Head plumbing diagram - pumping out to sea

[4lane]

Hi all! I just bought a new boat and am looking for input on how the plumbing is set up, which I've diagramed below. Here are the three flows I see, but I could use your help answer a question or two to confirm the role of the manual pump.

1. Tank stored waste: from the head, waste flows from the head on the red line to the 3-way. When the 3-way is set in the tank position, waste flows to tank when pumped from head
2. During pump out: pumping out from the deck, waste gets sucked out of the tank on the blue lines.
Question: is the manual pump a one-way, so the pump-out suction is blocked at the end of the green line, and so just sucks from the blue line(s)?
3. Offshore waste dumping
Question: how does this work? Where does the manual pump come into play?

Thank you!

 

[dlochner]

When the deck fitting is sealed, the manual pump will pull from the tank and out the through hull. If the cap is off, then you'll suck air.

When pumping with the manual pump, the Y-valve should be set to off in both directions or to Tank. If it is open to the head, i.e., sea water discharge, the manual pump may push some of its stuff back up into the head.

The vent on the discharge line to the thru-hull is there to prevent back siphoning from the ocean.

The manual pump is should be a diaggphram pump and should only pump one way.

 

[4lane]

So, you're saying the manual pump is to manually pump the tank out to sea via the thruhull; and to do so, you set the 3-Way to off, and manual pumping will draw from the tank through the red line pass through the 3-way to the orange line, and then flow down the purple line and out of the thruhull? I don't see how the waste makes the turn from the orange to purple line at the "T" instead of flowing back up the grey line to the pump.

When the deck fitting is sealed, the manual pump will pull from the tank and out the through hull. If the cap is off, then you'll suck air.

When pumping with the manual pump, the Y-valve should be set to off in both directions or to Tank. If it is open to the head, i.e., sea water discharge, the manual pump may push some of its stuff back up into the head.

The vent on the discharge line to the thru-hull is there to prevent back siphoning from the ocean.

The manual pump is should be a diaggphram pump and should only pump one way.

 

[dlochner]

So, you're saying the manual pump is to manually pump the tank out to sea via the thruhull; and to do so, you set the 3-Way to off, and manual pumping will draw from the tank through the red line pass through the 3-way to the orange line, and then flow down the purple line and out of the thruhull? I don't see how the waste makes the turn from the orange to purple line at the "T" instead of flowing back up the grey line to the pump.

First, I'm making the assumption that the boat is plumbed to let gravity help. The pump will pull the sewage out of the bottom of the tank and towards the T to the thru-hull. It may back up a bit to the Y-Valve, which is why it needs to be closed. Once the hose from the T to Y-valve is full, the sewage will go down to the thru-hull and out to the deep off shore ocean, provided the the seacock at the thru-hull is open. It it is closed the pump will just pressurize the hoses until they are full or bust open.

 

[Scott T-Bird]

In my opinion, this system is over-complicated and prone to problems. Especially since you shouldn't be discharging into the Hudson, you don't need 2 separate paths to discharge overboard. But you do have access to the ocean, so it won't hurt to have one means of overboard discharge into the ocean.

This system appears to be designed so that you can flush the toilet directly into the sea; and, you can pump out the tank into the sea. But you shouldn't really need to do both. I would choose to eliminate the toilet-to-sea path and only provide a means for pumping out the tank into the sea when you are over 3 miles offshore.

I have a few more comments about your diagram. You appear to show a diversion valve (aka "Y-valve") between the toilet and the tank but you label the intake "off". That's not how these valves work. You can't shut off the intake. The intake is always open and the valve simply diverts the flow thru one of the discharge openings, depending on which way you have positioned the lever. If you have some kind of valve that works as you describe (with the ability to "close" the intake) I'll apologize. But that would be highly unusual for this kind of system.

Other comments: There are too many open tees and they are all prone to problems. I wouldn't rely on a manual pump to block backflow or air leakage when pumping out thru the deck fitting. The vent between the thru hull and the open tee will be at a high point to prevent siphoning but I don't think it is typical to use a vent. Usually, this function is provided by a ventilated loop fitting at the high point and there is no need to run a vent hose to the outside of the boat.

Finally, I'll suggest a simplified and more effective system that will provide everything that you need and be far less prone to problems.

1. Read Peggy's book for detailed explanation about your wastewater system and employ her recommendations.

2. Eliminate the y-valve between the toilet and the tank. Just provide a simple discharge line from the toilet to the tank. You don't need to pump your toilet directly overboard. Just pump the black water into the tank.

3. Install a Y valve between the tank discharge hose and the deck pump out fitting. The opposite side of the diversion will go to the pump. The pump will be situated between the y-valve and the thru hull. Your y-valve will normally be set open to the deck fitting because you will normally be emptying your tank via dock pump out or other surface pump out means.

4. On the rare occasion that you manually pump out your tank to the sea, you will then switch the diversion valve over and open the thru hull before pumping.

5. Your thru hull will be closed 100% of the time (except when pumping overboard) so there is no need to have a ventilated loop in this system. But if you think that it would be a good idea to include a ventilated loop, I would place it on the toilet discharge line between the tank and the toilet. This will prevent the toilet from filling up and overflow in the very unlikely event that you leave both the thru hull and the y-valve open to the pump, and water backflows against the pump. But this is so unlikely that I don't find there to be any need on my boat.

6. I would also replace the manual pump with an electric macerator pump, but this adds installation complications. You would have to provide electrical service and probably replace the thru hull to accommodate a smaller diameter discharge hose if the hose in your boat isn't small diameter to begin with. Since the hose is probably sized for the toilet discharge, it is probably 1.5" diameter. My discharge hose from the macerator pump is just 3/4" if I'm not mistaken.

I hope that answers some questions. In short, I wouldn't be happy with your over-complicated system and hodge podge fittings. I would make modifications to make it simplified and more efficient. I would also replace the manual pump with an electric pump to make it less labor-reliant when pumping overboard.

 

[jssailem]

Firstly, one of the best resources you can have on your boat to address the questions of the head and it's plumbing is the book by @Peggie Hall HeadMistress The New Get Rid of Boat Odors

Raritan publishes this diagram in their manual as a design of a system with tank and overboard discharge.

 

[jssailem]

This discussion might be helpful.

Vented Loop

I‘m in the process of replacing the sanitation hoses on my ‘90 Catalina 25 and have discovered that there was no vented loop on the toilet discharge line. These the original hoses. There is a slight uphill run from the toilet to the entry point on the top of the holding tank but the tank and the...

forums.sailboatowners.com

 

[dLj]

In my opinion, this system is over-complicated and prone to problems. Especially since you shouldn't be discharging into the Hudson, you don't need 2 separate paths to discharge overboard. But you do have access to the ocean, so it won't hurt to have one means of overboard discharge into the ocean.

This system appears to be designed so that you can flush the toilet directly into the sea; and, you can pump out the tank into the sea. But you shouldn't really need to do both. I would choose to eliminate the toilet-to-sea path and only provide a means for pumping out the tank into the sea when you are over 3 miles offshore.

The question is really how and where is the boat going to be used. The ability to pump out the tank into the ocean and the ability to directly discharge from the head into the ocean is a pretty standard way of building these systems when a fair amount of time is to be spent outside where direct discharge is permitted.

You start a trip in an area where direct discharge is not permitted - hence you use the holding tank. You head off and you get beyond the no discharge limit, and now you will empty that tank so that when you arrive back inside the no discharge zone, your tank is empty. But while you are out there, you want to directly discharge, you don't want to be filling your tank and them pumping it out. You want that holding tank empty. If you are going to spend any length of time outside the no discharge zone, you want both options. If you are off shore for several days or more - you want direct discharge.

All these standard marine systems are complicated and prone to problems... That's just one reason why I run composting heads - they are the opposite of complicated... (not to mention just how much space is gained...)

dj

 

[Scott T-Bird]

The question is really how and where is the boat going to be used. The ability to pump out the tank into the ocean and the ability to directly discharge from the head into the ocean is a pretty standard way of building these systems when a fair amount of time is to be spent outside where direct discharge is permitted.

29' boat upstream on the Hudson, new boat owner(?) .... my suspicion is that it's not going to be passage making on the Ocean. That's why I figure that there is limited need for discharging the toilet directly overboard. Besides, I've had it both ways. On my first boat, the y-valve was before the tank. My current boat only flushes to the tank and I can now discharge overboard on the ocean at any convenient time. It may be just my preference, but I can tell you that I am much more comfortable flushing into the tank and discharging into the ocean during intervals that are convenient to me. I would much rather have the security of opening the thru hull ONLY when I want to rather than leaving it open simply for the convenience of flushing the toilet. It is a very easy procedure to lift a cushion, divert the y-valve, open the thru hull and pump the tank dry using a convenient on-off switch. It takes less than 5 minutes and if I'm on a passage, it only has to be done perhaps once every 3 days. The thru hull stays closed all that time rather that remaining open continuously to use the toilet.

I don't really like the diagram that @jssailem posts. First, the sanitation device looks more complicated than necessary. Second, you can't empty the tank when off shore. Emptying off shore when you have access to the ocean is far more convenient than finding a pump out facility in some locations. What do you do when your tank is full and you can't find a pump out facility? All it takes is a macerator pump, which works splendidly for emptying out the tank when you are offshore.

 

[dLj]

29' boat upstream on the Hudson, new boat owner(?) .... my suspicion is that it's not going to be passage making on the Ocean. That's why I figure that there is limited need for discharging the toilet directly overboard. Besides, I've had it both ways. On my first boat, the y-valve was before the tank. My current boat only flushes to the tank and I can now discharge overboard on the ocean at any convenient time. It may be just my preference, but I can tell you that I am much more comfortable flushing into the tank and discharging into the ocean during intervals that are convenient to me. I would much rather have the security of opening the thru hull ONLY when I want to rather than leaving it open simply for the convenience of flushing the toilet. It is a very easy procedure to lift a cushion, divert the y-valve, open the thru hull and pump the tank dry using a convenient on-off switch. It takes less than 5 minutes and if I'm on a passage, it only has to be done perhaps once every 3 days. The thru hull stays closed all that time rather that remaining open continuously to use the toilet.

I don't really like the diagram that @jssailem posts. First, the sanitation device looks more complicated than necessary. Second, you can't empty the tank when off shore. Emptying off shore when you have access to the ocean is far more convenient than finding a pump out facility in some locations. What do you do when your tank is full and you can't find a pump out facility? All it takes is a macerator pump, which works splendidly for emptying out the tank when you are offshore.

The main question the OP asked was about the use of the manual pump - I was more trying to illuminate the how and why... I'm not going to redesign his system unless he asks...

dj

 

[Peggie Hall HeadMistress]

Why are there 6 90s in the red line?

Firstly, one of the best resources you can have on your boat to address the questions of the head and it's plumbing is the book by @Peggie Hall HeadMistress The New Get Rid of Boat Odors

Thanks for book plug!
That title (my publisher's idea) is a bit misleading because although it does address every source of odor on a boat, their causes and cures, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that includes US marine sanitation regs, almost every make/model manual and electric toilet and other equipment, holding tank plumbing and maintenance....iow just about everything you need to know to have trouble free, odor free boat. And since no book can ever include all the answers to every boat owner's questions, I hang out here to try to answer the ones it doesn't.

--Peggie

 

[colemj]

The question is really how and where is the boat going to be used. The ability to pump out the tank into the ocean and the ability to directly discharge from the head into the ocean is a pretty standard way of building these systems when a fair amount of time is to be spent outside where direct discharge is permitted.

You start a trip in an area where direct discharge is not permitted - hence you use the holding tank. You head off and you get beyond the no discharge limit, and now you will empty that tank so that when you arrive back inside the no discharge zone, your tank is empty. But while you are out there, you want to directly discharge, you don't want to be filling your tank and them pumping it out. You want that holding tank empty. If you are going to spend any length of time outside the no discharge zone, you want both options. If you are off shore for several days or more - you want direct discharge.

I'm with dLj on this. Yes, one could use the tank and then pump it out offshore in areas that don't have pumpout facilities, but that is not always the case. The worse thing in an anchorage is somebody emptying their entire holding tank at once because they are full and the weather isn't conducive to leaving, or they are just too lazy to put everything away and get the boat ready for sea. Single random flushes in anchorages are unnoticeable, but an entire tank turns the water brown and smelly.

Even offshore for several days, you do not want to be messing with holding tanks and pumping them out. Direct discharge also removes any odor issues and tank buildup, and decreases potential for clogging.

If the OP wants an electric discharge pump, don't get a macerator type. Those are awful and hardly fit for purpose, and will be the largest killjoy on your boat. Get an electric diaphram type of pump like the Whale 320 waste. Less expensive, and you can just forget about it.

The OP's system is a bit strange because it is attempting to use a single thruhull for two purposes, thus relying on more fragile stuff like a pump's check valve preventing flow from going the wrong way, and getting all valves positioned correctly. I don't understand that one vented loop.

Some 3-way valves do have an off position. Ours do.

Mark

 

[4lane]

Thank you all for your comments. But a lot of assumptions going on here. I'm not going to change the system so I don't need advice on what to modify, it's a factory install that is very nicely done so it's not some hack-job someone added, yes it's plumbed for the toilet and the tank to manually pump out, I do go out in the ocean if you must know, the diagram is indicative and not an exact replication of # of turns in lines (tubing can't make 90's), the 3-Way has a mark of "OFF" on it, etc., etc.

What I did get from your comments though, is that this system is maybe a bit overengineered. And that is exactly the point of my question. I was trying to wrap my head around how two specific flows worked - the answers were not obvious given that:

A) question #2: pumping out from the deck goes to a 'T', so what happens in that scenario
- answer seems to be the manual pump blocks the pump out suction, forcing the suction to just follow the blue lines to tank
B) question #3: using the manual pump also engages a 'T', so what happens when the waste meets that point
- answer seems to be that when manually pumped, waste will go up the grey line, but will eventually flow out the purple line to the seacock.

 

[Peggie Hall HeadMistress]

B) question #3: using the manual pump also engages a 'T', so what happens when the waste meets that point.
- answer seems to be that when manually pumped, waste will go up the grey line, but will eventually flow out the purple line to the seacock.

The answer should be: a wye valve instead of a tee.

And fwiw, boat boat builders are the WORST sanitation plumbers on the planet...they don't design systems, they just throw them together the easiest, cheapest (keeping in mind that labor is a major part of the cost) way.

--Peggie

 

[dLj]

Thank you all for your comments. But a lot of assumptions going on here. I'm not going to change the system so I don't need advice on what to modify, it's a factory install that is very nicely done so it's not some hack-job someone added, yes it's plumbed for the toilet and the tank to manually pump out, I do go out in the ocean if you must know, the diagram is indicative and not an exact replication of # of turns in lines (tubing can't make 90's), the 3-Way has a mark of "OFF" on it, etc., etc.

What I did get from your comments though, is that this system is maybe a bit overengineered. And that is exactly the point of my question. I was trying to wrap my head around how two specific flows worked - the answers were not obvious given that:

A) question #2: pumping out from the deck goes to a 'T', so what happens in that scenario
- answer seems to be the manual pump blocks the pump out suction, forcing the suction to just follow the blue lines to tank
B) question #3: using the manual pump also engages a 'T', so what happens when the waste meets that point
- answer seems to be that when manually pumped, waste will go up the grey line, but will eventually flow out the purple line to the seacock.

I wouldn't say it's over engineered - I'd say it's a commonly found system for both near and off-shore usage.

With all our rambling - you have answered those two questions correctly....

dj

 

[4lane]

Thank you!

I wouldn't say it's over engineered - I'd say it's a commonly found system for both near and off-shore usage.

With all our rambling - you have answered those two questions correctly....

dj

 

[Scott T-Bird]

Leaving system as is, I would be inclined to replace the open T between the deck and the pump with a diversion valve. Thus, you wouldn't be relying on the pump to preserve suction & it would provide a means for lock-out to prevent fines from a snooping inspector. I suppose you may have a lock on the thru hull, but then again, you may not.

Questions often elicit freely given advice. No offense intended or taken!

 

[dLj]

Leaving system as is, I would be inclined to replace the open T between the deck and the pump with a diversion valve. Thus, you wouldn't be relying on the pump to preserve suction & it would provide a means for lock-out to prevent fines from a snooping inspector. I suppose you may have a lock on the thru hull, but then again, you may not.

I really don't think the OP needs to change anything in his system.

dj