I just finished a similar bottom overhaul on "Aquila." Boy, you aren't kidding about the time, effort and cost associated with that kind of work, but boy am I jealous you got to flip you boat over! For the second half of my project, I got to hang it on a crane, which was a lot easier than doing the work on the trailer.
I started with Franmar Soy Strip, which did a great job on half the boat and did nothing on the other half. It was strange. So I then had to sand off all the paint, which took well over 100 hours. Best investment I made for this was a Bosch half sheet sander. I also learned that you should never take a belt sander to the bottom of your boat unless you really like fairing.
After removing all the paint, next came the fairing. I spray painted the whole boat in a bright blue, then longboarded it to see where my low spots were. Then I filled them. Then I repeated. I templated my keel and discovered that it was pretty close to symmetrical. So I just faired it smooth and left it at that (which was still a huge job, by the way). I also fiberglassed in the keel to hull joint, and faired it into the boat. It was slow going because I had to wait at least a day between coats of fairing for it to dry, sometimes longer on the colder days. I'll tell you though, from expirementation, that the West Systems epoxy and fairing is well worth the extra coin. Applies easily and sand like butter. For the majority of what I faired I used the micro-light "410" filler.
After that, I hit the boat with two gallons of Interlux Interprotect (about 2.5 coats). I had originally wanted to go to bare gelcoat, but due to extensive damage that was not an option. After priming with the Interprotect, I sanded the whole boat with 120 grit, then wetsanded it with 120. Came out pretty darn smooth. I should have put more interprotect on to begin with, however, as I sanded through it in spots. But at $100/gallon...
Then, I sent her over to KKMI to have VC Performance Epoxy sprayed. I ended up with 4 coats of that stuff. The time I spent prepping the Interprotect for this topcoat was worth it in the end, EVERY imperfection shows through on this stuff.
I then moved on to wetsanding with 220. I then move up to 400, then 600, then finish it with 1500, then coat it with McLube Hullkote to protect the finish. It is very shiny! This is still in progress...
In the end, the bottom is not perfect. But it is much better than it was and something I am proud of. All in all, I estimate at least 250 man hours were spent, and I don't even want to start counting the amount of money I blew. The good news for me though is that Aquila is now dry sailed, so the bottom should not need any attention for a long, long time assuming regular maintenance.
I consider it a valueable experience having done the job, but I can tell you next time I'll probably just bust out my checkbook. Or better yet, buy a boat that is already on a trailer and has been faired. Whatever the extra cost to buy the boat, as James pointed out, is going to be FAR less than the money you will have to stick into it, not to mention time (and hey, time is money, right?)
Anyway, great work there James, I love that octopus! I like your documentation. I wish I had that available to me before tearing into Aquila! I just wanted to share my experience with those who may be considering taking on the job. If anyone has any questions, feel free to contact me. I think I know more now about Santana 22 bottoms then I ever wanted to (I saw it in my sleep at one point, no joke).
See you all out on the water!