So, we have seen some more examples of what I call "emotive
arguements."

In many places, public RV dumps are available at shopping plazas, and
in most places, sanitary and storm sewers are the same thing. I don't
do much RVing, but I have spoken to some who do, and the practice of
dumping at public plaza sanitary facilities, with rinse hoses and
signage, is common, even encouraged by mall operators, who want
travellers to eat and shop there come morning, from behind their blue
line in the parking lot. Our local mall regularly has 50 or so stopped
there in season. Most popular tourist destinations do not have enough
camp grounds and charge too much, and can't survive the short season
economically, so the RVers have pressured to make public rest stops and
dumps more available. It's legal. It's also smart, as it encourages
tourism. Boats are recreational vehicles, too.

I like to have options, and taking advantage of local public
utilities when convenient does not make me a polluter. Nor does
building a system with multiple workable options.

Home hardware PVC ball valves are OK by me, I have tried to break the
one I used, and cannot imagine anything short of a really big hammer
being able to hurt it. No plumbing fixtures leak when new, or they
would not be approved for sale. Mine would be cheaper to replace than
repairing any of the "Marine" fittings.

I would never want to trust any water or drain system that couldn't
handle five or 10 pounds pressure, like all the plumbing materials I
know are capable of doing.

Some essentials for a good odour proof system is simplicity, proper
venting, ease of snaking out relatively straight runs in the event of a
clog, and the fewest possible number of joins in the system.

Those who think that boats are not safe because they are not diamond
coated titanium are just plain paranoid, as well as badly informed.
They probably got their money from grandpa, who earned it in a
practical world. Some of these are the ones that want to bond their
metal through hulls to an electrical system, them complain that they
use up zincs too fast. Hint: disconnect the bonding and check the
fittings for erosion every time you wake up in a cold sweat. Sorry if
I'm O.T.

My home made holding tank is 3/16" thick polyester resin and
fiberglass, lined with several coats of epoxy inside. Built from
leftovers, it's cost is about say, 50 bucks, to be fair, including the
through hull hose fitting. I would trust it rolling down 3 flights of
stairs, full of take your pick. The plumbing is stuck together with
Mechanical Joints, which do not leak or smell, being thick rubber and
sewage rated, and are easy to install and remove for hose replacement
if it ever becomes neccessary. My system does not sit neglected, full
of stuff all year on a salty anchorage with the through hull open. The
head brim is above the water line. The lift from the bottom of the tank
to the discharge is about a foot and a half.

When I replaced my septic tank at the farm, I found it connected
together underground with a 4" MJ on cast iron pipe that had been
underground full of sewage for 40 years, and it was like new, even
after a couple of small earthquakes. My boat does not writhe like an
epileptic snake and there is some slack in the system, and it gets
eyeballed often. The only leaky tank I ever saw on a boat was a
commercial polyethelene tank, with a split in the outlet fitting,
possibly due to neglect and frost. The boat I bought most recently had
the wrong duck bill installed, all warped and jammed in where it didn't
fit. Who would do such a thing?

If you ask any successful engineer, he will agree that the height of
the art and science is to do well enough with the least cost. Spending
a million dollars where a thousand would do is not good engineering
unless you have a government pork project.

My tank does not flex when blowing ballast at about 2 pounds pressure.
The method is most satisfactory.

Terry K

P.S. check this out! Do you have a compression tube inside the mast
where the spreader bolt passes through? I lost an SC22 mast because
there was no such detail included by the manufacturer. 3-1/2" of 1"
i.d. tubing would have saved a bunch of trouble.