Jared,

Graphite coats don't add strength, they add scratch resistance. They do this by making the outer layer of the boat slippery, so slippery that sharp objects can't get a good purchase to start scratches. A graphite coat is actually softer than epoxy alone or paint.

Since paint is less slippery than graphite, painting over the graphite defeats the purpose and that's why no one does it.

Sanding graphite is an unholy mess. Fill coats need lots of sanding. That's why nobody puts graphite in their fill coats.

If you're going to be painting, what you want in your fill coat is phenolic microballoons. They make the coat lighter, cheaper and easier to sand. They are also very strong in compression and will resist dings.

The real answer is to accept the fact that the boat will be scratched and be prepared to refinish it when it needs it.

Have fun,

Laszlo

i have built and paddled many of the CLC kayaks a lot.  for me, the most important modification to keep the boat nice is putting dynel rubstrips on the bow and stern keel lines:  

http://www.clcboats.com/shop/products/boat-building-supplies-epoxy-fiberglass-plywood/kayak-gear-accessories/kayak-rubstrip-kit.html.

i also would install toggles to make the boat easy to carry.  that will also help avoid a lot of damage.

http://www.clcboats.com/shop/products/boat-gear/kayak-gear-accessories/kayak-toggles.html

unless you are litterally running the boat up on the rocks, the rubstrips will protect the boat where it is most likely to come into contact with stuff and they work well.   the toggles will make it easy to carry with a lttle help.

all that said, it's not uncommon to do a little work after each season to repair deep scratches and to even substantially re-finish the boat every 4 to 7 years.  the cool part is that these repairs or refinishings are easy and can restore the boat to 'new status'.  for my kids boats, i just keep the paint and varnish job simple so its easy to clean up.

   Thanks Lazlo for  clearing up some of my preconceived ideas on graphite. Now I have another question though, if I go with graphite coat say roughly waterline and below  it will still need a UV protection coat, is that true? And if that is true, do you varnish over the Epoxy graphite coat? If that's true, doesn't The varnish then diminish the properties of the graphite the same as paint would?

I may just have to give up my graphite ideas and go with the rub strips.  And yes, I fully plan on doing lots of repairs. That's just the nature of having kids, nothing is nice! 

Jared

I incorporated a black graphite coat from the garboard on down as part of the aesthetic.  It's bright red above and looks great.  The graphite bottom has really come in handy since we have rocky beaches here in the PNW instead of sand.  

My understanding is that the graphite epoxy is somewhat UV resistant in that only the very thin coat of epoxy on the surface gets damaged and the graphite absorbs the rest immediately.  Nothing evidently really adheres to the graphite anyway.  I had originally planned on storing my boat upside down in the back of my pickup so that it sort of acts like a camper shell.

Skully's right, the graphite acts as a UV absorber, so no varnish needed. Here's my WD12 getting it's graphite bottom painted on. My wife's 16LT in back also has a graphite bottom.

This bottom served for 7 years with minor touch-ups, then got a complete new coat as part of a sabbatical refinishing project.

Laszlo

The Dynel rub strips, as suggested above, are great where they are used, on the bow and sterm stems. But they won't protect from midship gouges that happen when you scrape along an unseen rock just below the surface. If you want a fairly bullet-proof bottom coat, consider a mixture of epoxy and aluminum oxide powder, sold by Gougeon Bros. (West). The caveat is that it has to be applied very carefully and smoothly. Once it cures, you'll see how tough it is -- it's virtually impossible to sand! I used it on the bottoms of two cedar strip kayaks (Wee Lassies), and I'm very pleased with it. By the way, it cures to a greenish-gray color, which I consider more attractive than the blacm-weathering-to-dark-gray of the graphite.   

Aluminum Oxide powder from Goudgeon?

No, I think you mis-typed.

They sell powdered Aluminum metal as an epoxy additive, and you'd be correct when you suggest adding this will make a hardened epoxy coat vitrually impossible to sand.

It's tough stuff used this way, almost like having Aluminum cladding on whatever you apply the augmented epoxy to.

Aluminum Oxide has its place in our hobbies, make no mistake! It's the abrasive applied to (one variety at least) what is commonly referred to as sandpaper.

Be cautious when using powdered Aluminum though. As a dust dispersed in air it's flammable.

   I appreciate the information guys. It appears now that I have some more homework to do. 

This was before I painted the top two panels.

  Hey, SPClark, you are absolutely correct. I misremembered! It is indeed powdered aluminum. Thanks for the correction.

That powdered aluminum additive sounds interesting.  Does it significantly add to weight or drag?

Hooper Williams - Brevard, NC 

 Hi, Hooper -- The powdered aluminum is no heavier than any other powdered epoxy additive, practically speaking. I suppose if you took equal volumes of the aluminum and another additive and compared their weights, the aluminum would be heavier, but we're talking about ounces, not pounds. As long as you apply it smoothly, there would no additional drag. If you wind up with lumps or bumps, you'd get the same additional drag as with any other coating applied with lumps or bumps. I used it as my final fill coat, the last application to fill the weave on the bottom. The next time I use it, I will try a pruduct called PeelPly, which is a thin sheet that you lay over a final coat before it cures, then peel off, leaving a smooth coat behind. On balance, I'm much happier with the somewhat imperfectly applied aluminum/epoxy on my two Wee Lassies than with the graphite/epoxy, which is much more smoothly applied on my family's four Wood Ducks. But you really do need to be careful. Once it sets up, it's permanent. 

 Good information.  Thanks Jim.

Hooper 

   What kind of a ratio do you use with the aluminum powder?  It sounds like it gets fairly pasty as opposed to having a "runny" consistency like unthickened epoxy. Also, my assumption is that it can be painted over without negating it's useful properties unlike the graphite. Is this accurate?

Jared