Thetford
I fitted a model called "Aquamate", made by Thetford. They have a web-site, and you can check out the various models they have. Mine comes in two parts, the top has the seat and a holding tank you fill with water, maybe 4-5 gallons. After use you open a sliding gate valve, that empties the bowl into the bottom half. You flush it with a bellows type plunger that swooshes the clean water around the bowl, and after your done you close the valve. So far, after two seasons with it, no odors or leaks. You get a chemical, you're boatyard probablby carries it, that you put a few ounces into the bottom before the first use. It's fine for an afternoon, or even a few days if not used by more than one or two people. It comes with clips to attach it to the deck, which you should do, as it is top heavy when the water is in the upper, clean, half, and the whole thing can go flying if you heel over suddenly. After your done you take the lower half home, or to a pump out station, and it's got a pipe to dump it, and a button you press to get the air going into it to keep it flowing. That part is not for the faint of heart. But they're great little items. Not too expensive at all, either. And they're really portable, so you could even take it car camping if you wanted to.
