Last summer we took our last
boat to
Avalon and stayed a few days. The harbor patrol asked if we had a porta-potty (it was a smaller
boat, Coronado 25). When I said yeah, they didn't even bother to check.
I emptied it twice (very small tank) in the public restroom by the
dinghy landing. I didn't even put it in a bag to hide it. No one hassled me. I generally dumped the tank in the public restrooms in Mission Bay when we were on a ball.
My 'cruising' experience is pretty limited though, so I imagine if I'd done it for a few months, I might have gotten hassled.
I'm even considering a porta-john for our
current boat, which is a
liveaboard. It's
current system is the old illegal variety. I don't mind spending the
money and time to plumb the whole thing, but it seems simpler without, two less thru-holes and one less
deck fitting.