Sand it down to at least 360, 1000+ if you want to win. Like you want to smooth out where it flaked. Rough is more wetted area, and that's drag. Difference between 360 and 1000 is probably less than a missed shift or bad trim, but to be top, you have to put that extra effort in, or at least as much as your closest competitor. If you get into a drag race, you might appreciate that 1000 grit, or kick yourself if you didn't.

Wash all the dust off, all the crap. I use a hose, and maybe some dish soap.

Wipe it down with acetone, which is the solvent for VC17

Paint it with the VC17.

Next year, you might be able to get away without sanding, that's once ever 3-4 years. VC17 is super thin, and goes over VC17 nice. Eventually it gets to like an orange peel, and you have to sand it down again.

One can of VC17 should do.

Hard to tell if you can lower those pads. If you can, lower one, sand and clean under it, then paint. Under the pads is always nasty. VC17 is nice because it dries in minutes. Then raise the pad back up, move to the next. Do the best you can at the bottom of the keel. Don't forget the rudder, that gets the most growth for being in the sun, but also is easier to clean.

You can probably get it all done in a long day, but might want to budget a whole weekend with the sanding. Just paint with the cleaning but not sanding for me is like a long afternoon, but I'll wash one day, let it dry overnight, then wipe it down and paint it the next.

Might want to tape the water line, or just be careful. I tend to error on too low than going over and having it creep up. Tape can give you a more crisp line.