What Color is Your Holding Tank?

[snoopy_]

Hello,

I was wondering if the holding tank in my 1990 C30 MKII is a replacement. I see some photos on here that are black, mine is opaque white. Part number is correct, think B123... I see that the opening has about a 1/4” dremeled away, so I was wondering if is newer. I about to undertake a head and hoses replacement.

Thanks,

 

[Ward H]

On my 1993 C30 it is black. My two water tanks are the white opaque color.

 

[jssailem]

Perhaps it is black on the inside. They do call it black water.

But I find it is often yellow.

 

[Peggie Hall HeadMistress]

Sounds like a PO replaced the holding tank, 'cuz Catalina has always specified black for waste holding, white for water. And btw...Ronco Plastics has been Catalina's OEM tank supplier for decades. And 321 would be a Ronco mold #.
Which opening has been "Dremeled?" I'm guessing that's a misguided attempt to repair a tank fitting that cracked due to over-tightening the male thread-barb hose fitting.

Btw, Ward...If your water tanks are still OEM tanks, I'm pretty sure they're translucent polyethylene, not opaque.

--Peggie

 

[Ward H]

Btw, Ward...If your water tanks are still OEM tanks, I'm pretty sure they're translucent polyethylene, not opaque.

Thanks for the correction Peggy. I used the wrong word.

 

[snoopy_]

I was guessing that it may have been replaced, and it is clear/opaque.

I plan on replacing the toilet (head), and the hoses, and I would like to increase the vent as well to route to a bulkhead thru-hull as Peggy suggests (following this thread). Can you re-use the original vent hole instead of drilling a new one?

 

[Peggie Hall HeadMistress]

You can keep the original vent fitting on the tank and replace just the vent thru-hull ONLY if the wan the vent line to remain 5/8". Upgrading the vent line to 1" requires installing a new 1" vent fitting in the tank...which is actually pretty easy, thanks to a li'l doodad called the Uniseal UNISEAL The only other thing you'd need is short piece of PVC that would become the hose fitting.

-Peggie

 

[snoopy_]

Regarding using pvc fitting, I remember reading something about keeping the rise above 45 degrees... why? And is that correct?

 

[Peggie Hall HeadMistress]

Regarding using pvc fitting, I remember reading something about keeping the rise above 45 degrees... why? And is that correct?

Not correct. Ideally the vent line on a black water tank should be as short (< 5'), straight, and horizontal...which is impossible on most sailboats. But the vent line does has to be as straight as possible--no 90s with the possible exception of the hose fitting on the tank, only a single sweeping turn if absolutely necessary...and rise no more than 45 degrees, which often requires a vent line that's a bit longer than 5'.

Why? Because the gasses--even odorless CO2 generated in an aerobic environment--are heavier than air...they don't rise. And ambient air outside the boat doesn't fall. That's why it's necessary to keep the line as close to horizontal as possible to provide the exchange of air needed to maintain the tank aerobically and 45 degrees is the max rise that'll allow the gasses and ambient air to meet.

I used to compare a vent line to a hallway with an open window at one end in a house. The air from the open window can't make it around any corners in the hall nor make it up any stairways, even one that's close to the window. Which is why sometimes the only solution is a fan...or, on a boat, an aerator that pushes air through the tank contents.

--Peggie

 

[snoopy_]

Is that possible? To have the vent leave the holding tank with an elevation of less that 45 degrees, and hit the toe rail thru-hull in less that 5’ of run?

 

[jssailem]

It can be, but it may mean you need to drill another hole in your boat if the original sanitation design was one of "Just get it installed", rather than "install a designed system that will work in the real world conditions".

 

[Peggie Hall HeadMistress]

It can be, but it may mean you need to drill another hole in your boat if the original sanitation design was one of "Just get it installed", rather than "install a designed system that will work in the real world conditions".

Actually Catalina does a better job of designing sanitation systems than most production builders. At least they actually put some thought into it even if there's a lot they still could learn about sewage management.

--Peggie