Laying carbon fiber in new hull question.

[ScarabChris]

I have a brand new Bonzi 54" Fountain hull. I want to line the inside with carbon fiber. I have some experience with fiberglass but none with CF. Is there a special type of resin to use with CF or can I use the same stuff I would use with fiberglass?

I was going to use West System which I use on my real boat. Such an easy system.

[RayR]

Is the hull epoxy or polyester resin? best to use the resin type that matches.

All the best,

Ray

[Chris Harris]

Carbon lays up pretty much like glass and it will work with polyester, vinylester, or epoxy resins. Ray's right use the same thing the boats made out of. Also depending on the type of weave you get the carbon will be more delicate to work with than glass cloth because it unravels easily, especially the twill weaves. It's not too big of a deal just take your time.

Chris

[befu]

Hey Chris, the west system will work just fine with the carbon fiber.

You have to remember, that there are three parts to a composite, the resin, reinforcement and a binder. The reinforcement is treated with a binder that allows it to work with the resin. Most fiberglass cloth and kevlar is treated for use with epoxy or polyester resins. Fiberglass mat is usally treated for use with only polyester, not epoxy, and most carbon fiber is treated for use with only epoxy resin. Maybe this has changed, but it has been the rule for a long time. Let me know if you find out differently please.

Polyester resin will make a cotton T-shirt hard and rigid, but it does not mean you are getting the optimum bond between the resin and fibers. Standard radials will work on a top fuel drag car to get it down the track, but it is not going to allow for the best performance! Polyester resin will make carbon stiff, but if you are using a fabric like carbon, you should also use the resin designed to work with it. If not, why not just use glass and send the carbon to me!

If you are going to the expense of putting in carbon fiber, do not scimp by not gong with epoxy, you just need to prep correctly.

In a recap, polyester resin leaves a thin layer uncured (air inhibited), so the next layer chemically bonds with the previous layer (in an unwaxed resin). Epoxy is a physical bond, so surface prep is important.

Either case, what I would do is to lightly sand the inside surface of the hull. If it is polyester, this will remove the uncured layer gumming up the sand paper, and roughing up the cured resin underneath for a good mechanical bond. If it is epoxy, it will rough it up also for a good mechanical bond.

On the layup, brush the surface with epoxy. Then lay the carbon in and resaturate it with resin. Use the brush and work all the resin back out of the fabric that you can. Cloth should use about its own weight in resin for a proper cloth to resin ratio. 5oz carbon will take about 5 oz of resin when done, plus what is left in the brush and cup, so maybe 6 oz per square yard if you can spread it out enough. Corners make it harder and will use up more resin. A thick layer of resin with a glossy surface is just extra weight.

Hope this helps, and if anyone one the site who has more composite technology knowledge can shed more light on this or correct me where I am wrong, I would also appreciate it. I love learning about this stuff!

Brian

[ScarabChris]

I guess I need to find out what resin is used in the Bonzi hull. I just emailed them with the question.

[jcald2000]

Doesn't matter, Just sand and use a Good epoxy.

[ScarabChris]

Doesn't matter, Just sand and use a Good epoxy.

Thats what I did, I happened to have some 1:1 epoxy resin from Fiberglass Coatings in my garage. Left over from a project on the real boat. It came out fantastic.

The boat is made from polyester.

Thanks for the tips.

[tiqueman]

Epoxy will bond to poly, but the other way wont work, so your fine w/ epoxy. Also another trick to add to Befu's great write up, when your all finished, take a wadded up tissue and blot out any access resin thats left. This leaves a very nice finish and makes it a very even finish, instead of having areas that look more wet or puddled than others. I just learned this a couple months ago and is one of the best tricks Ive learned in laminating.

[Gerwin Brommer]

I use a foamroller to do that.
After the laminat is soaked I use a new foamroller, dry.
I will suck up the excessive resin.
Laying up the laminate with a roller also works better then using a brush to wet all the cloth.

[ScarabChris]

Interesting, I'm too late though. I do have some slightly thicker resin in the low areas but not too bad.