Pirate,
And, in addition to Winston's observation, you & I are both using American English as our second languages :-)
The graphite powder, as all good things for boatbuilding, is available from CLC here. The six-ounce can is plenty for one boat, possibly even enough for both. Using it is simplicity itself.
First, thoroughly mix up a batch of epoxy and hardener. I like to mix it 3 ounces at a time.Then, slowly pour it into a container holding an equal volume of graphite powder, stopping frequently to stir the mix. It's sort of like mixing the milk with the cocoa powder when making hot chocolate from scratch. If you add the powder to the milk, you get a nasty lumpy mixture, but adding milk to the powder gives you a smooth paste. Same for the graphite and epoxy.
When it's completely mixed, pour some onto the boat's bottom and spread it around with a short-napped foam roller. This will be very quick. Repeat as needed. Once the entire bottom is painted with the mix, tip it out with a dry foam brush to get rid of the air bubbles. Since you willl be doing 2 boats at once, you should have less problem with waste and might be able to eke out both boats from a single can.
If you want to sand between the layers, you need to let the stuff cure hard. On the other hand, if you want to simply put on a second coat, you only need to wait until it is no longer tacky. Sanding with #220 paper will get rid of the orange peel texture that such a thick mix develops. It also kills the gloss, makes it pencil lead gray and make you look like a coal miner. I didn't sand mine.
Two coats should be plenty, I can't imagine needing more than 3. The stuff is very messy. It's a very fine powder which gets blown around by the slightest breeze, turns everything black and is very difficult to clean up. The epoxy mix is also messy. Be sure that you have everything masked and covered before you start, have lots of gloves on hand and clean up and drops on the boat immediatley with a paper towel.
Finally, I used the fine line tape from CLC to mask the boundaries, with the tops of the stitch holes on the side panels as my guides.
Good luck,
Laszlo
PS - here's even more information about graphite/epoxy bottoms for boats