My "final frontier", if you will, is the hull - the chips and repainting/re-gelling (is that actually a word?). Once the chips are repaired, I'd like to paint the bottom and (re-gel?) the topside. The paint on the hull might very well be the original 37-year-old paint, and wipes off as a powder when touched. First dumb question - what prep do I need to do to the bottom before painting?
It's unlikely that you'll be re-gelcoating the boat. It is possible, but getting it to match on a boat that old will be next to impossible. The bottom paint is easy, and there is plenty of advice on this board already. The search feature kind of sucks here, so I use google to find threads on this board.
I doubt that the boat was painted from the factory. The powdery texture you have now is a result of the gelcoat oxidizing. You could wet sand and buff it, but it will oxidize again shortly. If you're talking about powdery bottom paint, that's pretty normal for an ablative paint.
Knowing that the boat will sit on a trailer for a good majority of the year, but may see a few weeks total in both fresh and salt water, what type/brand paint do any of you recommend? I'm looking for economy/durability, but am more worried about beehives than barnacles, if you know what I mean.
I always recommend Interlux Perfection. It's a little pricey, but the durability has been awesome. I rarely put out my fenders, and when I rub the dock it just wipes off with Goo Gone. My boat's been in the lake 3 years and the paint still looks new. On the deck I have a few chips in the paint, the chips that came out still have fiberglass attached to them.
Finally, what the heck do I do to the topside? Again, it's probably the original gelcoat. We live in the desert Southwest (yeah, I know.... I sailboat in the desert - believe me, I get the looks when towing it), so the sun is intense. Is there some miracle gel for refurbishing the top, or am I looking at a complete strip and re-gel? If a full strip, how far down do I go? I imagine not all the way to fiberglass, but I don't know.
You're more likely going to be painting the whole boat. The bottom with the bottom paint of your choice. Keep in mind that some bottom paints don't like to be out of the water. If the boat stays on the trailer, you may want to skip the bottom paint anyway. It all depends on the amount of time the boat stays in the slip.
Chip repair is not done with bondo. Use epoxy such as west system or MAS with fairing fillers. This filler is generally brown and made of phenolic microballoons, so once you start you'll be painting. There are other products you can use as well, but the epoxy/fairing filler sands about the same as gelcoat so it's easier to get it straight.
I used Interlux paint products on my boat, and followed the instructions to the letter.
There is a lot of advice out there, some good, some not so good. Always trust the manufacturer of the paint. Don't be afraid to call their help line either. They were very helpful both before and during my paint job.