Holding Tank Inspection Port - 1987 Mk 1

[britinusa]

I have just installed a SensaTank Tank Monitoring System on Eximius.

Yesterday I installed the Midships tank sensors - works great although I have not drained the tank to see if it correctly indicates the water level (E - 1/4 - 1/2 - 3/4 - F) it's currently Full and displays that.

I also installed the Holding tank sensors, but that's not working correctly, although the tank is empty (confirmed by looking through the vent in the top of the tank) the display shows 3/4 full.

3 possible causes:
.. Faulty Sensors: I am tempted to discount that as the display shows E if the sensors are disconnected and it shows Full if the sensors are shorted.

.. Tank thickness is > 10mm the limit described in the Sensatank documentation

.. Tank has a build up of crud on the inside where the sensors are located.

When I opened the vent in the top of the tank and shone a flashlight down there, I could see the tank was practically empty (the tank bottom is sloped down to the inboard side of the tank and I could just see a liquid edge) however, I could also see an almost crystalline covering of the bottom of the tank, so I'm guessing that similar crud may be on the side of the tank where the sensors are located.

I doubt the tank has ever been cleaned as there is no access panel installed.


So question: Does anyone know the thickness of the Holding tank in the Mk 1 (1987).

Thanks.

Paul

BTW - I installed a new holding tank vent stanchion and vent hose a few weeks ago, we have used fresh water, not salt water, to flush the loo for almost the past year and we pump out frequently. I mention this because there was NO SMELL when I removed the vent elbow from the tank to peer inside. 

[Stu Jackson]

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So question: Does anyone know the thickness of the Holding tank in the Mk 1 (1987).

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Paul,

It's a Ronco tank.  The model # on mine is stamped on the top.  Call Ronco.

[britinusa]

Thanks Stu.
I found a pic, it's a Ronco B179

Waiting on a reply from Ronco.

Paul

[britinusa]

Nothing back from Ronco, yet (and it's Friday Night)

Planning on adding an inspection hatch, I can measure the tank thickness at that time.

Any reason not to install a transparent hatch? I know, it's kinda gross, but if the sensor does not work then at least I could 'inspect' the level visually.


Paul

[Dave Spencer]

Hi Paul,
Here's a picture I took of a section of the holding tank that I drilled out to add a second vent in my holding tank several years ago.  It looks like the top of my tank is 9.5 mm thick.  I'm not sure if the sides of the tank where I suspect the the sensors are mounted to detect the waste level is the same thickness. 

I see no reason why a transparent hatch would be a bad idea.  I suspect it would quickly become fouled with the tank's contents but a transparent hatch is unlikely to leak or pass odours any more than an opaque hatch. 

[mregan]

I have the Sensatank on my holding tank and it reads fine so I don't think the tank wall is too thick.

[britinusa]

Thanks mregan (where's you info?)

Dave, great pic, thanks.

Ordering the transparent hatch.



Paul

[scgunner]

    Paul,

      Have you ever thought there might be a reason holding tanks don't come from the factory with inspection hatches.

[mark_53]

   Have you ever thought there might be a reason holding tanks don't come from the factory with inspection hatches.

Probably because someone is bound to leave it open and go sailing.

[Stu Jackson]

In our 19 years of C34 ownership, I have never felt the need for an inspection port on  our holding tank.  If I want to see what's inside, I pull the vent hose and unscrew the elbow.

Peggie Hall has reminded us that using a manual head the results are 3 gal/person/day.

I replaced our macerator pump once, about three years ago.

I also have a system that either goes overboard or into the tank, not one that requires going into the tank all the time.

Your boat, your choice.  :)

[britinusa]

Our system is setup with the choice of pump out overboard or via the deck plate, no option to discharge from the Loo to the Ocean.

Paul

[KWKloeber]

    Paul,

      Have you ever thought there might be a reason holding tanks don't come from the factory with inspection hatches.

Mine has an OEM (4"?) inspection plate.  Handy when I want to hose down the innards.  And no, never left off when sailing.

k

[britinusa]

One might want to cover one's butt, however, I cannot contemplate putting the cushions back in place with an open hatch on the holding tank.