How to lay the fiberglass?

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Francis
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How to lay the fiberglass?

Post by Francis » Mon Jan 14, 2019 2:33 pm

My racing canoe is completely stripped and sanded, so it's time for the fiberglassing. I've ordered 4 oz S-glass Aerlite, De widest fabric you can find here in Europe is 77 cm (30 inch), so not wide enough to cover the complete hull in 1 time. I have 2 options in mind: I center the fabric in middle of the canoe for the full length, do the epoxy work and then I add full length strokes for the ises. I never worked before with 4 oz, so I have no idea if I'm gonna see the transition between the strokes.
Or, I lay the fabric from gunnel to gunnel, and overlap it for 5 cm, but then I have 7 seams.
I'm also a little bit worry about the feathering of the fabric with all these overlaps.
What is your advice?

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Cruiser
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Re: How to lay the fiberglass?

Post by Cruiser » Tue Jan 15, 2019 8:48 am

I think if I were to do this, I would probably break the operation into 2 steps. Applying cloth to do one side and 0verlap the center line by 4"-6" ....allowing this to cure to almost hard (hard enough to feather). Then feather the entire length and smooth sand where the secong cloth overlap will fall, then cleanup and do the other side.

This would give you a feathered overlap down the center line which shouldn't show, at the same time the overlap will add quite a bit of strength down the center line.


Brian

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Jim Dodd
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Re: How to lay the fiberglass?

Post by Jim Dodd » Tue Jan 15, 2019 9:28 pm

Cruiser is Spot on ! I'd do exactly the same.

We may differ in application tools ! So a suggestion. Many will recommend a Squeege. They are good to have around ! But I'd have a Good Cigar foam roller handy, for wetout, as well as fill coating !

Good luck !

Jim
Keep your paddle wet and your seat dry!

Francis
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Joined: Tue Sep 16, 2014 3:03 pm

Re: How to lay the fiberglass?

Post by Francis » Wed Jan 16, 2019 2:17 pm

Thanks! So, an overlap at the keelline looks the best solution. Some say to lay both cloth (with an overlap) on the hull and wet them at the same time.
I can follow the advice of Cruiser, but I read in a lot of posts that wet in wet gives a stronger bond, so maybe first I do a test to see what works best.

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Cruiser
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Re: How to lay the fiberglass?

Post by Cruiser » Thu Jan 17, 2019 8:41 am

I have made that post myself Francis .... so I concur.

A short response is not always as clear and procedural as it could be ...

First, read your epoxy manufacturers suggested recoat times, they are not all the same ..... I would do the following

- apply 1/2 of FG with the keel overlap
- allow to set (not cure) to the "green" stage (finger nail leaves an impression, but is no longer tacky)
- do a quick feather of the overlap edge ... if you leave it raw, you will get a "ridge" when the next layer is applied. There is a time in the curing process where you can scrape the edge and still be in the recoat time frame .... this allows you to get that edge feathered, do the other half and still get a chemical bond between the coats. If you can't pull this off due to whatever constraints, it is not the end of existence as we know it, you can sand it a bit and create a physical bond, which is still strong, just extra work and not quite as strong (which of course means we all try and hit that window because we are a bit anal, why else would we be building our own boats , lol)
- now apply the other half with the overlap .... you can choose to add this coat over the original area as well ... you have to watch and figure out application, because this means one half has a 2 coats and the new side on has 1 .... the advantage is if you keep going you can get all coats on without any more sanding, just finish up with 1 seal coat to the second FG side to balance out the application
- next day (or some time soonish), feather that exposed edge, do a good sanding job to level the epoxy coat all over the boat
- vacuum, wipe down and generally get the sanded coat clean, apply a thin coat of epoxy over the whole hull, this will seal the feathered edges and give a nice, smooth finish
- go over the hull with your finish sand paper, you already "smoothed" the hull, this sanding is just to take off the gloss

Feathering the 2 edges of the overlap like suggested should make that area look completely flat with no hint it overlaps.

Any questions, I am sure we can answer them

Good luck

Brian

Francis
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Re: How to lay the fiberglass?

Post by Francis » Thu Jan 17, 2019 1:38 pm

Thank you Brian, for the manual you've writed down :-)
I didn't know you can sand the first layer epoxy (the complete hull) without touching the glass. Sounds risky but you have the experience, so I follow your advice.
Maybe in the same line of my previous question: when laying the bias strips? My idea was first the main cloth and then the bias strips (3 pieces). The first one 3" wide (stem), second 5" wide (stem to knuckle) and third 7" wide from knuckle to the area with the most impact. Makes that sense?

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Cruiser
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Re: How to lay the fiberglass?

Post by Cruiser » Thu Jan 17, 2019 4:11 pm

Hi Francis,

Technically, what I was suggesting is that you complete all 3 epoxy coats, then once that cures .... do the regular sanding, to get the epoxy ready for varnish .... you shouldn't really varnish that one feathered edge as it has exposed FG, so clean the hull and put a final thin coat of epoxy to seal everything up, then do a light resand of the hull to take the gloss off .... most of this is to deal with the 2 feathered edges for the overlap.

Normally, you would put on the FG, do 3 timed coats and let cure ... then go sand fare.

As far as bias strips go ( I am assuming these are for the Bow/stern re inforcement/abrasion) .. this is a link to my last build. It is a ways down the post, there are pics and descriptions that may help.


viewtopic.php?f=3&t=2006&start=75

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Jim Dodd
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Re: How to lay the fiberglass?

Post by Jim Dodd » Thu Jan 17, 2019 8:51 pm

SCRAPE ! Don't sand uncured epoxy ! (allow at least 7 days to cure epoxy before sanding)
I Scrape with a carbide scraper, to Feather the joint, the next day, but sooner is quite doable !

Bias strips over the stems, put the widest strip on first ! They to can be feathered within a day easily with a scraper !

Scraping leaves no dust impregnated into the epoxy, sanding can, if not properly cleaned !
Good Luck Francis !

Jim
Keep your paddle wet and your seat dry!

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Cruiser
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Re: How to lay the fiberglass?

Post by Cruiser » Thu Jan 17, 2019 9:05 pm

I think that is my line Jim .... scrape don't sand epoxy ....

but you do have a point, I made a slight error in the order of operation. Once the 3 coats are on, the edge can be feathered the next day, but you should wait till the epoxy is cured as Jim said, before you sand down the hull ... sanding uncured epoxy = BAD .... and use a respirator ANY time you are sanding epoxy.

Francis
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Joined: Tue Sep 16, 2014 3:03 pm

Re: How to lay the fiberglass?

Post by Francis » Fri Jan 18, 2019 12:20 pm

With all this info, I think/hope I can do a nice job! Thanks a lot!

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Jim Dodd
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Re: How to lay the fiberglass?

Post by Jim Dodd » Fri Jan 18, 2019 8:45 pm

You will !
You are looking Before leap ! That's a good sign !

Jim
Keep your paddle wet and your seat dry!

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