Yes, they do compost but for liveaboard
use, it's typically not complete before you have to empty it. No it does not need anything close to 2 yrs to complete the composting.
Skid marks: How to you avoid skid marks with a the standard marine
toilet with a 1.5" hole in the bottom? You clean it. Generally solids drop in the hole. We have a spray bottle of water to rinse the bowl after every use.
We have the natures head
. It's a 2 gal liquid tank and we have a spare. We can go 4-5 days but usually dump daily as it's not a big deal.
I like the Chead with the two bucket system (we got our natures head
before they came out). While the solids must be emptied more often, it does offer the option to give it a week or two before dumping so the composting is more complete. I don't like the 1 gallon liquid tank though. If you have guests on board, that could get filled very quickly.
Got small flys once but emptied and quick application of bug spray and they never came back.
It's not perfect. You still are dealing with waste but beats the heck out of trying to get the joker valve working while you are head down in the head while the boat is bouncing around with wonderful odors wafting about the small enclosed space.