I thought there had to be a padlock on the dump to prevent
it from being dumped inside the three mile (or whatever) limit.


************

It's supposed to be "secured". (Depending on the Coastie doing the
inspection, a chunk of wire or a zip tie may be sufficient). By the
same token, it was supposed to be "empty" at the boat show. You will
find a lot of show boats where the Y valves are not wired shut.

Some builders use an ignition switch for the macerator dump, with the
theory that if the key isn't in the switch the system is secured until
3 miles offshore.

I suspect that a lot of guys scramble down into the engine room to make
a few "adjustments" when the CG hauls them down and wants to come
aboard. Unfortunately, long brown trails of evidence from illegally
pumped holding tanks are common sights around here in the summertime. I
don't know whether that's because the waters are often calmer and this
stuff shows up, or whether it's because the guys who only take their
boats out twice a year and don't know any better, (or don't give a
damn), do it in the summertime.