I don't personally like ozone generators, as I've stated numerous times here on the Forum.
Generally, they don't do much of anything other than draw electricity. If you do get one that is powerful enough to actually do any good at reducing odors on the boat, it will most likely corrode every piece of exposed metal on said boat. Ozone, in addition to being listed by the EPA as a hazardous material, is extremely corrosive - which is WHY it is considered to be hazardous. It wreaks havoc with your lungs.
So if you tend toward asthma, COPD or have other breathing or lung problems, definitely DO NOT use an ozone generator on your boat.