keel material

I have fiberglass mat and resin, and I have West 205. what would work the best to make repairs to my keel befor I paint?
The resin is a polymer base that I read sould not be used on a Hobie. I bought the 205 to fix a small delam and have enough tofill the keel.


thanks to everyone on this site.

I just wrote some instructions on the transom post. Read it and ask any questions that pretains to you here. I'm willing to try and help. In the mean time, look around on the forum or internet search the keel template. You can print them off and draw it on plywood. Cut out the shape with a jig saw and it will help guide you as you sand/shape the keel after laying cloth.

BTW the oz of cloth makes a difference. Such as 40oz, 20oz, 6oz, 4oz. Heavy boat cloth is hard to work and 4oz is cheesecloth that is put on surfboards. It's easy to burn right through.

whats the difference? chemically/molecularly(sp). and which will stay on the glass the best?
I did some glass patching two years ago, as a temp job, just to get me through untill I was able to redo the hulls completely. As I sanded the old auto paint off of the original gel-coat I noticed that some of the resin that I put on was peeling off,particularly where I DID NOT grind all of the gelcoat off.
Did I just answer my own question? Will resin release from gel-coat? even if I ruff it up with #80 grit?

The boat is made using polyester resin (sometimes refered to as fiberglass resin). It's safest to just stick with using polyester resin in order to minimize bonding issues. Epoxy resin should also work, but if you later try to bond polyester resin to the epoxy repair (i.e. you shoot the hulls with gelcoat or do a future repair), you could very likely have bonding issues.

Hull preparation is also critical to getting a good bond. You want to do your repair in a clean, dry environment (if you're working outside, do the work on a day with little or no wind). After sanding throughly, you should wipe down the repair area with acetone to ensure it's clean. After it's wiped down, don't touch the repair area with your bare hands since oils from your skin will contaminate the repair. Same goes for the fiberglass cloth, be sure to minimize skin exposure and dirt contamination. You should be OK bonding to gelcoat as long as it's been roughed up and cleand. But be sure you remove all the old paint.

sm

After thinking about it, this is why Jeremy from Surf City Catamarans said he would stick to polyester. It would take a chemical engineer to explain why polyester and epoxy resins don't mix (application). When you get these kinds of outcomes it's because polyester doesn't apply well over epoxy mixtures. It will do what I think you are describing. I believe there is both epoxy and polyester gel coats, I could be mistaken. This is why Jeremy is right about "I would use polyester if it was mine". For the layman, it's easier to stick to using one kind of resin. If you apply gelcoat (and it's epoxy) it'll stick to it. Here's the mantra about applying glues, Epoxy over polyester not polyester over epoxy.

It is a shame if it's what your describing, peeling it up with your fingernail. I've walked into the boat barn and found that a whole day and expensive material was lost because the machine was mixing the wrong ratio. You could pull the cloth right off the boat like duct tape. And yes if you don't scratch the place you are applying, it'll never stick. That's for anything. It'll only stick in places then it becomes a bear of a time. Resins like the voids in surfaces. If it's flat, there is nothing for it to "grip" too. Prepping is everything.

Polyester is simpler to use but I've seen it crack a lot. Think of the cracks you see in old runabouts where the floor meets the sides. If you don't get the correct mix from the hardener, the finish product of the cured glue is brittle. Especially in hard angles.

Oops. SM answered it while I was starting to write. Sorry, SM. Listen to him. He's right as rain.