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Old Jul 09, 2011, 12:00 PM
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Joined Feb 2010
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Question
fiberglassing cloths

I'm about to start the process of fiberglassing my wooden boat's hull. I got 5 oz and 2 oz cloths.
Is there a standard oz cloth to use or can you use any oz size?
my boat size is 32" long 12" wide if that helps any.
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Old Jul 09, 2011, 12:05 PM
Veni, Vidi, Feci
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Motor City
Joined Dec 2004
12,573 Posts
I've used single and double layers of 2 oz on hulls that size with good success. I've even covered a boat in 1/2 oz, where I wanted to avoid weight.

If you have a sound wood hull, you only need a thin layer of f/g to waterproof it and to keep the plank seams from opening... you're not trying to build a freestanding glass hull with a wood liner.
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Old Jul 09, 2011, 03:52 PM
ADM. 48TH FLEET
oxnard ca.
Joined Jul 2007
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pat is right.....when i glass a plug before making a mold i use 2 oz. cloth

joe
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Old Jul 10, 2011, 07:05 PM
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USA, IL, Morton
Joined Feb 2007
339 Posts
Fiberglassing wood hulls

I have built several wood and corrugated paper hulls, and I use 3/4 oz. cloth, I use Bondo fiberglass resin to hold the cloth to the hull. You must have your hull faired to a good quality to keep from sanding through the microballoons. This can get frustrating to keep the the fiberglass from wrinkling and where you want it. I have used Elmers Spray adhesive to hold the fiberglass, to position it on the hull, the big boys say it won't work but I have done it. After that is dry I use two coats of Microballons and resin. Microballons and resin must be worked in a well ventilated place, this is bad stuff. Everyone has a different method to use fiberglass. I use mine to make things water resistant and stong and to make a very smooth surface to paint. Automotive sandable primer can be used along with Bondo filler, even auto spot putty. Remember the final result as with painting, the original surface must be finished to a good standard. I fiberglass my decks and some structures to get good surfaces and a wood fiberglassed deck installed in a fiberglass hull will weld itself to the hull if you scuff up and clean the fiberglass hull. The USCG Cutter I am building has a fiberglassed wood hull and weighs 1 1/2 pounds, with driives, deck and structures.. I hope I haven't bored you. Always try anything new on scrap pieces. Thank You Stu Kerrn
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Old Jul 11, 2011, 04:05 PM
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United States, MI, Macomb
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Sounds like a Trojan hull! I have to agree with Pat. You just want a thin layer to keep your wood from separating or warping. You want to keep sharp edges from chipping and waterproof the hull. I would also recommend .56 ounce so the fabric won't bleed through the paint. If you spent a lot of time fairing your hull and making it true, the last thing you want is a dull fabric finish.

I like to coat everything with West System, but it's not always the best idea unless you know how to use the "tipping" method with a foam brush. West System will sag with nasty drips and build up in corners if you put it on too thick. You will spend countless hours wet sanding and eventuallly burn through on thin spots. I've never used anything else, so I had to develope my own methods. Zpoxy might be the way to go.
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Old Jul 12, 2011, 09:02 AM
Stilwell Shipyard
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United States, FL, Cape Coral
Joined Nov 2003
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I like 2 oz. fiberglass and I apply it with Minwax Polycrylic. I like the polycrylic because it can be cleaned up with water (before it dries). I also use a spray glue to hold the glass in position. Some spray glues can eat foam so test first. It will warp thin balsa, I had no problem using it on my all wood Dumas barges.
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Old Jul 12, 2011, 02:03 PM
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USA, IL, Morton
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Dull Fabric finish

Quote:
Originally Posted by Tollytime View Post
Sounds like a Trojan hull! I have to agree with Pat. You just want a thin layer to keep your wood from separating or warping. You want to keep sharp edges from chipping and waterproof the hull. I would also recommend .56 ounce so the fabric won't bleed through the paint. If you spent a lot of time fairing your hull and making it true, the last thing you want is a dull fabric finish.

I like to coat everything with West System, but it's not always the best idea unless you know how to use the "tipping" method with a foam brush. West System will sag with nasty drips and build up in corners if you put it on too thick. You will spend countless hours wet sanding and eventuallly burn through on thin spots. I've never used anything else, so I had to develope my own methods. Zpoxy might be the way to go.
These aren't dull fabric finishes,fiberglassed decks and fittings, there are many before and after photos, here are two examples, the Crane barge has a paper hull, all structuers fiberglassed both are scratch built. How many pretty work boats do you see on brown water. Everyone has their own way of finishing, do what works for you. My way forgives errors and looks like it is shrunk fit to the hull and structures. Thanks Stu Kerrn
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Old Jul 12, 2011, 03:09 PM
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Thanks all for the advice. I,m going to do the hull with 5oz and the top with the 2oz. I know doing the hull with 5oz will make the boat abit heavy but It's a yacht not a speed boat. I figure 2 coats of res, sand, then 1 sponge coat should do it with some color pigment on the last coat. I want to try it out to see if I don't need to paint it.
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Old Jul 12, 2011, 03:17 PM
Stilwell Shipyard
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United States, FL, Cape Coral
Joined Nov 2003
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zrhino - That is a very aggressive plan. Keep us updated... for better or worse.
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Old Jul 12, 2011, 09:08 PM
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Stu Kerrn's Avatar
USA, IL, Morton
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Sounds like a plan

Quote:
Originally Posted by zrhino View Post
Thanks all for the advice. I,m going to do the hull with 5oz and the top with the 2oz. I know doing the hull with 5oz will make the boat abit heavy but It's a yacht not a speed boat. I figure 2 coats of res, sand, then 1 sponge coat should do it with some color pigment on the last coat. I want to try it out to see if I don't need to paint it.
Sounds like a plan, Lot Of Luck, please post a few photos. Thank You Stu Kerrn
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Old Jul 13, 2011, 11:06 AM
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United States, MI, Macomb
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Quote:
Originally Posted by zrhino View Post
Thanks all for the advice. I,m going to do the hull with 5oz and the top with the 2oz. I know doing the hull with 5oz will make the boat abit heavy but It's a yacht not a speed boat. I figure 2 coats of res, sand, then 1 sponge coat should do it with some color pigment on the last coat. I want to try it out to see if I don't need to paint it.
You'll find 5oz to be very thick and not very cooperative on angles and corners. Are you using a plain weave or a Crowfoot? I have some experince with fiberglass in boats this size. Your crisp edged chines will now have a radius contour, unless that's what you want. I use 5oz cloth on the exterior hulls when I want to get that Florida "custom built" look for work boats. Trust me, 5oz is an overkill.
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Old Jul 13, 2011, 09:52 PM
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Stu Kerrn's Avatar
USA, IL, Morton
Joined Feb 2007
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More FiberGlass

Quote:
Originally Posted by Tollytime View Post
You'll find 5oz to be very thick and not very cooperative on angles and corners. Are you using a plain weave or a Crowfoot? I have some experince with fiberglass in boats this size. Your crisp edged chines will now have a radius contour, unless that's what you want. I use 5oz cloth on the exterior hulls when I want to get that Florida "custom built" look for work boats. Trust me, 5oz is an overkill.
I have three photos of 3/4 oz. cloth and microballoons, on these hulls form your opinion. You have to develop your own method, I have only used 3/4 oz. cloth for the same reason some people use airbrushes they don't hide details, 3/4 oz. cloth fits everything like a glove and you must have a hull finished to a high standard, the fiberglass hides little. It is strong, like I said before, I use this method to cover corrugated paper. Thanks Stu Kerrn
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Old Jul 14, 2011, 09:26 PM
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United States, MI, Macomb
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Originally Posted by Stu Kerrn View Post
I have three photos of 3/4 oz. cloth and microballoons, on these hulls form your opinion. You have to develop your own method, I have only used 3/4 oz. cloth for the same reason some people use airbrushes they don't hide details, 3/4 oz. cloth fits everything like a glove and you must have a hull finished to a high standard, the fiberglass hides little. It is strong, like I said before, I use this method to cover corrugated paper. Thanks Stu Kerrn
That is some really nice work!! That is really some good art you have going there!! That displacement hull you built is a bold beauty!
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Old Jul 14, 2011, 09:44 PM
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Stu Kerrn's Avatar
USA, IL, Morton
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Tolleytime

Quote:
Originally Posted by Tollytime View Post
That is some really nice work!! That is really some good art you have going there!! That displacement hull you built is a bold beauty!
Thanks for your comments, I hope you get out of your basement soon, if not send help message. Stu Kerrn
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Old Jul 15, 2011, 12:37 PM
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Quote:
Originally Posted by Stu Kerrn View Post
Thanks for your comments, I hope you get out of your basement soon, if not send help message. Stu Kerrn
How did you know I was stuck in my basement?
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