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FG layup schedule to achieve desired thickness

8389 Views 13 Replies 8 Participants Last post by hellosailor, Jan 19, 2009

dgr

Discussion Starter · Jan 13, 2009

Here's the question: How do I translate thickness of a laminate to a layup schedule?

Sometime in the near future, I am going to have to do some core replacement on my decks. Once I cut into them, I will know how thick they should be and desire to replicate that thickness. Where the core is still 100%, the decks are fine so I believe that I should try to replicate the factory thickness.

Maybe I'm just approaching this from the wrong direction. But, I can't figure out how to measure the thickness short of doing a test layup. I could mess around with this and come up with something but, if there are formulas to get where I need to be, I'd like to work from that direction so I can get enough of what I need the first go around.

Thank you

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NOLAsailing

· #2 · Jan 13, 2009

If you want to be very precise, you can try to contact the builder and find out the laminate schedule.

However, that probably is not necessary. If you're a little over/under, it's not hard to sand it back down/build it up while fairing for paint prep. For most decks, 2 layers of 1708 biax topped with 1 layer of 10 oz cloth works well.

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idontwantanaccount

· #3 · Jan 14, 2009

Contact the fiberglass manufacturer. Some general, nonspecialty cloth info was posted at the link below.

Fiberglass thickness - Boat Design Forums

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dgr

Discussion Starter · #4 · Jan 15, 2009

Thank you for the replies

I can't contact the builder as it is a Columbia. I really don't need to be that precise. I just want to have a general idea so that I can lay wet-on-wet when I do this. In the end, I want to avoid a springy deck or having to sand a whole layer off because I guessed wrong.

idontwanna,
Thank you for the link to the chart. That's a great starting point.

With all the experience on here, I'm surprised that those that have done this don't have an opinion. I'm thinking I should phrase this in such a way that what I'm trying to accomplish sounds like a really stupid idea. That seems like the best way to get a lot of responses :laugher :laugher

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NOLAsailing

· #5 · Jan 15, 2009

I just want to have a general idea so that I can lay wet-on-wet when I do this

dgr - you're not going to want to build up all of the layers at once as the excessive heat can compromise the laminate. Depending on the weight of the glass, you'll be limited to 2 or three layers at a time.

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dgr

Discussion Starter · #6 · Jan 16, 2009

Jason,
Thanks for that. So, what are the options to avoiding amine blush and insuring the highest bond strength between layers? Or can I go polyester or vinylester and just wax the last layup. It seems to me that everyone that does this type of work is using epoxy but I'm open to whatever will achieve the desired end result.

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NOLAsailing

· #7 · Jan 16, 2009

The amine blush is easy to address. Just spray the cured resin with water and srub it with a scotch brite pad - you don't need to scour it, just rub it down. Not a big deal (don't skip the step, but a decent scrub will remove any of the blush).

Forget poly or vinylester resins. They're OK for an initial build, but they have very poor secondary bonding characteristics. For a repair, epoxy is the only way to go.

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sailingdog

· #8 · Jan 16, 2009

Some epoxies don't blush or have a much reduced blush, like MAS epoxies...Or you can choose to lay up while the first layer is still tacky, before it cures fully.

The main reason most people go with Epoxy resins is because Epoxy resins have much better secondary (adhesive) bonding characteristics than do vinylester and polyester resins. Polyester and vinylester resins are much weaker when they can't form primary (chemical) bonds and have to rely on secondary (adhesive) bonding.

Two things to be aware of. First, epoxy resins deform and weaken at much lower temperatures than do vinylester and polyester resins, so you need to paint or gelcoat epoxy resin work in fairly light colors if the work is exterior. Second, epoxy resins are also subject to UV-degradation, so they need to be coated with something to protect them-paint or gelcoat.

dgr said:
Jason,
Thanks for that. So, what are the options to avoiding amine blush and insuring the highest bond strength between layers? Or can I go polyester or vinylester and just wax the last layup. It seems to me that everyone that does this type of work is using epoxy but I'm open to whatever will achieve the desired end result.

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dgr

Discussion Starter · #9 · Jan 16, 2009

SD,
Are you suggesting I do this from the inside?

Next thing, you'll be telling my I'm short two hulls

Seriously, thanks for the pointers. Laying up while the previous layup is green was what I was hoping to do. I will definitely be painting my deck white or some other non-dark color.

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CrazyRu

· #10 · Jan 16, 2009

If you use major brand names epoxy - West system, MAS etc, there is no amine blush when using slow hardeners.

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sailingdog

· #11 · Jan 16, 2009

You're short two hulls, and a couple of cookies shy of a dozen.

BTW, AFAIK, West Systems still forms an amine blush, although less of one, when you use the slow hardener.

dgr said:
SD,
Are you suggesting I do this from the inside? Next thing, you'll be telling my I'm short two hulls

Seriously, thanks for the pointers. Laying up while the previous layup is green was what I was hoping to do. I will definitely be painting my deck white or some other non-dark color.

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soulesailor

· #12 · Jan 18, 2009

You should be able to get an accurate number of layers needed when you grind your deck in prep for the glass work. By grinding your deck glass back you will clearly see each of the layers in the laminate.

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amunro

· #13 · Jan 19, 2009

FG layup

Ancient Chinese secret: Drill a core sample and burn it. The resin burns away and leaves the glass intact. Peel them apart carefully and you'll know exactly how your boat was built.

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hellosailor

· #14 · Jan 19, 2009

dgr, call the folks at West Systems or go to their web site. They have this all documented in their archive of articles, and if you call their tech support department they'll help you figure out exact numbers and a layup schedule--even if you haven't bought any materials yet.

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