I wrote a complete article...
...about this process about two weeks ago. It's titled 'H23 Keel painting - Interlux's solution'. Check the 'smaller boats' forum, or the forum archives. I will note that I got a lot of advice to be careful with what I used to prime the keel with - Many paints don't adhere to each other very well, so it may pass that the bottom paint of your choice doesn't stick to Rustoleum; it'll flake off after the paint's dry and the boat's in the water. It's a bit more expensive to use the Interlux solution, but if I do the keel right the first time, I should never have to fair/grind it down again-- I will only need to sand the keel lightly and apply another coat of bottom paint. As for Crazy Dave's advice to ignore the bottom of the keel, he's probably right; The first year you use the boat you'll find EVERY shallow spot of your cruising grounds using the "Braille Method." I'm planning on cleaning mine up, fairing it, and sealing it, because I found (while SCUBA diving under my boat) that I have a HUGE pit in the bottom surface of the keel. You can't see it while it's on the trailer, but my keel is on its way to becoming hollow! I'm still scraping the bottom of my boat, and will let you know how it all turns out. If you decide to go ahead and use the Rustoleum, let us know how it turns out!--Jon BastienH23 '2 Sheets to the Wind'P.S. - Congratulations on your purchase of a H23! There's a wealth of information in the archives about this boat, and I have yet to hear of an owner who didn't like their 23...