[UltimateWalrus]

I could use advice from people who know about holding tank systems.

I'm aiming to install a new holding tank system from scratch. For whatever reason my 1976 Ericson 29 does not have one and does not appear to ever have had one... just two thru-hulls, one for intake and one for output.

I've done hours and hours of research and come up with this diagram of the waste system I intend to implement:

I think it should be OK, provided I can get everything to fit together and muster up the courage to buy 100's of dollars of components and drill a couple above-waterline holes through my hull. Though if anyone has any feedback or suggestions on how I am approaching this I'd be glad to hear it.

My biggest confusion right now is coming from how I'm supposed to connect the vented loop to the vent line. I'm planning on trying to use 1.5" sanitation hose for everything (including the vent line, which as I understand it, is better off thick to allow the holding tank more oxygen). However, the biggest hose any vented loop will accept on its vent is 1/2" as far as I can find, and the cheap one I would prefer to buy, has a measly 1/4" port with its adapter.

On top of that, it states that the valve has to be removed to insert the adapter. I researched and found that if you attach to a vent line, the loops are more reliable without the valve anyway. This is all fine and good, except that as far as I can tell there will now be sewage splashing up into the vent line every time I pump the head. This means, if I don't want to deal with terrible smells, I have to somehow find a 1/4" ID marine sanitation hose (which I can't find anywhere), AND adapt it to a tee connector on the 1-1/2" marine sanitation hose I plan on using for the vent.

I cannot find an adaptor anywhere that will let me adapt a 1/4" hose to 1 1/2", much less one designed for sewage. I can't even find a combination of adapters that would work; the closest I could get is this tee connector, and it's still three times too big.

Did part manufacturers as a whole really overlook a standard, widespread head configuration, or am I just blind, crazy and overthinking things (I suspect the latter)?

 

[Gladrags1]

I must admit to never being aware that one could attach a hose to a vented loop vent. It just vents locally and the valve always keeps the effluent inside the hose where it belongs. There never has been any smells either so I really don't see the need to connect it to a vent.

You schematic looks ok, gives you all possible discharge options. You can go online to West Marine Advisors and check their schematics about usual setups. You're using 1-1/2" hose for vent is double the customary size of 3/4". Can you find a deck fitting for that? Yes, it will bring in more oxygen which is good but I wonder if it is overkill.

On sailboatowners.com forum there is a forum dedicated to heads and such. Peggy Hall (calls herself the "Headmistress ) is the resident expert there. You might want to pose your question on that site as well to get her response.

Tod

 

[Minnewaska]

Vented loops of all sizes are available

Marine Vented Loops on Sale

1.5" vents are pretty big, despite the accurate advice to oversize them. Actually you would be much better off with 2 one inch vents on either side of the tank.

The only thing I would not do in your set up is drain from the bottom of the tank. I prefer a dip tube that draws from the top, via deck pump out or mascerating pump. Having no bottom fittings reduces a point of failure. A nasty failure. However, there is an advantage to being able to discharge by gravity in open water and not having to power or buy a mascerating pump.

 

[jimjazzdad]

I have a vented loop on the head discharge (as well as the seawater inlet to the head). Just using the built-in check valve - no connection to holding tank vent. Never had any problem with leakage or odor.

 

[bvander66]

Getting pretty complicated. Y valves are a common blockage spot in black water systems,
I have two discharges in holding tank, one for pump out, other for overboard, that would eliminate one and simplify that side.
try to avoid y valves below holding tank, even the best will permeate smell of black water sits in it continually.

 

[svHyLyte]

I could use advice from people who know about holding tank systems.

I'm aiming to install a new holding tank system from scratch. For whatever reason my 1976 Ericson 29 does not have one and does not appear to ever have had one... just two thru-hulls, one for intake and one for output.

I've done hours and hours of research and come up with this diagram of the waste system I intend to implement:

I think it should be OK, provided I can get everything to fit together and muster up the courage to buy 100's of dollars of components and drill a couple above-waterline holes through my hull. Though if anyone has any feedback or suggestions on how I am approaching this I'd be glad to hear it.

My biggest confusion right now is coming from how I'm supposed to connect the vented loop to the vent line. I'm planning on trying to use 1.5" sanitation hose for everything (including the vent line, which as I understand it, is better off thick to allow the holding tank more oxygen). However, the biggest hose any vented loop will accept on its vent is 1/2" as far as I can find, and the cheap one I would prefer to buy, has a measly 1/4" port with its adapter.

On top of that, it states that the valve has to be removed to insert the adapter. I researched and found that if you attach to a vent line, the loops are more reliable without the valve anyway. This is all fine and good, except that as far as I can tell there will now be sewage splashing up into the vent line every time I pump the head. This means, if I don't want to deal with terrible smells, I have to somehow find a 1/4" ID marine sanitation hose (which I can't find anywhere), AND adapt it to a tee connector on the 1-1/2" marine sanitation hose I plan on using for the vent.

I cannot find an adaptor anywhere that will let me adapt a 1/4" hose to 1 1/2", much less one designed for sewage. I can't even find a combination of adapters that would work; the closest I could get is this tee connector, and it's still three times too big.

Did part manufacturers as a whole really overlook a standard, widespread head configuration, or am I just blind, crazy and overthinking things (I suspect the latter)?

You are over thinking things. There is no need to connect the vent on the "anti-siphon loop" to the vent from the holding tank. The "duck bill" valve in the vent is designed such that neither water nor air can pass the vent, out of the loop. It will only open to admit air into the loop when there is "suction" set up by a siphoning effect. That is why one must "push" effluent through the loop with one's pump rather than attempting to "pull" it through.

The following is a somewhat clearer illustration of your arrangement:

This arrangement, however, relies on two Y-Valves which can be problematic unless they are exercised routinely. Note, too, that one would always want to maintain the deck pump-out/through-hull selector Y-valve in the deck position against the possibility of a back-flow valve failure/leakage in the holding tank pump (it does happen!).

FWIW...

 

[CLOSECALL]

Get an airhead. 1,000 dollars and a one hour install and you are on your way. Get rid of the thruhulls.

 

[MarkofSeaLife]

You are over thinking things. There is no need to connect the vent on the "anti-siphon loop" to the vent from the holding tank.

FWIW...

I agree with Mr FWIW, however not to the fullest extent... Why does one need an anti siphon loop?
Some installations need it, some dont.

Work out if yours does. I don't know, but I know my 2 heads don't have any. Must be a reason.

Mark

 

[UltimateWalrus]

Thank you all for your suggestions! Keeping all valves above the tank level and using a diptube definitely seem like smart ideas, and I guess I could probably just wait until if and when the vented loop becomes a problem to connect it to the vent.

Get an airhead. 1,000 dollars and a one hour install and you are on your way. Get rid of the thruhulls.

This looks very cool! I had heard of composting toilets but I guess I hadn't realized how robust they could be. Two people for a month is pretty impressive... and there's nothing to stop me from just dumping the compost overboard when I'm three miles out.

The more I think about it, the more "onboard" this idea I am. I can think of many advantages of this toilet over my planned system:

-Easier to set up
-Less complex, meaning less points of failure, less maintenance, and less chance of a terrible smell I can't find the exact cause of
-Totally self-contained and easy to service or replace if needed
-More sanitary. Don't have to have raw sewage sloshing around in my boat, just dried out sewage jerky
-Seems sanitary enough that I could actually use it in the marina. If I had a holding tank, I wouldn't want to use it unless I have to (if there is no bathroom onshore)
-I DON'T HAVE TO DRILL HOLES THROUGH MY HULL!
-The dead seawater sulphur smell will be a thing of the past, if it's waterless
-I can close one or even both of the thru-hulls. That's one less way my boat can sink (or stink)

Are there any disadvantages to this system? I can think of a few:

-Requires a small fan to be constantly running, draining the battery.
-Slightly more expensive. But really, if you add the ~$700 it was probably going to cost me for holding tank parts to the many hours it would take to install, time * money equals out to be about the same if not a little better.
-Have to buy paper bowl liners. This isn't necessary for the composting to work as far as I can tell, but makes the waterless operation more sanitary.

Overall it seems almost too good to be true, but I'm thinking I will probably give Air Head a go, once I can verify it will fit where the old toilet stands. I'm glad I asked! Thank you CLOSECALL!

 

[Capt Len]

If the top of the toilet is close to the waterline it 's discharge and inlet should both be vented.(separate from tank vent) Early morning dipping of private parts will tell you wheather it's needed.

 

[CLOSECALL]

Glad if I could help. We have a 30 foot Pearson and the composter fit easily.

There are at least four of these units on boats at our dock and none of the owners are ever fixing them. There are several threads here that will give you plenty of thoughts on the topic. Very few negative comments from actual owners.

Be advised, they ain't for everybody.

 

[mitiempo]

There is really no reason for any "Y" valve in a head system. The simpler solution is from head to tank to a "T", one side of which goes to the deck fitting and the other to the macerator and through hull. When using the macerator the deck fitting is closed and when pumping out through the deck fitting the through hull is closed.

Using the tank all the time keeps the waste less likely to turn into cement in the corners.

If a gravity draining holding tank works out in the installation it is the best idea.

There should be 2 vents of 5/8" or 3/4", one on each side of the boat.

Composting heads are another argument.

 

[UltimateWalrus]

Glad if I could help. We have a 30 foot Pearson and the composter fit easily.

There are at least four of these units on boats at our dock and none of the owners are ever fixing them. There are several threads here that will give you plenty of thoughts on the topic. Very few negative comments from actual owners.

Be advised, they ain't for everybody.

They still sound great to me. I imagine if I had someone else to maintain the boat for me, a holding tank might be a little more seamless, but as someone who does their own maintenance, I can definitely say that a closed system with dried dung sounds a lot more appealing than sprawling, complex plumbing with raw sewage.

Mitiempo made a good point about using the tank all the time. I had thought I simply wouldn't use the holding tank when docked at a slip, using the thru-hull for #1 (I'm aware this is against regulation but am convinced it's harmless) and the onshore bathroom for going #2. But if you're not using the tank constantly I guess it can form harmful sediments... in which case the valve before the tank might not be so great. I also heard about cross-venting but wasn't sure if it'd be worth it to route another vent all the way through the stern of my boat.

Of course, if I get an Air Head, it's easy enough to comply with the regulations 100%. It's almost like a more hygienic piss jug (a solution employed by my neighbor down the way). When the liquid compartment gets full, I can just take it onshore and dump it in a toilet.

 

[ggray]

I think if the top of the bowl is less than than 6 inches (may be more than that) above the waterline --when heeled, if applicable-- you need vented loops on intake and discharge to the sea.

I removed a lot of plumbing to simplify. The head discharge goes straight to holding tank, no Y-valve.

 

[UltimateWalrus]

I think the top of my bowl is around six inches above the waterline when perfectly level, so a vented loop would definitely be necessary unless I tried to do a gravity discharge, but the only way to do that on my boat would be to take out a sink to make room for a big ugly holding tank.

 

[Stu Jackson]

Boy, are you ever overthinking this.

And reinventing the wheel.

Try this:

Selecting a Sanitation System | West Marine

I dislike their final solution in the big picture at the bottom, because everything has to go to the holding tank.

Our system is simpler: either into holding tank or overboard. Pump out or macerator pump from tank. Simple.

Vented loop between the head hand pump and the bowl, NOT on the intake line from the seacock to the head hand pump.

Vented loop is optional between the head output and the tank, we don't have one, been working fine for 16 years.

Treat the holding tank with Odorlos - Google it.

 

[svHyLyte]

I agree with Mr FWIW, however not to the fullest extent... Why does one need an anti siphon loop?
Some installations need it, some dont.

Work out if yours does. I don't know, but I know my 2 heads don't have any. Must be a reason.

Mark

Mark--The head on a 1970's era Ericson 29 will definitely be below the waterline when on the leeward side when the yacht is hard pressed on that tack unless it is on quite a tall (accordingly inconvenient) pedestal. Accordingly, back siphoning is a possibility and particularly so if there is any wear in the Joker Valve or if the raw-water intake valve is not tight when the "flush" lever is in the Dry Bowl position. (I helped a friend of ours that eschewed an anti-siphon loop bail out his Ericson 29 in Catalina once after a hard pressed beat to the island. From his screaming when he discovered the water above the floor boards once he reached the anchorage, you'd have though he was being murdered!)

 

[RichH]

You are over thinking things. There is no need to connect the vent on the "anti-siphon loop" to the vent from the holding tank. The "duck bill" valve in the vent is designed such that neither water nor air can pass the vent, out of the loop. It will only open to admit air into the loop when there is "suction" set up by a siphoning effect. That is why one must "push" effluent through the loop with one's pump rather than attempting to "pull" it through.

The following is a somewhat clearer illustration of your arrangement:

This arrangement, however, relies on two Y-Valves which can be problematic unless they are exercised routinely. Note, too, that one would always want to maintain the deck pump-out/through-hull selector Y-valve in the deck position against the possibility of a back-flow valve failure/leakage in the holding tank pump (it does happen!).

FWIW...

GOOD DIAGRAM !!!!
Some advocate a 'small' vented loop (the vent valve on the vented loop being 'small') on the inlet to the toilet head line; but, that has to be carefully and accurately sized so that the vacuum generated by the heads manual water pump exceeds the in-rush air leakage of the vented loop - this is to prevent flooding though the toilet in case the toilets dry/wet valve is faulty; if faulty the head will flood into the boat especially if the top of the toilet bowl is below the waterline. The inlet line vented loop height is dependent on how far below the static waterline the toilet is mounted and how far the top of the vented loop is above the static waterline when the boat is well heeled over.

 

[Stu Jackson]

GOOD DIAGRAM !!!!
Some advocate a 'small' vented loop (the vent valve on the vented loop being 'small') on the inlet to the toilet head line; but, that has to be carefully and accurately sized so that the vacuum generated by the heads manual water pump exceeds the in-rush air leakage of the vented loop - this is to prevent flooding though the toilet in case the toilets dry/wet valve is faulty; if faulty the head will flood into the boat especially if the top of the toilet bowl is below the waterline. The inlet line vented loop height is dependent on how far below the static waterline the toilet is mounted and how far the top of the vented loop is above the static waterline when the boat is well heeled over.

It's actually a rather poor diagram.

The macerator should have its own thru hull, because the outlet of the macerator is much smaller than the head outlet.

Therefore, that Y valve isn't needed.

The pump out should have its own connection to the tank.

So, only one Y valve is needed on the head outlet: overboard or to the tank. And you could do it with a simpler ball valve.

This discussion about vented loops is wrong, unless I'm reading it wrong. It's simple: vented loop between the pump on the head and the head bowl. It's a 3/4 inch line with a 3/4" vented loop, nothing to "carefully size" at all. This is required basic stuff and available in ALL head manufacturer's literature for head installation. The heads come with a short piece of white hose between the pump and the bowl. Replace it.

 

[RichH]

Its very simple, If the vent valve on the water inlet to the head allows a greater volume of air than the pump can move water, you will only pump air and not much water to the head/bowl. The air flow through-put of the that vent valve must be sized/selected so that the volumetric flow of air does not reduce what the hydraulic static head requirement to pump water to the bowl. Usually a small fixed diameter orfice is added to the vent valve to control the amount of air flow and still allow enough flow to 'break' any suction that would allow siphoning of water into the boat if that bowl is below the waterline.
Simple hydrostatics.