Confusing plumbing configuration -- thoughts?

CLucas · #1 (**permalink**) 12-29-2008

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.

sailingdog · #2 (**permalink**) 12-30-2008

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.

xort · #3 (**permalink**) 12-30-2008

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.

bubb2 · #4 (**permalink**) 12-30-2008

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.

CLucas · #5 (**permalink**) 12-30-2008

Quote:

Originally Posted by sailingdog

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."

Quote:

Originally Posted by sailingdog

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...)

Quote:

Originally Posted by sailingdog

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.

Quote:

Originally Posted by sailingdog

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...)

Quote:

Originally Posted by sailingdog

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.

CLucas · #6 (**permalink**) 12-30-2008

Quote:

Originally Posted by bubb2

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!

xort · #7 (**permalink**) 12-30-2008

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.

bubb2 · #8 (**permalink**) 12-30-2008

offshore you pump it with the macerator. then flip the y-valve it fills a little until it is even with the water line. leave slosh around for a while and pump again. Just a thought!

CLucas · #9 (**permalink**) 12-30-2008

Quote:

Originally Posted by xort

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.

sailingdog · #10 (**permalink**) 12-30-2008

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