Here it is, March, and sailing is practically around the corner! Time to revisit this issue.
@Peggie Hall HeadMistress I bought a copy of your excellent book and learned quite a bit, it's well worth the money to buy and the time to read.
I also reviewed this thread and others:
https://forums.sailboatowners.com/index.php?threads/water-to-flush-the-head.189004/
As Peggie explained in her book, there is no one best system for anyone. I'm still struggling to know what to do.
The current setup is a manjal Jabsco that takes in sea water through a seacock Simple enough, but for reasons I'll never understand, intelligent adults can neither figure out how to work it nor remember how once it's demonstrated. All the confusing markings around the pump handle sure don't help. And remembering how many times to pump? And kids? I have a friend who won't let anyone flush, he tells them to do their thing then he goes and flushes for them.
Anyhow, I have some priorities and they may conflict. I'm looking for a system that is:
1 - Dead simple to operate
2 - Uses fresh water
3 - In the event that I run out of fresh water, can be used with fresh water
The "Fresh Flush" is out. It's big and can't work with seawater any better than anything else, or at least they tell you not to put a switch to draw from a seacock even downstream of this thing.
The Raritan Fresh Head comes back to mind. It's easy to use. You press a lever to add water and pump a handle to vacate the bowl. Downside is that I then need to carry fresh water.
Freshwater weighs 8.34 pounds per gallon and a flush uses about half a gallon or so. If I upgrade my holding tank to 35 gallons from it's current 10 (which still is not much) then I need to carry maybe nearly 100 pounds of fresh water. On a light air race day I prefer not to have to do that (7 people flushing 3 times each is 11 or so gallons).
My sink drain seacock is below the waterline, so if I were to plumb a tee connector at that seacock and feed the toilet from that, I could have people flush with fresh water when we have it, or rinse it with fresh water at the end of each day. That gets away from the whole dead simple thing, especially if a stopper ends up being required to keep air from entering through the drain..
I'm wondering, if I install a Raritan Fresh Head and for whatever reason was out of fresh water (other than drinking water) and wanted to flush with sea water, could I just pour it into the toilet and flush? This is what I'm leaning toward and would appreciate thoughts.