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The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
Whenever I have the local harbormaster's pumpout boat empty my holding tank, it seems like the tank is never completely emptied. They always report volume removed, and it's always lower than what I would expect from a 17-gallon tank that was nearly full. Plus, it certainly wouldn't "feel" empty by manually rocking/shaking it. Checking the level through the vent fitting confirmed that it was far from empty.
So I decided to remove the holding tank to thoroughly clean it and inspect it. Maybe the outlet was partially blocked, I thought. ESMERALDA had been sitting in a boatyard for three years when I bought her in 1999, so maybe there was even several inches of hard stuff on the bottom of the tank.
Removing the tank was a little bit of a project. The glassed-in marine plywood partition aft of the tank (under the port settee) had to be cut out. That was the hard part. After that, it slid back pretty easily (after removing the hoses) and was able to be removed through the existing access hole in the settee.
There was indeed lots of crap (pun intended) in the tank, only days after having it pumped out. But when I started flushing it with a garden hose, something very disturbing became apparent.
The holding tank is a Ronco B123. It was reportedly custom made for Catalina, and is used in the 25-, 27-, 30- and 36-footers. The tank is still sold by Ronco:
As the photo shows, it's oddly shaped. One end is 11" high, while the other is 13.5" high. The shorter end faces forward toward the head.
The big problem is that the effluent tank fitting is on this shorter side. In other words, there's 2.5 inches of volume that can never be removed! Given that the outlet fitting is at least an inch from the tank bottom, it's more like 3.5 inches!? And since the tank bottom is pitched AWAY from the tank outlet, guess which way the heavy solids want to go?
This discovery blew me away. Why would Catalina plumb it like this? Every tank installation guide I've come across has stressed the need to have the outlet at the very bottom of the tank, even recommending to lower the hose a few inches below the outlet to ensure that the tank gets completely emptied.
The bigger problem is that there's no easy fix. Short of installing another outlet on the aft, lower end of the holding tank and either routing it back to the existing deck fitting or installing another deck fitting further aft, there's no easy solution.
Anyone else come to this realization? Any thoughts or ideas would be greatly appreciated!
1987 FK #5698 ESMERALDA Padanaram Harbor Buzzards Bay
Thanks Eric: I was already having trouble sleeping. Now I'll be worrying over nasty water tank. But if your on domestic well water the holding tank is never completely emptied either. I'll drink from our well but not from Catalina holding tank. I just know this will wake me up tonight.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by buzzardsolo</i> <br />Whenever I have the local harbormaster's pumpout boat empty my holding tank, it seems like the tank is never completely emptied. They always report volume removed, and it's always lower than what I would expect from a 17-gallon tank that was nearly full. Plus, it certainly wouldn't "feel" empty by manually rocking/shaking it. Checking the level through the vent fitting confirmed that it was far from empty.
So I decided to remove the holding tank to thoroughly clean it and inspect it. Maybe the outlet was partially blocked, I thought. ESMERALDA had been sitting in a boatyard for three years when I bought her in 1999, so maybe there was even several inches of hard stuff on the bottom of the tank.
Removing the tank was a little bit of a project. The glassed-in marine plywood partition aft of the tank (under the port settee) had to be cut out. That was the hard part. After that, it slid back pretty easily (after removing the hoses) and was able to be removed through the existing access hole in the settee.
There was indeed lots of crap (pun intended) in the tank, only days after having it pumped out. But when I started flushing it with a garden hose, something very disturbing became apparent.
The holding tank is a Ronco B123. It was reportedly custom made for Catalina, and is used in the 25-, 27-, 30- and 36-footers. The tank is still sold by Ronco:
As the photo shows, it's oddly shaped. One end is 11" high, while the other is 13.5" high. The shorter end faces forward toward the head.
The big problem is that the effluent tank fitting is on this shorter side. In other words, there's 2.5 inches of volume that can never be removed! Given that the outlet fitting is at least an inch from the tank bottom, it's more like 3.5 inches!? And since the tank bottom is pitched AWAY from the tank outlet, guess which way the heavy solids want to go?
This discovery blew me away. Why would Catalina plumb it like this? Every tank installation guide I've come across has stressed the need to have the outlet at the very bottom of the tank, even recommending to lower the hose a few inches below the outlet to ensure that the tank gets completely emptied.
The bigger problem is that there's no easy fix. Short of installing another outlet on the aft, lower end of the holding tank and either routing it back to the existing deck fitting or installing another deck fitting further aft, there's no easy solution.
Anyone else come to this realization? Any thoughts or ideas would be greatly appreciated! <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
I noticed this when I was planning my holding tank installation. What is worse IIRC is that in order to place the exit at the lower end of the tank, it will be towards the aft of the boat requiring a 180 degree turn if you want the pumpout hose to exit up behind the head (out of sight of the main cabin). I can tell you that with the correct sanitation hose, it will be extremely difficult (impossible), to make that happen and keep the hose under the setee.
This is why my holding tank is under the v-berth (v-berth is used exclusively for storage).
And if you do put it under the v-berth, size the tank to the opening (not the available space under the berth) otherwise you will be cutting a bigger opening and designing support for the v-berth cushions.
Wow, That really stinks! (couldn't help myself) How about just ditching that setup and put in a 5gal porta pot. Thats what we have and it couldn't be easier. No stuck valves, Smelly hoses etc. and you gain storage space too.
Thanks for the replies. I guess I opened myself up to some wise-cacking with the fragrant topic :)
I had a porta-potti in my Catalina 22 and I'd prefer not to go that route. I'm on a mooring, and I shuttle enough "stuff" (I almost said crap) back and forth as it is. The harbor's pumpout boat is convenient and makes house calls.
I thought about a rubber, collapsible bag-type holding tank, but it didn't take much research to realize that that sort of set-up is not recommended at all. The bag is not nearly thick and/or strong enough for head duty.
Mark, you hit the nail on the head. In order to install a new fitting on the lower, aft end of the tank, the discharge hose would need to have several low-radius turns to be routed 180 degrees in the opposite direction and mate up with the existing deck fitting.
It seems like the bow-mounted tank is the way to go. Is there any particular tank model that works well and that members have had good experience with?
Would it be possible to back fill the tank with something like silicone/epoxy/something else so the low area in the tank no longer exists? At least that way you've be able to pump the whole thing out. You'd lose volume, but I think that'd be a good tradeoff. If it were me, I'd be looking at a new tank or porta potty, but if you're determined to reuse the old one, that might be an option.
I still use the Port-a-potty with the 6 gal holding tank and use the pump out stations with the big boats. A second holding tank is standing by if the gauge shows full of the first unit and the full unit can be carried sealed with a handle home or to a dump station with a rinse system. No thru hulls and no electrical. Has worked for many years.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.