels were mirror smooth.

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Solo canoes and single blades, with a sail for those windy days...

...........O
......(___|/____)
.........../


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PostPosted: November 8th, 2006, 11:59 pm 
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Joined: October 10th, 2006, 3:10 pm
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Location: Vancouver
Do you guys squeegee the wetout prior to putting on the plastic? I think you'd have to... so you wet out the cloth, squeegee, place some plastic down, smooth it out and let the epoxy cure. voila.

I've built a Pygmy s&g kayak. They have you butt ply panels together by wetting out some glass with epoxy then placing mylar on top of the glass, then putting weight on top of the mylar. The difference with this is that Pygmy doesn't get you to squeege the wetout, they're expecting epoxy to squish out a bit I think.


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PostPosted: November 9th, 2006, 12:26 pm 
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Joined: July 18th, 2001, 7:00 pm
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Location: Mounds View, Minnesota US
Doug,

I don't/haven't squeegeed my wetouts.
I try to put on just enough resin and not have to remove any, this is partly (I think) why it takes me so long to wet out. I have to go a lot slower, because of waiting for the cloth to soak up the resin before either adding more or moving on to the next area. I do weigh the resin as it's mixed/applied, and keep in mind how much I should be using total, to get an idea if I have to spred it farther or not.

Also, the light cloth moves around very easy, especially the top layer when weting 2 layers together.

Dan


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