Holding Tank, specifically in a CHB 34' twin cabin

[JRC]

Hi


I finally managed to open the (stuck fast) small hatch under the steps down to the forward cabin to discover that there seems to be a holding tank down there. I was looking at fitting a holding tank anyway, so this was a very welcome surprise... perhaps! But it seems to have been blocked off/ sealed.


Does anyone with direct experience of these specific boats know anything about it? Is it reliable? What size approximately? Any information at all?

 

[alormaria]

There is no holding tank in the forward bilge on my 34' Marine Trader DC. There was a prev owner installed holding tank under the bunks in the forward cabin. The hoses were long and stinky. Everything went out.
I relocated that same tank (cleaned up) with new short hoses to it's new location in the engine room up against the bulkhead on a purpose built shelf.



Same basically with the rear head. The PO had very long hoses (very stinky) under the master bunk to the tank at the rear corner of the aft bulkhead. I relocated the tank in a sealed box right up against the mid bulkhead under the master bunk. The hoses are extremely short and very high quality.

 

[Comodave]

I would contact The Head Mistress here on TF. She is the guru on all things related to heads. As to the tank size if you can measure the tank you can calculate the volume. And as far as the hose the only hose to use is Raritan SaniFlex hose. It is absolutely the best hose on the market. Another thing is no filter on the vent, it will block airflow and that is what creates the horrible smell. The best thing is either a bubbler system or a large vent to each side of the boat to promote airflow through the tank to promote aerobic bacteria which doesn’t smell.

 

[JRC]

Thank you for your replies

The tank that I have was built in by the boatbuilders - it is under the parquet flooring in the forecabin, which has obviously never been touched since. So I can't measure the volume as the floor is fixed and I don't know how far it extends.
Unfortunately I can't fit a new tank against the engine room bulkhead as it is covered in battery charging panels, lights etc. Nor against the bulkhead under the main berth in the after cabin as that is also full - a stainless steel water tank fitted by a previous owner.
My only options seem to be either to clear out the PU foam that has been used to seal the forward tank, not an easy thing to do - if, indeed, possible! Assuming that the (fibreglass?) tank itself is still good? The old pipework to was solid plastic plumbing, not flexible, by the way.
Or to fit a new 33 gallon tank under the starboard side seat of the saloon. That might be the easiest option.
If you see us listing to starboard, the tank needs emptying!

 

[Comodave]

Well sounds like you have a big project. I would bite the bullet and get to the old tank. If necessary cut the flooring. By using a narrow kerf saw in a small circular saw the cut won’t be too bad. I have a small circular saw that takes about 4” blades and the blades make a very thin cut. Or even using a multi tool carefully to cut the floor. Then put a piece od S/S trim over the cut,

As to the foam, I have removed foam in a previous boat using a 3’ flexible extension on a drill. I use the drill bit like a router and with the flexible extension I can guide the drill bit around where needed and chew up the foam. I keep the shop vac sucking up the debris as I go. Then a sharpened putty knife to cut large sections out also works well.

 

[JRC]

Well sounds like you have a big project. I would bite the bullet and get to the old tank.

Sounds like an option!

 

[HeadMistress]

It's important that you do whatever is necessary to gain access to the tank because hoses will need replacing if they don't already (they definitely do if they're at least 10 years old and/or stink.) and USCG regs require that you have a means of letting you know when it''s at least 3/4 full. That can be the ability to inspect it visually or an installed tank level indicator if you can't...due either to the tank location or tank material. Tank level indicators that use sensors applied to the outside of the tank are available for a reasonable price.


The steps should be removable...if not, make them removable. If removing the wall behind them provides the access you need, turn it into a removable panel.


--Peggie

 

[JRC]

hoses will need replacing if they don't already--Peggie

Thank you very much for your advice, Peggie. All relevant and, however I do the job, I will make sure it's all replaced and maintainable!
One query which I hadn't thought of before. The longer runs of what remains of the old black water plumbing have been done in what looks like standard rigid grey plastic pipe, such as we have in the house. In the house, of course, we don't have odour problems from this type of piping. In your experience, is it a good idea to use this type of piping in the boat for the long, straight run from the after heads to the forward tank?

 

[Comodave]

PVC is fine for the long straight runs and it doesn’t permeate.

 

[mvweebles]

PVC is fine for the long straight runs and it doesn’t permeate.

I'd add that the grey electrical conduit is schedule 80 and has long sweeping bends available vs the tight bends of white sched 40 water lines. Black ABS "DWV" can also be used, but I don't recall seeing anything smaller than 2-inch. Either are considerably less expensive than marine sanitation hose, and has the added benefit of being a better product for the application if it can be used successfully (rare on a smaller boat)

Peter

 

[88FuHwa]

I have used the schedule 80 grey PVC pipe in combination with the schedule 40 white PVC fittings. Both pipes can be bent with a heat gun. Just don't overheat the spot where you need to bend. It has worked just great for the last 12 years particularly for the long runs. I convert to the flex tubing in tight spots and the connections to the VacuFlush system and thence to the holding tank. My holding polyester tank is, I believe, in the same place as yours. The inlet and outlets are on the front which can be used to clean it out. I also moved the vent to the top of the tank now with a 1" hose to a new unobstructed thru-hull several feet above the waterline per Peggie's recommendation.

 

[HeadMistress]

Your plastic tank is almost certain to be polyethylene, not polyester.

Moving the inlet and discharge fitting to the top of the tank--which would require a dip tube on the discharge fitting (easy to do) would increase the useable capacity of your tank by several gallons. A for cleaning the tank, that's best done by introducing water into it via the deck pumpout fitting.

Merry Christmas (or whatever floats your boat for you).


--Peggie

 

[SlowRide75]

In our 38’ CHB we have a grey water holding tank in the same location. It holds water from the forward cabins shower. It was replaced by the PO so I can’t shed any light what was there before. If you would like I can send you pictures or a video next time I’m at the boat.

 

[jgwinks]

My boat has a waste tank under the galley sole (galley down and forward). White sanitation hose from the forward head and 3/4" copper tubing from the aft head. That run is at least 30 feet. I've never heard of copper tubing in that application. Nearly all the plumbing in the boat is copper, worth a fortune today. The heads are electric with macerators so I guess it works. The aft head was inop so I replaced it with a compost head like we had on the sailboat so I never used the copper line. I capped it on both ends. Interestingly there's a run of white sanitation hose next to the copper that doesn't appear to ever have been connected. The white hose from the forward is still in use, it looks pretty new so no stink yet. Anyone else seen copper tubing used there?

 

[HeadMistress]

This is the first time I've heard of anyone using copper or any other metal tubing in a sanitation system...nor any 3/4" hose or pipe in a toilet discharge line. That's the standard size for flush water INTAKE lines, but all toilet discharge fittings are 1" or 1.5". Solid waste, even macerated, would have a difficult time passing through anything smaller. And then there's the matter of sea water mineral AND waste build up in a sea water toilet discharge line. With the exception of bronze, no metal of any kind is recommended anywhere in sanitation systems because urine is so corrosive it will turn any metal holding tank, even 316 stainless steel, into a colander in 5-10 years. The same would be true of any metal tubing including copper. As for a 30' discharge line made of ANY material...only the high end all-china "thrones" like the Raritan Marine Elegance are capable of moving bowl more than about 6' without a LOT of help from gravity.

And btw...pvc fittings should also be schedule 80, not 40...40 is very brittle, especially when it gets cold.

--Peggie

 

[jgwinks]

That's what I was thinking. However the copper was connected and the hose was not. Anyway, neither one is in use now so it's moot.

 

[HeadMistress]

All that copper tubing has me wondering if the PO might have been laying the groundwork for a mooonshine still! The bilge of a boat would be a great place to hide one disguised as a holding tank. 'Twould have been easy enough to replace the copper pot with a plastic tank when he sold the boat.


My imagination is having all kinds of fun with that idea....


--Peggie

 

[jgwinks]

All that copper tubing has me wondering if the PO might have been laying the groundwork for a mooonshine still! The bilge of a boat would be a great place to hide one disguised as a holding tank. 'Twould have been easy enough to replace the copper pot with a plastic tank when he sold the boat.


My imagination is having all kinds of fun with that idea....


--Peggie

Could be. The plastic tank is brand new, appeared never used.

 

[Comodave]

All that copper tubing has me wondering if the PO might have been laying the groundwork for a mooonshine still! The bilge of a boat would be a great place to hide one disguised as a holding tank. 'Twould have been easy enough to replace the copper pot with a plastic tank when he sold the boat.


My imagination is having all kinds of fun with that idea....


--Peggie

I wouldn’t want to drink any moonshine from that tank…

 

[JRC]

Your plastic tank is almost certain to be polyethylene, not polyester.
--Peggie

My black water tank is definitely GRP (polyester?). Further investigation reveals that all of the inlets, outlets and breather pipes (all on the aft face of the tank) are, or were, steel. I say were because, unsurprisingly, some of them have rusted away almost completely. Also, the tank is not actually fastened in... just a very tight fit. So I'm hoping to cut a hole in the engine room bulkhead and persuade it to slide out.

If and when I manage to get it out, it may be best to replace it with a new polyethylene one with top fittings. We'll see!

 

[Comodave]

It may be caulked in on the bottom to glue it to the hull. Does it move at all?

 

[JRC]

Yes, if I get a rope on the after end or a piece of timber under the forward end, I can move it up and down by around an inch, just! Hopefully once it starts, it might ease a little. This is going to involve moving pipes, bilge pumps and part of the bulkhead to get access, so I'll leave it until the New Year, after the family have returned to their homes.

 

[Comodave]

Yes, if I get a rope on the after end or a piece of timber under the forward end, I can move it up and down by around an inch, just! Hopefully once it starts, it might ease a little. This is going to involve moving pipes, bilge pumps and part of the bulkhead to get access, so I'll leave it until the New Year, after the family have returned to their homes.

Well that is certainly a positive thing. Keep in mind that you could always, as a last resort, cut it up in place and remove the pieces, ugh!!!

 

[HeadMistress]

Although I'm now in my 80s, I'm not too old to learn something new, so I went looking for info on GRP. This is what I found:

GRP stands for Glass Reinforced Plastic or Glass Reinforced Polymer. It is a very versatile material, which has a huge number of applications and uses. GRP is also often referred to as fibreglass (fiberglass in the US) or glass fibre composite. GRP also belongs to a larger family of products known as FRP, or Fibre Reinforced Plastics. I didn't search far enough to find out whether any of those include polyester, but while I'm very familiar with FRP and GRP, this is the first time in 30+ years I've been messing about in marine sanitation that I've seen or heard polyester used to describe tank material. That doesn't make you wrong...just aroused my curiosity.

Btw...if you decide to replace the tank, Ronco Plastics is your best choice IMO. They make top quality tanks for a very reasonable price, have 400 shapes and sizes, over 100 of which are non-rectangular and install fittings in the sizes and locations specified by the customer when they make the tank. They're in Tustin CA.

Ronco Plastics marine Tanks
Ronco Plastics tank drawings

Happy New Year!

--Peggie !

 

[JRC]

ugh!!!

Precisely!

 

[JRC]

GRP
Ronco Plastics is your best choice

--Peggie !

Thank you for your kind response.


GRP can either be polyester based (if it has a gelcoat, it's polyester) or epoxy. Polyester sticks to polyester, but not to epxoy. Epoxy seems to stick to virtually anything.


I don't think Ronco have a Scottish branch, but I fitted a UK made Tek Tanks custom tank in my last boat and it was excellent.


Happy New Year to everyone

 

[HeadMistress]

I mistook your boat make/model for your location. I'm very familiar with TekTanks, have recommended them often and even allowed them to quote from my book in their literature. Had I realized you were not in the US, they are who I would have recommended.


--Peggie

 

[JRC]

Easily done, Peggie, and mostly my fault - there is more than one Campbeltown in the world, so I've amended my profile to add "Scotland". I'm always very grateful for your expert input, no matter where I am!