I am replying to this because I have done it on a small scale.  Have not yet done it to the entire bottom of my kayaks.  Hopefully Laszlo will weigh in as he has experience with doing this.

You can get the epoxy and the carbon powder from CLC or West Marine for starters.  You will need to sand the hull down to the epoxy.  Get all the paint off the area to be coated.  This stuff adds weight so don't coat any more than is necessary.  The bottom up to about 1" above the lower chine has been suggested.  Mix your epoxy and hardner as normal.  Then add the carbon power at 30% - 50% (50% being a one to one mix.  Apply with a short knap roller and tip out with a foam brush.  You may need two coats to cover.  Don't sand unless you have a real goober in the first coat.  Sanding will turn the glossy black finish to a dull gray and will make horrible carbon dust.  The resulting finish will be virtually scratch proof.

I installed the carbon/epoxy and dynel rub strips at the bow and stern of both of my kayaks.  One had worn thru the glass at the base of the stem in just a few months.  The rub strips have been on for two years and show no wear at all.  I have also used carbon/epoxy to protect the tips of my Greenland paddle blades with great success.

Good luck

Pail

Pail got it bang on.  I did the rub strips on my SOF and the entire underside (about 1/2" about the chine) on my wife's WD12.  this stuff is AWESOME!  We hit the St. Lawerence this summer for whale watching and I dragged the WD12 with wife aboard over a couple of rocks that sounded like they were ripping a hole in the hull, you can barely see the scratch.  I did however have to add the bow/stern kevlar rubstrips.  The bow on the WD12 is just to sharp to handle the abrasion alone.

One tip (thanks Laszlo) is mix your epoxy, then pour it into the carbon powder.  It mixed much better then the other way.  I used 50/50 and two coats.  I used a small foam roller and foam brush for tipping.  you will get an amazing glossy black finish.  Also, I used MAS Epoxy with West System carbon powder, no issues mixing brands.

My only mistake was that I mixed a larger batch and it started to setup much faster than I anticipated.  I built the WD12 over the winter a heated, but cool shop.  The carbon was applied in early June with much warmer temps.

Link to Laszlo's blog: http://morocz.com/BoatBuilding/DuckBuild9.htm

You guys covered everything, nothing for me to add.

Have fun,

Laszlo

    I want to thank you guys for the very helpful advice on bottom painting.

     I Found graphite powder on CLC website, is this the same thing as carbon?

     Someone also mentioned to put on the second coat before the first coat

      fully cures. How do I know when this is?

         Thanks again  for all your help.

                                                    Clumaho.

Yes, the graphite powder is the same stuff.  Check teh recoat time for your particular brand of epoxy.  Generally, you should have at least 24 hours.  You will need to remove the masking while the first coat is still wet and then reapply before your second coat.

Paul