confused about fiberglass layup process

[ondarvr]

Back to basics again.

3/4 ply would be overkill, 1/2 or 5/8 is all that's needed. 1/2 is the normal choice.

Polyester resin alone is almost worthless, so coating the under side with only resin isn't going to be of any value.

The plywood itself supplies adequate strength, the glass is just to tie it into the hull sides and protect it.

Multiple layers of cloth on plywood isn’t an ideal laminate schedule for polyester, stick with CSM as a first layer and 1 cloth on top of it.

[michael pierzga]

A very good reference that is free to download on the net is the Gougheon Brothers on boatbuilding.
http://www.westsystem.com/ss/assets/...k%20061205.pdf
In addition almost every epoxy supplier has a good tutorial on glass types, general scantlings and best practice.
http://www.raka.com/
http://www.systemthree.com/

Hundreds of home boat builders are presently beavering away under clouds of epoxy dust and frequently document there work on sites like

http://www.bateau.com/proddetail.php?prod=PG20
http://www.duckworksmagazine.com/

[sean-nós]

On my builds I used 6oz cloth it's put on dry the day before to let it settle.



Then starting early the next day I give it the first wet out.



let it set for 3 hours and do another and 3 hours later another then cut off any waste cloth with a blade while it's still green.

[SamSam]

10 gals is plenty. I always let the prime coat of resin set up before laminating fiberglass on to it, if I didn't the wood usually sucked resin from the cloth and left dry, resin starved areas.

Epoxy is such a good adhesive, that you can stick FG cloth directly to wood. Polyester isn't near as good an adhesive and odds are that cloth directly on wood can be easily peeled off. That's why mat is always used as a first layer on wood when using polyester, it sticks better for some reason.

Also the 'sole' does add a bunch of strength to hulls, especially in small, lightweight boats like a 16' trihull. What it mainly does, when it is glassed to the hull around all the edges, is stop the hull from twisting. The boat would be surprisingly flexible that way without the sole being glassed to the hull on all the edges.

Which brings up one more thing, no matter which resin you use, and that is be sure the hull is not twisted or bent out of shape by whatever is supporting it. Once you glass it all back together, that will lock in whatever shape it's in. If it's twisted when you glass in the sole, it will have a permanent twist. If the supports are bending in the hull anywhere, when it's glassed there is a good chance it will be permanent.

[tunnels]

Originally Posted by therigwelder

I think i will be using 2 layer of six ounce cloth.I dont feel that the deck i am redoing has signifigant structural impact on the boat.The deck sits directly on stringers in the bottom of the boat.There will be no real weight in the boat other than foot traffic and fishing gear.I really feel i need a watertight surface rather than structural integrity.The area of cloth will be 4 yards,how much resin can i expect to use?i have 10 gallons on hand.when i prime the ply with resin do i allow this to dry before procceding to lay down cloth?i will be priming both sides of the ply but glassing only the topside.this boat was originally done in the same manner except the factory used 3/8 ply and a few layers of csm.I am using using 3/4 ply and 12 ounces of cloth.
.

When you glass take the glass a little way up the sides .
Resin to glass is worked out by weight .
1 kg of glass will use close to 1.25kgs of resin to wet it out !! The size of the piece of material is not relevent its the weight of the glass !!
Mix just enought to do the job and if you need a little more just make a small mix to finish it with !
Differant types of glasses use differant quantities of resin ,but its your starting point !
Your fine glass cloth will use less resin than the chopped strand matt you have !!.

[archiechefaps42]

Originally Posted by PAR

The polyester built boats don't last long, as their plywood and solid timber support structures die fairly quickly. Faster then a whole wooden boat in most cases. The production built craft need only survive their warranty period. It's not uncommon to see boats less then 10 years old in need of major repairs. I put a new transom core in a 12 year old boat recently and repaired stringers and hatch surround on an 8 year old boat a few months ago.

This is all because they don't prime the wooden elements very well, use too thin of sheathing over them, polyesters don't really stick to wood well, isn't especially water proof (take your pick) and generally don't care much about what happens after a dealer sells it.

I have a few older wooden boats, none of which has had a pampered life, all with original wooden decks and all either pushing 50 or over 50 years old.

You can use epoxy, which will seal the polyester, better then more polyester. You can use polyester if you like, but epoxy is a far easier product to work with. Polyester has earned every inch of it's reputation from many, like me, that have had to hack it out of boats and the obvious signs seen during repairs, upgrades and modifications.

Some manufactures are switching to epoxy, while most others have moved up to vinylester. These changes have come hard for the industry as they're more costly. Most manufactures are also substituting wooden elements for man made. Again it's a costly decision on their part, as these materials generally cost a lot more then wood. Simply put they're using vinylester resin because their shop is step up for styrene and MEKP, which isn't necessary at all with epoxy shops. Sticking with a poly base permits these builders, to keep much of the resin and material handling equipment used on polyester. It's a pure economic decision and has little to do with resin preformance.

In the end it's your call, but even the slow to change manufactures are getting away from it. Once you go to epoxy, see it's preformance and ease of use, you'll never look back.

i like epoxy but tight on money. Can i buy in 5 gallon bucket and from were

[rasorinc]

These people seem to me to be the most conpetitive in pricing. And they are in your area so shipping should be low.
http://www.raka.com/ They are in Ft. Pierce, 34982.

[PAR]

Archie, contact me by email (ckick on my name) and I'll get you some epoxy cheaper then Raka. It's in state and shipping is next day to most places within FL.

[therigwelder]

I think i figured out how to post pics on here,let me give it a try.This will be a picture of the boat iam redoing that i have so many questions about.