Hull Epoxy Question

I spent the weekend glassing the hull of my CH17 and am pretty disappointed in the texture. I'm considering sanding the whole thing smooth and adding another coat or two of epoxy. If I choose to do this, to what grit will I need to sand before I add the next coat? Thanks.

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RE: Hull Epoxy Question

Can you be more specific about what the problem is, and what you have done so far? It's hard to respond without knowing more about your case.

It's pretty typical for the first coat of epoxy over the fiberglass to seem rough, as the epoxy has not fully filled the weave in the fiberglass. Indeed, you sort of want this; the alternative is to slop on the epoxy so thickly that you're sure to get runs that harden into glops that do have to be sanded off. 

A second, fairly thin coat of epoxy will go farther twoards filling the weave, and a third coat even farther.  I ended up using three coats on my two kayaks.  Once the weave is filled, it should be pretty smooth, although some sanding will be necessary to make it truly smooth.

Hope this helps.  Or is the problem something else?

RE: Hull Epoxy Question

I've laid down 3 coats and while I still have a few areas that need additional epoxy to completely fill the weave, I also have a few areas where runs appeared sometime after my final "tipping out". Additionally, I had a fly (no joke) land on my second coat and by the time I found him, it was too late. I was able to remove most of the little critter, but alas, the ends of his legs stuck around (pardon the pun).

RE: Hull Epoxy Question

Sand. Sand. Sand. And sand some more.

Sorry.   :-(

Get a sheet- or random-orbital sander, and a LOT of sandpaper, and get going. Start with a fairly aggressive grit (in some areas I started with 50), and work towards finer and finer grit (I ended up using 250). Nothing magic about it; I suspect some people use coarser paper to start, and I know others use finer paper to finish. The key is to keep using fresh sandpaper; you'll be surprised (dismayed?) at how often you have to change it.

P.S. The fly legs just add character! Believe me, you're not the first to "capture" a few insects!



Before you do any sanding...

Touch up the spots where the weave is still showing, then sand. Use an ROS if you have one, sand with 80 or 100-grit paper and watch what you are doing so that you don't over-sand. Change the paper when it seems that you aren't removing much cured epoxy so that you don't maximize your sanding time. Any runs can be easily and quickly removed by using a cabinet scraper, which is basically a really sharp piece of scraping metal. Hope this helps.


Robert N Pruden

RE: Hull Epoxy Question

Any suggestions on how fine of a grit to stop at?

RE: Hull Epoxy Question

220 grit is a good stopping point...anything more and you'll have to go to wet sanding.

RE: Hull Epoxy Question

On my nearly finished boat I lost count of how many epoxy applications it took to fill the weave.  Sanding at the end, I went 80, 100, 150, 220.  I used the random orbital but also went over the thing once by hand at each grit to get the swirls out.  Probably overkill, but I was outside, usually drinking beer and listening to baseball, chatting up all the people who walk around my neighborhood, so it was not bad.

On the "Zen" video, Harris describes hull sanding as taking "a long afternoon".  More like three.  Settle in.  If you think "good lord this HAS to be enough" but have a sick feeling that the hull isn't ready, keep going.

Like I said, my approach is probably overkill.

RE: Hull Epoxy Question

You can Buy additives for your epoxy. US composites has the best prices on epoxy That I have found. I can tell no diff in there epoxy and the "best brands. Get a fairing compound additive for your epoxy, which they sell at an awsome price, and spread this in a very thin layer over your hull. This will fill low areas and make the epoxy easier to sand. there are lots of different additives for every application you will need for your boat building projects. If you learn to use them now it will save you lots of time and make the work easier. Hope this helps! I have built 4 CLC boats and have been where you are at. Try the Fairing compound

RE: Hull Epoxy Question

Buy good quality sandpaper and make it last. How you ask? Most woodworking stores sell a rubber cleaning "stick" that will clean your paper like new. The rubber stick is almost like gum rubber and will clean almost anything out of the paper. Just turn on your sander and "sand" the gum rubber stick and your paper will be clean in seconds. The abrasive on good paper lasts quite a long time if you keep it clean - especially random orbit disks. And the rubber will last for years. I am still using one I bought probably ten years ago.

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