double layer fiberglass techniques

[sluggo]

Hello all,

I think I will be using some narrower fiberglass for the Freedom 15. This means that I will use two lengths of cloth for the hull, and they will overlap down the middle. When doing the overlap how is the epoxy applied?
1. do one side, then lay down the other side of fiberglass and apply epoxy to 2nd side
2. do one side, let cure until not tacky and then lay down the other side of fiberglass and apply epoxy
3. lay down the cloth at the same time and apply epoxy on to two layers at once

#3 would probably be the lightest layup buy maybe tricky to do
#2 is probably the easiest but maybe uses significantly more epoxy
#1 might be pretty hard to lay down the 2nd layer

Any thoughts or opinions?
thanks

[RonMc1954]

IMHO I vote for #3 I have but 2 layers on the bottom of all my boats and the only problem I had was I had to be more patient with the wetout. It takes a little longer for the epoxy to soak in. Also make sure your epoxy is warm 70F to 80F
Ron

[sluggo]

thanks Ron,

I'm not sure what I'm going to do about the epoxy. I'll be ready in a couple of weeks but we're heading for the deep freeze of winter. I can get my garage to maybe 15C, and of course I can warm up the epoxy as well. I've fiberglassed in these conditions before and it was okay. The dual layer adds another level of complexity.

cheers

[RonMc1954]

It's just that the warmer the epoxy the easier it will soak the fiberglass. I have put epoxy in a bucket of warm water for a while to raisethe temp.
Good Luck
Ron

[Rick]

#1 and #2 might cause warping in the hull, if the cure happens on one side before the other... I had this happen when glassing a thin piece of wood on one side only, the epoxy expanded when it cured and warped the wood.

[Rod Tait]

May I ask why you are using two pieces when one piece of 60 in 6 oz should cover it in one piece?

[pawistik]

..... I'll be ready in a couple of weeks but we're heading for the deep freeze of winter. I can get my garage to maybe 15C, and of course I can warm up the epoxy as well. ....

Put some light bulbs or a heat lamp under the hull for some time (a couple of hours?)before glassing. That will warm the surface and help keep the viscosity of the epoxy low so it wets out better & quicker. The surface temp needs to be uniform before you start or air coming out of the pores of the wood will form bubbles in the epoxy. You could just turn off the warming lights when you start applying the epoxy then the gas in the wood pores will contract and pull the epoxy in.

I underestimated the effect of warming wood and the length of time for it to become stabilized and had a lot of bubbles forming when I glassed the inside of the hull. The inside was worse than the outside because on the inside the expanding gasses had nowhere else to go but into the freshly applied epoxy. I also wonder if heat given off by the curing epoxy (exothermic reaction) was a contributing factor?

Cheers,
Bryan

[sluggo]

May I ask why you are using two pieces when one piece of 60 in 6 oz should cover it in one piece?

I was thinking about using some very inexpensive but strong 4oz (actually 3.2oz) cloth: Style 1678 from http://www.thayercraft.com/Style%201678.htm Actually I was speaking to a client of your yours about a year ago about this cloth and he ended up buying it and I was going to buy some from him. I don't know if he's used any yet. For me it's kind of an experiment, I don't know how clear it will wet out. for me it's not a huge concern because I am thinking about painting the canoe white anyways. Heck if I know if there will be any real upside to using it other than saving a few bucks and a few pounds. I'll probably be kicking myself and swearing while overlapping the cloth trying to get it to wet out clear.

[Larry in Champaign]

I ordered a samle of this 1678 cloth. I wetout at 60 F. using U.S. Composited 635 (thin) resin and 2:1 (slow) hardener. I offset three layers of cloth to see how 1,2,and 3 layers wetout. The cloth wetted quickly and I squeeged heavily. Half of the layup got a second (filler) coat the next day. Follow the link for a closeup view.

https://netfiles.uiuc.edu/lwest/www/167 ... iq=-zd25gz

I'll be using this cloth on my next canoe (just finished milling strips today).

Larry

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[Glen Smith]

Those test results look very encouraging! I should ask them (Thayer Craft) if they ship to Canada.

[Glen Smith]

Well, I checked with Thayercraft and they do not currently ship to Canada. Too bad, they have some really interesting prices.