Hey Mike,

Sorry I couldn't finish answering your points, something came up.

From the various comments, I gather some of the guys would rather sand and wax. I respect a guys' right to do things as he sees fit. But I would have to say I disagree on several points with some of the methods discussed here; not as a matter of choice, but rather because I think they're either incorrect or ineffective. I've been puttering around with boats for about fifty years now. And as Greg noted I'm an autodidact so I'm pretty interested in learning. Boy you asked a lot of questions. This is gonna take me longer than polishing my hulls. For what it's worth this is what I've learned about caring for plastics exposed to the sun. I hope the following will answer you questions.

1.) I've used 303 Protectant on many watercraft, for many years. Properly applied, it seeps into the hull depending upon the porosity of the gel coat. The surface film will wear off with use (water, wind, skin, anything that rubs against it) over time. That's why I reapply it every so often, throughout the season.
2.) Similarly, Vertglass too is absorbed into the gel coat, depenent upon porosity and it's remaining residue will also similarly wear off.
3.) My understanding of the two, from a chemist's perspective is, 303 possesses superior anti-oxidant blocking agents. Both are applied the way. 303 is also quite a bit cheaper.
4.)The effectiveness of both is contingent upon proper surface preparation.
5.) Depending on the number of coats, they both create a "slippery" effect on the hulls. The first couple of sailings after the original application of 303, when I trapped-out, my feet felt like they were resting on ball bearings. I had almost zero traction. So now I coat the hull side where my feet rest when trapped-out, with a thinner coating and rub it in well, removing all the excess. I've only used Vertglass on canoes, kayaks, and runabouts so I don't have personal experience with how exactly how slippery it is underfoot.
6.) For the purposes we are talking about, that is, "esthetics" and nothing else, I would never sand the gel coat of my hulls. I don't care what grit is used. Period. The sun is already actively destroying my gel coat, I don't want to assist it in that regard. If it's just about shiny hulls, don't buy sandpaper and DON'T SAND YOUR HULLS. I'll get to abrasives in a minute.
7.) PREVENTATIVE MAINTENANCE. (I can't use the quote tool, to reference your particular question, so bear with me.) Maybe some confusion on this thread is coming from not separating two distinct topics: ongoing hull maintenance and hull restoration work. For example, I've got a 2005 F17, so practically speaking I don't have hull oxidation (yet). To prevent oxidation I do preventative maintenance at the beginning of the season by applying 303 with a saturated rag and wipe down hulls, spar, boom, beams, stainless metal, blocks, rudders, dagger boards tiller bar & stick, and coated shroud lines and forestay. I also coat the hulls once every couple weeks or so when I'm done sailing for the day. I just wipe the hulls down (I don't crawl under the tramp) with a rag damp with 303, not dripping wet, and kind of just polish the 303 into the boat. Maybe takes me ten minutes. Prior to launching this spring I flipped the boat and gave the bottom of the hulls a real thorough rub down and have repeated that once this summer. I'll do it again this fall when I put it to bed, so it will be ready for next spring. The only reason I do the bottoms is to prevent (or maybe I should say, lessen) stains, dirt, and crud from attaching to the hull bottoms.
8.) RESTORATION. I also bought five older cats this spring. The hulls were in varying conditions of deterioration. So in this example I had a lot of work ahead of me. To loosen and remove the oxidant I used a fine grit rubbing compound. I don't use sand paper for this because a.)the slurry doesn't "plug up" like it does with sandpaper; b.)I can get very fine abrasive compounds in an emulsion that floats then over convex surfaces far better than fixed sandpaper; and c.)controling the amount of pressure needed, especially on undulating surfaces, can be done more effectively through the sensitivity of one's hands in a way that is far superior to the work produced by a scrub pad mounted on a buffing machine. Commercial operations almost always use buffers when applying abrasives and some of these guys are really proficient. But you and I, saiors undertake this once, twice, maybe three times in our lifetime. You think we get proficient? The only thing we get good at is cutting off half the remaining gel coat the sun didn't get to yet. From experience a softer touch will control the removal of the oxidant from the still solid gel coat. The goal is to removed the damage, not the remaining gel coat. Take an old thin rag, ten or twelve inches square, fold it over until your hand pretty well covers most of it, pour the coumpound on the rag until it can't hold any more, and start rubbing in circles. Keep adding coumpound to maintain a slury on your work. The rag helps hold more slurry than your hand, but it's your fingers that keep telling you to push harder or lighten up. Remember all you want to do is to remove the broken down crud. And you can't see it because it requires magnification. Figure you'll do it only once to your boat so spend a saturday morning and do it right and be done with it forever. I can't tell you verbally how much effort to apply and when to stop. I could only show you. the condition of your hulls dictate that. If you insist on a buffer, all I can say is go easy. They can really make the compound cut fast. Remember with a machine or by hand, the stuff is going to dry on your hulls as you move on to unworked areas and must not only be removed, but the liquid antioxidant must also be applied before you know whether you removed enough material or too much. In order to make an oxidized hull surface shine, it must be abraded. The surface worked with an abrasive compound and cut off all deris, the high points, and irregularities. But it's a double edged sword; we're make fresh scratches on the hulls order to remove existing ones. By using a very fine grit in a slurry, we make microscopically finer cuts as we work the surface, thereby removing the oxidized mat, large cuts and scratches. Upon finishing, thoroughly wash off with soapy water and rinse. Then the surface will be properly prepared for "finishing". Hull color is in the gel coat, if over aggressive sanding didn't remove it. At this point apply the product of your choice and seal the surface well by patiently rubbing it in. Additional coats of either continue to fill the microscopic depressions until the Nth coat leaves a uniform surface and produces a deep glossy appearance. Guys who like shiny now uncap a cool one and sit back and smile contentedly at their own reflection.
9.) Your own experience with your old boat is a great example illustrating what I've tried to say. Polishing an old paint job (fully oxidized by the sun) or nicely oxidized gel coat hulls doesn't work!!!!!!!! Unless your willing to do the correct restoration required in preparation for the finish coat, you'll get, as you said, unimpressive results. You polished a four year old paint job with wax and as you say, ..."and it hardly made the boat look any better". This was because you didn't remove the crud and get down to fresh gel coat. Coming back to the boat months or years later, you dabbed at a spot with some wax and it shined right up. But like Greg's original observation in this thread, wax doesn't last but a couple weeks at best. Why? Because UV breaks wax down faster than greased lightening. Wax isn't particularly easy to apply, and for sure it's time consuming, so why go through the effort for something that doesn't work.
10.) Mike, assuming we're talking about maintenance and not restoration, your twenty foot boat is only two feet seven inches longer than my F17. Ok, maybe it will take you fifteen minutes instead of ten for an occassional hull rubdown.
11.) Unless you have a serious crack that's leaks or threatens structural integrity, or a very deep scratch, you don't ever putz around with the gel coat. Otherwise there won't be any color matching left to do.
12.) No Mike, I disagree with another way to look at our boats is, as you say, by looking at the part of the country we reside in or how much we use our boats. The level of care a guy gives to his boat is his determination alone. So the choice of boat maintenance is yours. As is the amount of time you use the boat. You made an assumption that because I live far north of you I don't sail much. That's not relevant at all. If it was your point wouldn't fly because what you don't know is I've sailed a heck of a lot more than you this year. At least according to how often you said sailed on the weekends; which incidently sounds like a lot of fun to me. I know you weren't aware I took the summer off to sail as a means of doing a more enjoyable physical therapy for some injuries I sustained. My intention was not to say how you should use your boat. Rather I was trying to make a point about me and how I take care of my boat, relative to how I use it. If I lived where you live, I'd go with you, and pull up on the same beaches right along side of you. Hull bottoms are'nt damaged by UV. I'd still coat the bottom of my hulls really well, because it would give them some marginal protection they otherwise wouldn't have. That's all. I agree with your closing sentence: it's the operative idea for a prudent sailor.

I'll be done sailing up here sometime in November. If the hurricanes are gone by then, maybe I'll come down and explore your waters. Though I confess I'm a tad touchy about sailing with sharks. Hope I addressed your points.

Happy sailing
Daniel