Trying a new fiberglass weave

[David Towlun]

I'm building a new canoe and I'm using a 6 oz. fiberglass cloth whose weave is new to me. It's manufactured by BGF and called Style 76281. It's a tighter weave than what I've used in the past. I've glasses the exterior and am finding it interesting to work with. It's stiffer than a plain weave but goes on clearer. I found that it took a lot more epoxy during the initial wet out, but required fewer and thinner fill coats than a plain weave. It's a bit stubborn to work with but is also twice as strong (according to BGF). I'm reserving judgment until the canoe is completed. The company I bought mine from said this about it:

"Style 76281 is a 6 oz/sq yd 4 harness satin weave fiberglass fabric that has a thread count of 44 x 32 ends/inch. 76281 uses the 9 micron filament E-Glass yarn ECG 75 1/0 in the warp and fill. 76281 is identical to 7628 in its use of yarn and thread count with the fundamental and greatly effective difference being the type of weave. The 76281 we have in stock is finished in BGF's superb aerospace silane 497A. This is a very clear finish and is good for any resin - primarily Epoxy but perfect for Polyester or Vinyl Ester as well."

Has anyone else out there used this cloth before? Any advice on working with it?

[sedges]

4 harness satin weave cloth is amazing stuff structurally. As you found in doing the outside of your canoe, it is more difficult to work with than plain weave. It is hard to get the cloth to lay flat on curved surfaces. With plain weave the weave "adjusts" to bends and curves easily, not so with satin weave. It does help to trim the selvedge to release the fibers at the edge of the cloth. This works for plain weave, too.

The inside glassing is going to be tougher than the outside with satin weave. I had so much trouble putting satin weave on the outside I didn't even try to do the inside. Actually, I think I tried and ended up peeling it off before it set up. I only did the outside on one canoe. I must say that the result was a really tough canoe. That satin weave on the outside went through a lot of abuse and only showed surface scratches.

When looking at cloth I always note the thickness. Thickness plays a big role in how much resin is going into the layup. Of course fiber density, threads/inch also plays a role.

There are lighter weight satin weaves. I think I used a 3.8 oz fabric.

If you use it on the inside, have a scissors at hand to cut darts in the top edges so it will lay flat.
For the inside you might consider dividing up the area into panels that overlap 2 inches or so. Smaller panels will conform to the curves better than a whole length piece. Another option might be to do the bottom- fairly flat- and do the bilge and sides with 4 ounce plain weave. This would put the tough fabric where you need it the most.

Let us know how it goes!

[Cruiser]

Nice to see folks trying new stuff.

I just bought some S glass for my next project and that is projected to be 40% stronger than e glass... I am curious as to the basis of the statement "but is also twice as strong (according to BGF)" as I couldn't find that on the website .... and like you I may be a bit skeptical of the claim.

However, if there is any basis, it is something worth looking at.

Curious why you wouldn't drop down to 4 oz cloth to save weight if it is that strong?

Please keep us posted as your build progresses, I am always curious and seeing other people build is a good way to learn new stuff.

Brian

[David Towlun]

Thanks for the advice, Sedges. I'm certainly nervous looking at the interior. Though I'll admit I'm more interested in paddling the canoe than a perfect fiberglass job, so that alleviates some of my anxiety. I'm weighing your advice carefully...

Brian, I'm basing the strength numbers I found on various fiberglass cloth manufacturer's website. According to BGF it's actually more than twice as strong as a similar weighted plain weave cloth from Fiberglast.

The hull will be sheathed in the aforementioned 6 oz cloth and a tight weave 3.25 oz patch on the bottom. Below the waterline is stripped with sitka spruce for additional strength. (Stripping with the spruce was NOT fun.)

I'm building it stronger for a 6 week solo trip I've got coming up in July/August. I need it to be a bit stronger to face the abuse I'm likely to give it. It's always a juggle balancing strength and weight. We'll see how this one goes...

[Jim Dodd]

One thing, I'm sure you already discovered, was the difficulty in wetting out high thread count glass.
You really have to work the resin Into the cloth ! Never try wetting two layers at a time !

For my hulls that were going to see extra abuse, I added Graphite to the last one or two fill coats, just up to about the 2" waterline. It slips over rocks much better, and I actually felt in helped slightly in the speed department. There is a draw back ! Don't store it in the hot Sun, upside down, for long. The Epoxy will bubble !

Going with a different weave on the inside is a good idea !

Great advise so far !

Good Luck !

Jim

[David Towlun]

I am all about the graphite bottomed hull. This is my sixth canoe and every one has had the treatment. Definitely worth it!