New Holding Tank

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January 2003 -- After a lot of thinking and planning, it's time to do the deed.
I haven't been able to use the head for two years!
First, I had to pull the old tank...

Hey, it 's structurally sound and
who cares what the holding tank
lid braces look like!
After it's painted, it will be perfect.

It has a certain Van Gogh feel to it...

I had been wrestling over the location for the new tank for a while.
There's a "hanging locker" and some puny drawers just forward of the head, and I took a real good look at that area to see
if a holding tank would fit in there.

After assembling the bulkhead and knocking together some braces to hold the tank in place...

To the left you can see just how much space is available. It would have been great to use it.

However, after drawing up plans and thinking a while, common sense took over.
I could get a custom tank in there.
I could make it secure.
I could plumb it.
But if anything ever went wrong I'd
never be able to get in there to
fix it, and I'd never be able
to get the tank back out.
Since things on boats always break
sooner or later, the idea was scrapped.

Third time's a charm... I took the model home and
modified it to fit, making it higher and narrower.
This means that I'm going to have to
have a custom tank made,
which will cost three times as much.
Well, without a custom tank
I have to give up on having a decent Nav station,
since the tank is going to be under the seat
and the bulkhead at the bottom
of the picture must be cut to allow access for feet.

Custom tank it is!

To make sure the plan would work, I made a couple of mockup tanks from cardboard. These are the closest fit from Ronco's catalog -- after checking Kracor and a few other tank makers, Ronco had the closest match.

The k/c Stella Blue
enjoyed helping with this part of the planning phase...


This tank (right) didn't fit well at all... It should have gone back home for a cat toy, but it went into the dumpster instead.

This tank fit better, but was still a disappointment because it's too wide.

There's no way to fit it in, build a seat above it and still be able to get into the Nav station.

Another cardboard mockup for
the bulkhead that'll keep the tank in place.

The tank fittings are these 'Shield' fiber reinforced nylon sanitation hose fittings that are made to work
with high-end sanitation hose.

You can see how the tank tilts towards the bottom of the picture so the vents are highest and the outlet is lowest.

The tank is welded up from 1/2 inch HDPE Polyethylene plastic, with a polished smooth finish.
The top fitting extends up
instead of down.
That works for my application. Note that I had
TWO vent lines installed.
Air flow == aerobic bacteria.

... I glassed in the bulkhead, epoxied tape over the holes from the old tank and basically made the compartment secure.

I also painted
the bulkhead with epoxy
to seal the wood,
and smeared epoxy over the edges of the new holes through the bulkhead to seal them, too.
It looks ugly, but no one's ever going to look at it again.
(The holes are way back up
inside a head cabinet.)
The taped-over hole at
the bottom of this picture
is called 'a mistake.'
There's nothing that can't be fixed.

Naturally, I taped the fittings!

Here's the lid to cover the tank, with
the underside painted with
Rust-O-Leum to seal it.

(Right) Saturday, April 12, 2003.
The view from my companionway.
A perfect day to be working
on inside projects!
And no one else is around,
so I can CRANK the stereo.

With the epoxy was all set and
the tank back in I poured polyurethane foam
all around the edges, letting it run underneath before expanding.
Now it won't budge a bit, and the tank is supported on all sides
at all angles.

I used real Sanitation hose for the vent lines. If the tank is more than half full and the boat is heeled hard to starboard, some of the contents might get into the vent lines, so I used the good hose.
Perhaps the vent fittings should have been on the TOP,
but I wasn't sure it would fit.

I also never want to deal with a cracked fitting or weld, so there's some bilge pump hose clamped over the fitting.
Any movement of the vent hose should be absorbed by
the outer hose and not passed onto the fitting.

To those who call me a perfectionist, I submit the following (Right) -->

The main hose is Sealand Odorsafe Hose.

I had a moment of panic looking at the pics below,
since the light made the lettering on the hose look Blue -- but it really is RED.
Good thing, since the good top-o-the-line hose has RED writing on it...

The hose is really, really stiff!

I tried to snake it through the holes where the old hose had run, but it wasn't worth it. Not only would it not bend with the small radius that the old hose had taken, but it would have snaked around and run for about 5 feet, which would make flushing the hose clean a real pain in the ahem.

So there's a new hole and the hose runs straight
from the head to the tank. It's about 2 feet,
and a straight run.

I'll just have to patch that old hole. Eventually.

Here's a shot of the inside of the cabinet, with the camera on Macro Wide Angle and held back against the hull. The compartment isn't this roomy! In fact, this is the first time I've seen that white bulkhead, since I can't get my head in there and had to tighten the hose clamps by feel.

Wow, that's ugly. Perhaps a coat of paint is in order... although I honestly don't think anyone will ever look in there again. It's more like a place to stick bags and bottles of stuff. What the heck, maybe I'll paint it when the weather warms and the humidity goes down.

Using a straight fitting for the output would have meant having an excessive length of hose winding all around under the sink. In addition to being ugly and prone to odor, the hose would have blocked easy access to the sea cocks.

So I bought a right angle Shield fitting, but didn't like the sharp angle. Right angle fittings are 'bad form' for head plumbing, but I really don't see any way around it. Then I had a slightly better idea.

The Forespar Y Valve is up
as high as possible so that even if the tank gets full there won't be anything sitting inside the valve.

I made a 1.5" block for the valve to sit on, to keep the hose runs straight. It'll go on next weekend.

I installed a PVC elbow, and a section of pipe, then a Shield fitting. It's all Schedule 80, the thickest, strongest kind. The PVC elbow has a much smoother inside turn.

My Handy Dremel Tool helped shape that little section of liner to allow
'elbow room'.

Now there's solid pipe about
2/3 of the way up the side of the tank, so that the tank contents will not be sitting in contact with hose. The tank shouldn't be more than 1/2 full anyway, as a matter of good practice. Hopefully, with nothing in constant contact with hose,
the odor issue will be minimized.

To the right is a mouse's eye view,
looking up from the hull.
I'm just playing with the camera!

I built a good brace for the pipe, so that it doesn't stress the
welded fitting on the tank.
No cracks are to be allowed, ever!

BTW, I have a few additional comments about this at the bottom of the page...

Back to the new bulkhead --
I had to do a little bit of "adjustment" with epoxy paste after cutting away
the longitudinal bulkhead
to which it's attached.
(To provide foot access for
the New Nav Station.)

Perhaps it could have been planned better, but I've been busy and can't spend the time custom-forming the plywood at the dock.

Once it's sanded and painted
it will look just fine.

The old deck pipe is getting replaced as well. The old one had a chain holding the cap on, which made it really tough to get a good seal for pumpout.
Besides, it leaked.

This one is branded by West Marine. It's one solid piece, rather than others which require a screw-on fitting for the hose.

I made a deck pad from pre-fab fiberglass from McMaster-Carr,
and put about 20 coats of polyurethane on it. (It was just sitting in the paint room for a few months, so it kept getting more coats...)

I routed a slot in the bulkhead so one can look under the nav station seat and see the tank.

The idea is to take a flashlight (left) and shine it down the inspection port, and thus see the level of the contents through the slot (right.)

Can you see the glow?
Maybe it'll work. The smooth finish on the inside of the tank might help. We'll see how it holds up over the years...
If it turns out to be a bad idea I can just fill the slot up with putty and paint it.

The finish work on the area is part of
the Nav Station project.