R,
They are probably all a bit different but on mine I pull out a safety ring and pull the mechanism up and into the boat. This where it's easy to panic the first few times you do it, a gusher of water (unless you have the type with a flapper valve installed) comes into the boat while your are trying to stay calm and get the plug, which should have been in your hand before you removed the fitting, into the place where the paddle wheel used to be. You will eventually be able to do it with only a cup or so of water coming aboard.
In my case, there is a simple pin that comes out and the paddle wheel drops out and you can clean it up at the sink. I have a little bottle of "transducer paint" that I got at West Marine, I'm sure it's just a small container of bottom paint, and I've painted everything with that. It seems to help some, but that varies with local conditions I'm sure.
The best way I've found to keep the paddle wheel from fouling is to use the boat about twice a week!
Take care, DanM.
