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Discussion Starter #1
Tackling a project this winter that's been crying out for attention... replacing at least some of the plumbing on my 1977 P30. When I bought her two seasons ago, my surveyor pointed out the puzzling connections shown below. The PO had installed a Y-valve on the intake line that would allow the head to be flushed with the contents of the holding tank (nasty, huh?). Can't understand the reasoning behind this except as a means of introducing as little water into the tank as possible during extended coastal hauls w/o pumpout facilities (??). SD has mentioned this configuration before on a previous boat he owned but I can't find any explanation behind it's purpose -- guessing and hoping he'll chime in :)

This configuration allows for either direct discharge (where allowed) bypassing the holding tank or straight to the holding tank, where it can be emptied either at a pumpout station, or macerated and pumped overboard.

I have several hoses to replace, but am looking for opinions or advice as to whether are ANY redeeming qualities to this layout or if I should just scrap it and start over using a simpler and more traditional layout. Thoughts? Thanks in advance.


 

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CLucas—

I've never seen or had this weird a setup on my boat or any of the ones I've worked on thus far. :) Have no idea why you would want to flush the head using the holding tank contents... EWWW...

The setup on my boat is that you can use the contents of the head SINK to flush the head.... not the holding tank. That allows you to use fresh water rather than salt water to flush the head—which can be better if you're leaving the boat for a while, since it won't have the micro-organisms that salt water has—which eventually die and stink up the head compartment. It also makes it pretty simple to winterize the system.

The simplest setup is usually the best when it comes to the head IMHO. I would recommend that you plumb the head output directly into the holding tank. Then plumb the output of the holding tank to a diverter valve (use the one from the head output that you'll be removing) that leads to either the deck pumpout fitting or the macerator pimp and then to the discharge seacock and through-hull.

The macerator pump should be after the diverter valve, since that will prevent the deck pumpout from pulling waste through the macerator when it isn't operating—which could clog or damage the macerator. It also prevents you from having the macerator pump pushing waste up to the deck pumpout fitting section of the hose and pressurizing it... which can lead to a really nasty surprise to the next person opening the deck fitting. :)

This way, you can empty the holding tank when out past the three-mile limit, or via a pumpout boat/station. You're really not losing much in the way of capability, since any time you'd normally discharge the head directly overboard, you can always discharge the holding tank overboard instead.

You'll probably want a lockable diverter valve, since the authorities prefer to see one that is locked when you're in an NDZ. :)

I hope this helps.
 

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The simple operation would be to remove the y-valve in the head intake line as well as the line from the holding tank to the y-valve and plug the outlet in the holding tank.
Leave the rest alone if it works OK and the hoses are good.
Or do something similar to what dog has. use the y-valve to feed FRESH water to the head and keep the sea water intake for times when you don't have adequate fresh water. I've been contemplating adding a fresh water tank for flushing and feeding it with rain water from the scuppers. Biggest problem is locating a place for the tank.
 

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Discussion Starter #5
I've never seen or had this weird a setup on my boat or any of the ones I've worked on thus far. :) Have no idea why you would want to flush the head using the holding tank contents... EWWW...
...told you it was pretty nasty :) It had my surveyor stumped as well and I guarantee my family would quickly lose any interest in gunkholing around LIS a few days if I told them, "oh, by the way... there's a problem with the head and we need to flush using whatever is in the tank."

The setup on my boat is that you can use the contents of the head SINK to flush the head.... not the holding tank. That allows you to use fresh water rather than salt water to flush the head—which can be better if you're leaving the boat for a while, since it won't have the micro-organisms that salt water has—which eventually die and stink up the head compartment...
Apologies - my bad (and explains why I couldn't find it again...)

The simplest setup is usually the best when it comes to the head IMHO. I would recommend that you plumb the head output directly into the holding tank. Then plumb the output of the holding tank to a diverter valve (use the one from the head output that you'll be removing) that leads to either the deck pumpout fitting or the macerator pimp and then to the discharge seacock and through-hull.
As it is currently set up, it is unnecessarily complicated, which is why I want/need to re-plumb this mess.

The macerator pump should be after the diverter valve, since that will prevent the deck pumpout from pulling waste through the macerator when it isn't operating—which could clog or damage the macerator. It also prevents you from having the macerator pump pushing waste up to the deck pumpout fitting section of the hose and pressurizing it... which can lead to a really nasty surprise to the next person opening the deck fitting. :)
Presently, the tank output is tee'd into the macerator pump rather than going straight in -- can't be very efficient, right? The macerator itself has never functioned which is either the pump itself or the connection (another project...)

This way, you can empty the holding tank when out past the three-mile limit, or via a pumpout boat/station. You're really not losing much in the way of capability, since any time you'd normally discharge the head directly overboard, you can always discharge the holding tank overboard instead.

You'll probably want a lockable diverter valve, since the authorities prefer to see one that is locked when you're in an NDZ. :)

I hope this helps.
Thanks for the fast and detailed reply -- knew I could count on you :) Happy New Year.
 

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Discussion Starter #6
I am wondering if it is plumbed this way as a way to rinse the holding tank after it was pumped. I could see that it would work if the holding tank was below the water line.
Possibly... and you may be onto something. The fitting I have labeled as a vent adjacent to the deck pumpout fitting is threaded (I'll try to get a photo, if I can crawl up that far under the shrinkwrap). Vent at the bow is normal (any reason to have two vents?). Holding tank is below the water line.

Thanks!
 

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2 vents provide air flow thru the tank. Wind enters the at the bow and carries air out the after vent. A very good setup.
 

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Discussion Starter #9
The simple operation would be to remove the y-valve in the head intake line as well as the line from the holding tank to the y-valve and plug the outlet in the holding tank.
Leave the rest alone if it works OK and the hoses are good.
In the evaluation part of it right now. First step was to map out what is there and inspect hoses, etc. A little concerned about what I might find (apart from the obvious...) when I disconnect any hose from the tank to replace it (or plug the outlet). One of those little jobs that turns into something pretty significant -- replacing a hose to replacing the tank and *all* the hoses. At least at the end of the day I'd have a decent system.

Thanks.
 

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Two vents helps keep the tank well aerated, promoting the aerobic, good, non-stinky bacteria, while helping reduce the anaerobic, bad, stinky bacteria. :)
 

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I may be wrong, but it seems to me the output from the tank can lead to a T rather than a diverter. One side of the T leads to the macerator pump and then to a seacock/thruhull. The other side of the T leads to the deck pumpout fitting. When pumping out via macerator, the macerator will suck waste from the tank and not suck air thru the pumpout fitting because the deck fitting will be closed. When waste is being sucked out thru the deck fitting, there shouldn't be any back flow thru the macerator because the seacock will be closed. The diverter valves have been prone to failure in my experience. A T fitting is simpler and more reliable. KISS!
 

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First I wanted to say K.I.S.S.

Many have given the "Keep it simple Simeon" ;)

I just wanted to take a stab at what the previous owner "may" had in mind here. :confused:

This looks to be an attempt at the "Maceration Re-Macerator Flabergastor" :eek:

What I am thinking, where the macerator pumps back toward the head.

This supposed to be manipulated in a way that the pump recirculates the holding tank contents from holding tank and then back into the holding tank! :rolleyes:

This provides a fine chop to the holding tank and maybe additional aeration???

This is just a guess to help provide some insights as to previous owner thoughts.

But, I think some parts may be missing to work correctly.
 

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The main reason I generally recommend using a diverter valve, rather than a Y or T splitter, is that when you're in an NDZ, the authorities will want to see the handle locked to the deck pumpout fitting.

Also, if you have a splitter rather than a diverter valve, and you leave the discharge seacock open when you go to pump out, you'll suction water up through the macerator pump and that may make it take a much longer time to empty your holding tank as well as damage the macerator pump.

The diverter valve also makes it less likely that you'll siphon water through an open seacock back into the holding tank.

I may be wrong, but it seems to me the output from the tank can lead to a T rather than a diverter. One side of the T leads to the macerator pump and then to a seacock/thruhull. The other side of the T leads to the deck pumpout fitting. When pumping out via macerator, the macerator will suck waste from the tank and not suck air thru the pumpout fitting because the deck fitting will be closed. When waste is being sucked out thru the deck fitting, there shouldn't be any back flow thru the macerator because the seacock will be closed. The diverter valves have been prone to failure in my experience. A T fitting is simpler and more reliable. KISS!
 

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Am I not OK with the authorities as long as I locked the waste-out seacock handle? The rest has to do with diligence.
 

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That should do the trick too...
Am I not OK with the authorities as long as I locked the waste-out seacock handle? The rest has to do with diligence.
 

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I am wondering if it is plumbed this way as a way to rinse the holding tank after it was pumped. I could see that it would work if the holding tank was below the water line.
I agree, looks like a way to flush the holding tank either offshore or at the pumpout
 

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I agree with Sailingdog - head direct to tank, tank out to a Y-valve to either the deck or the discharge pump which goes overboard.

I wonder if the pump is attached to the discharge leg of the current setup, rather than the head leg. If it were, and the Y valve was set for head to tank, the pump would be set up to go overboard.

I cruise on Canada's West Coast, where overboard discharge is still allowed except in specific areas, and the advantage of always sending waste to the holding tank is that I can pick when and where I discharge the tank, which allows me to avoid sensitive areas and spread my impact over a larger volume of water.
 

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I love the macerator being set up to push INTO the head, and the option to have the holding tank used as a water SUPPLY for the head.

Surely, that's an April Fools diagram?
 

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I know this is academic since you are rebuilding the system, but I had another thought. Perhaps the PO set this up to empty holding tank. With the system as I understand it you could use the head pump as an overboard discharge device if the macerater pump failed. By flushing the head with the holding tank contents and the discharge seacock open you could bypass a failed direct over board discharge system. This would be nasty, but would be a way to empty the holding tank if all else failed. I am not saying pumping raw sewage open to the cabin via the head bowl is a good idea, but it might work.
 

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Discussion Starter #20 (Edited)
I love the macerator being set up to push INTO the head, and the option to have the holding tank used as a water SUPPLY for the head.

Surely, that's an April Fools diagram?
Wish it were, but I assure you it's no joke. With the diverter on the discharge leg set to the discharge thru-hull, waste is pumped overboard -- with the valve set to the tank, then it's effectively a closed loop. Holding tank as a water supply to the head is gross, but as some have suggested, could be used to rinse the tank after a pump-out.

This is effectively going to be a do-over, and something to thank the PO for (that and the half-filled holding tank -- nice touch).
 
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