My Catalina 309 head system smelled in the first season, and we thought we were attentive to keeping it clean, etc.
Here in Michigan, we put our boats away every winter, and in the Spring, I could see that I had some kind of a leak at the base of the toilet.
I said to heck with it and eliminated all future maintenance issues and all future smells by replacing the toilet with a Thetford porta potti.
Here on the Great Lakes we can never pump
overboard. Pumpouts are the only way to empty the holding tank
. We got kind of tired of going to our local marina, where the gas dock is sort of a circus run by imbeciles. Emptying the porta potti is really easy, and we don't have to do it any more often than we had to get the holding tank
pumped. Saves LOTS of time and hassle and a little money. We seldom go to the gas dock, as I carry a 5 gal. can to the boat to add diesel fuel
The porta potti does NOT smell
It's not at all fussy about which brand of chemicals we use. Just pour some in the bottom and forget it.
It hasn't needed any repair
...if it did, it would be cheap and simple and we could replace the whole thing for 70 bucks
It looks nice in the head / colors match
It's easier to flush than the regular toilet / easier to explain to guests
Did I mention NO smell?
Our Catalina 309 toilet had a drain/exit about the size of a silver dollar. All it takes is one person who can poop bigger than that and the captain has a nasty chore to do. The porta-potti's "exit" is similar to a home toilet. It would take a gorilla to clog the thing. In that case it would be much easier to unclog than a home toilet.
Emptying is quick, easy, and clean, as they've really done a nice job on the design / you'd think it'd be gross, but the chemicals break down the $%^.
Once a year you can put the entire unit on the dock and give a good blast and cleaning with the hose. Overspray goes on powerboat in next slip.
We haven't found a single negative to the porta-potti.