Just a bit more thought.
I have used several types of marine sanitation devises.
-Electosan to overboard discharge-
-Straight overboard Discharge from head-
-Fixed holding tank with freshwater inlet and fixed head-
-Heads that use air pressure to push "it" down and out (microphore system) -
-The bucket-
-Hang it overboard (for both #1 and # 2)
My experience and opinion:
When I was younger and single:
I liked the "hang it over" and "bucket" option. It was easy to do and easy to keep clean. It really did not matter what size of boat.
When I was married I still liked this option, but the wife did not. This made the aforementioned not an option. Now We prefer straight overboard discharge. It is easy to clean and the smells are very minimal. Easy maintenance too if you get a good head and maintain it. This is illegal in most areas except offshore.
Several boats I have worked on as a Captain have had Electrosan. You pump directly into it. It macerates it up, electrically charges and kills bacteria. Then it pumps it overboard. This is legal in most areas. No holding tank required. This system is convenient if you have the battery to run it. The space to install the system is also minimal.
However I do remember my first day as the Captain of the research vessel Ed Rickets on Monterey Bay California. I went below to do my "morning duties." After I made my "deposit" I turned on the Electrosan, and it literally blew up in my face. Chunks of you know what all over me, the electrical bulkhead, autopilot..ect.ect... In short it was not working properly and the pressure built up over the past few days and the plastic tank failed.
I have worked on 15 or so boats that use holding tanks which are pumped out at a dock. On some smaller boats the location of holding tanks and space issues may be important. In general though they work well. However, and this is too big of a however for my nose, they ALL end up stinking. Venting them, hoses that seep out smell, joints to hose connections, all end up contributing to smell issues. Perhaps if I put in a system new, and I was the only one ever cleaning it, and maintaining it, the system would not be so bad. All previous systems had been maintained by multiple individuals.
Porta Potty ?????
I have not used one ever. The idea of its simplicity, mobility, legality, and ability to be cleaned well are all attractive to me. I have also heard from another web site (aol sailing board) that you can plumb a porta potty for overboard discharge. The resale concerne of glassing over the old through hulls is interesting though. But If I go the porta poty route I absolutly do not wont those valves exposed in such a kickable area. I would glass them over. I plan to own this boat for a few more years.
It will be interesting to hear other comments and experiences on this sensitive topic!