No one mentioned 1-year vs. 2-year. I would think most people in Rockhall haul out each winter and would be just as well (better?) served by a 1-year paint....
...Sorry I wasn't more clear about this previously: I've always used multi-year paints. My routine is to do two coats on the bottom in odd numbered years, and do a heavy polish/wax above the waterline in even numbered years. I don't like doing both in the same year because I usually like to do the wax very early in the spring, and I don't want to risk getting wax on the bottom before painting. This year I may have to do both, so I need to paint first.
Much as I'm a creature of habit, there's no law that I can't paint every year. It's a bit of a pain to mask off the waterline, and it's just nice not to have to endure the chore every year. But since I'm in a heavier fouling area than I've been in before (for hard growth), a fresh coat every year might be the safest protection since I haul out anyway. I do know that the real cheapo stuff that Herrington Harbor used (AkzoNobel Nautical Proguard Ablative) worked GREAT for one season, and there are only a few thin spots on my boat, so a heavier coat in those places and a light thinned coat over the rest of the boat might be just the recipe. And by using the same stuff, I don't have to worry about compatibility. So I may just stick with it for ~$80/gallon.
By the way, when I say it worked great, I was amazed to see my boat come out of the water with absolutely no slime at all. No hard growth either, except for prop and shaft that were protected by Zinc Barnacle Guard. It's possible that the bottom was sloughed off by the 14 hour trip just prior to haulout, but that's a good sign!...
I had an extensive discussion this week with the Interlux phone tech in Florida. As a result of that discussion, I think I'm going to continue with the same paint that's on the boat now: Nautical ProGuard Ablative made by AkzoNobel. Here's why:
I started by telling the guy that the ProGuard worked great for - first time I've ever pulled out my boat and found NOTHING on the bottom. I'd never seen that before on my other boat. He said, "Yeah, I've heard that about the ProGuard before."
Drawing on my paint formulation background, we got into a discussion of the AkzoNobel's design philosophy for ProGuard, including specific compositional details that are disclosed on the MSDS. Specifically, I zeroed in on the fact that the composition discloses natural rosin as a binder, but no synthetic polymer resin. He told me that AkzoNobel designs ProGuard as an industrial paint to be sold directly to boat yards at a lower price point than their Interlux brands. They keep the Interlux brand off the paint so they don't erode their margins on the Interlux lines.
He said that the rosin is less expensive than synthetic resins, which makes the paint a little less expensive to manufacture, and makes it a softer ablative than their multi-year paints. They refuse to guarantee it for more than one season because it ablates too fast to last two seasons on a powerboat at 20-30 knots. But he said that it's potentially a perfect paint for sailboats that only see a max of 8 kts STW, and would likely last 2 seasons or more unless you're crossing oceans and sailing 24/7.
The key point seems to be that most multi-year ablative paints are engineered to be harder ablatives that can withstand high speeds and trailering of power boats, which make up the bulk of their market. But this design philosophy is the wrong thing for a sailboat, which would likely be better protected by a softer ablative.
It's also very nice that it can be cleaned and thinned down using ordinary Xylene and/or Acetone from Home Depot, instead of custom blended thinners. It's definitely not as good as soap-and-water cleanup of a water based paint, but at least you're not getting gouged by needing to buy quarts #120 thinner or equivalent.
Based on this advice, I'm going to continue to stick with the $80/gallon ProGuard Ablative paint. I'll put a thin coat over the whole boat, and two or more coats in the thin spots, wear points, and along the waterline. I'll continue to judge how it's working after multiple seasons, and switch to a different paint in future years if I need to.