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Discussion Starter #1 (Edited)
Hello everyone

I am replumbing my 10 years old boat (IP 37) and want to get some advise and ideas.
I removed the old head, the aluminum holding tank and all the hoses yesterday. The new system will have a LaVac head with the MK5 manual pump and a Sealand HTS plastic holding tank. The hose is trident #140 odor shield.
I will install a seperate MK5 manual pump after the holdingtank for discharge to the thru-hull.

I have some questions about routing the waste hoses especially about combining the "direct from the head" and the "from the holding tank" outlets. I will install a diverter valve (Jabsco) after the head to direkt the flow either to the thru-hull or into the holding tank. So far so good. The holding tank has a seperate pickup for the pump-out so that get's connected directly.

My question is about the 2nd pickup from the holidng tank to the thruhull: Of course I will run a siphon break loop after the holding tank. WOuld I need another divider valve to connect the hose to the thru-hull to combine it with the hose coming directly from the head or is it sufficient to have just a Y plumbed?

I hope the description is clear enough. If not I can try to rephrase.



Thanks for all and any inputs.
 

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A better solution would be to route all waste through the holding tank. No diverter is needed, just a T. From the T one line goes to the pump then to the through hull (no vented loop needed-it would just vent the holding tank to interior of boat!) and the other to the deck pumpout. When pumping out offshore you open the through hull. At all other times it is closed which allows the deck pumpout to pull from the tank.An anti
siphon loop is necessary on the inlet to head. The outlet will loop up to the pump and then back down to holding tank. At the top of the inlet loop install one of the two air bleed valves supplied by Lavac. One has a larger hole (the black one). The hole size determines the amount of water left in the bowl after pumping - larger the hole, less water in bowl. The white one is recommended for installation on or above the waterline, the black one for below waterline. The holding tank will vent to outside , probably high on hull side where the last tank vented.
 

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The above system is the simplest most trouble free way to plumb a holding tank. No diverter valve to stick and less connections to possibly leak. Also with all waste going through the holding tank, there is a lot less chance of it settling out and hardening as does a seldom used tank. I am surprised that IP
used aluminum as corrosion from waste is a problem.
 

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Discussion Starter #4
mitiempo:
Thanks for your reply. While I do agree in principal this is not applicable in my case. With the tank being below water level all the contents would needed to be pumped twice (head to tank - tank to thruhull) I personally prefer a direct line head to thruhull for all the times outside the Mile coastal area.

Thanks
 

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Don't you mean - THREE MILE LIMIT???

mitiempo:
I personally prefer a direct line head to thruhull for all the times outside the Mile coastal area.


The three mile offshore limit applies to the entire coastline - east/west/south etc. Wondering where you come up with the 1 mile?
 

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I am certainly no expert on this stuff but I have been looking into different plumbing solutions as I recently purchased a boat that will need some new plumbing possibly.

In Don Casey's articles he states that if the head is below waterline then you need a vented loop in at least the discharge from the head to through hull. He states you can do without the vented loop in the intake and he gives reasons for stating that.

I assume there is a way to vent your vented loop that is on the discharge to the outside, maybe combine it with a tee into your tank vent?

Installing a Head by Don Casey

Volkhard, check out the link he shows how to hook up both a direct discharge and both deck and through hull pumpout of the tank.
 

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Volkhard—

While it is true you'd have to pump the waste out of the tank, the real advantage of plumbing the head with no direct discharge is that it simplifies the plumbing and reduces the number of hoses in which waste can sit and permeate the hoses.

Your setup will also require TWO VENTED LOOPS, one for the holding tank discharge line and one for the head discharge line, unless you put the vented loop after the Mk V diaphragm pump, in which case the pump and most of the line up to the vent will have waste sitting for long periods of time and increase the probability of problems with the pump clogging.

If you put the vented loops on each line, then you'll have a lot of hose that has waste sitting in it.
 

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sailingdog

why is a vented loop required between the holding tank & the through-hull - I've never seen this recommendation before and can't understand why it's necessary if the through-hull is closed when not pumping out as it should be?

Drlove

I think casey is wrong - you ALWAYS want a vented loop in the intake in my opinion
 

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Some people leave the seacocks on their boats open, regardless of whether they should be or not. :) If you close the through hull regularly, then the vented loop probably isn't necessary. :)
sailingdog

why is a vented loop required between the holding tank & the through-hull - I've never seen this recommendation before and can't understand why it's necessary if the through-hull is closed when not pumping out as it should be?

Drlove

I think casey is wrong - you ALWAYS want a vented loop in the intake in my opinion
 

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Discussion Starter #10
to jimq 26 :

Of course it is the 3 mile limit! I am aware of it and obey it. When I wrote the reply my num/lock on my keyboard must have been off and after spell checking it posted right away. YES within 3 miles AND in any no discharge zone everything needs to go into the tank.

to everybody:

I am planning 2 vented loops for the discharge side and a kind of vented loop (pinhole in a looped supply-line with the fitting that came with the LaVac head). My layout has the MK5 pumps just underneath and before the vented loops to minimize the amount of effluent sitting there. From the loops everything will be plumbed to be downhill going either to the holding tank or to the thruhull. I believe my plumbing scheme is okay so far. The real question was the point were the discharge line from the holding tank meets the direct discharge from the head both (with vented loops above sea-level!) meet just in front of the thruhull: diverter valve or just Y hose connector?
 

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Volkhard-

I'd just go with a y-connector there... AFAICT, there's no need for a diverter valve.
 

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I installed a lavac last year, with one y-valve (to pump overboard or to the holding tank), and another to select whether the hand pump pumps waste from the toilet, or from the holding tank (to empty tank when out past 3 miles). there is actuallly a 3rd y valve installed on the top of the holding tank, wheer you choose to direct the waste toward the lavac pump - overboard, or to the deck pump out.

Although it seems complicated, it does allow for a lot of flexiblilty.

One comment on the suggestion to direct all waste to the holding tank. We often sail a mile or so from shore, and the direct overboard allows the girls to pee, without filling up the holding tank (quickly). Guys can use it too, or piss overboard, just cause they can! If someone needs to use it for more than that, they switch the y-valve to tank and then back to overboard.

Then we have the option to pump out later at the marina, or discharge past 3 miles. With the flush water, you will fill a tank quite quickly if you use it for al the beer induced peeing.
Since we have washrooms at the marina, we don't use the head much at the dock.

The only downside to the extra valves is extra hose to connect them all, which takes more water to flush clean.
 

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You are aware that using the head and discharging the water and PEE overboard within the three mile limit is illegal, and if you're caught doing so, can get hit with nasty fines... The law is written specifically forbidding any marine sanitary equipment discharging overboard within the three-mile limit—this includes the head or even a bucket or bottle you piss in... However, pissing directly overboard is legal, since it doesn't use any marine sanitary equipment... it doesn't violate the law.

One comment on the suggestion to direct all waste to the holding tank. We often sail a mile or so from shore, and the direct overboard allows the girls to pee, without filling up the holding tank (quickly). Guys can use it too, or piss overboard, just cause they can! If someone needs to use it for more than that, they switch the y-valve to tank and then back to overboard.
 

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Very interesting indeed. This is going to help me a lot (I hope)

My last boat had plumbing (which I installed so I have no one to blame but me) that made a nuclear reactor look simple.

  1. Head went to a "Y" valve. One side to thru hull, other side to holding tank.
  2. Holding thank had one in (from head) and four out.
    1. Two vents (as per Peggy Hall)
    2. one to pump out and
    3. one to a macerator pump.
  3. Macerator pump went to thru hull (controlled by another "Y" valve.)
It worked very well. I had room to do it and I was pleased. :)

My new boat currently has a "Y" valve at the head - one side to tank that has one vent, one side to thru hull through a vented loop. No way to empty the tank except via a pump out.

The tank is very close (2 feet) to the thru hull. I was going to do the two "Y" valves and a macerator pump like the old boat. But reading these posts, maybe I can:

  1. go from head to holding tank
  2. tank to a "Y" valve
  1. one side to pump out
  2. other side through a macerator then through the vented loop to the thru hull

I sure like the "everything goes through the tank and keeps it flushed and not built up" theory.

What am I missing??? Comments, suggestions?

Many thanks
 

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Before going to all that trouble, consider a composting toilet. I put one in last summer and love it and will have no other on any boat I own in the future. I cheerfully dumped my smelly holding tank, hoses, pumps, valves etc. Now I have a simple head, the only moving part on it is a solar vent fan, no smells, no holes (I plan to remove and seal the 1 1/2 thruhull and should the CG come aboard to inspect the boat I will be in total compliance. I also gained the space where the holding tank used to be.

Take a look on the AirHead or Nature's Head websites (there are also a couple of other companies making composting toilets) for more info. I love mine and feel that it is the wave of the future.
 

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  1. go from head to holding tank
  2. tank to a "Y" valve
  1. one side to pump out
  2. other side through a macerator then through the vented loop to the thru hull
I sure like the "everything goes through the tank and keeps it flushed and not built up" theory.

What am I missing??? Comments, suggestions?

Many thanks
This is probably your best bet. I'd use a diverter valve rather than just a "Y" on the pumpout hose. And, I'd use a manual diaphragm pump, rather than a macerator. The reason for the diverter is to prevent the deck pumpout fitting from trying to pull stuff through the diaphragm pump or macerator, especially if you've accidentally left the seacock open. ;) The reason for the diaphragm pump rather than the macerator is that you can save electricity and even if your batteries are dead, you can still pump out the holding tank.

BTW, that's basically how the head on my boat is plumbed. Head ->holding tank. Holding tank to y-valve. y-valve to either deck or diaphragm pump/seacock/through-hull.
 

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Discussion Starter #18
To all:

I just added a drawing to my original post. This should clarify things.
I agree with sailingdog in regard to the diaphragm pumps. My scheme uses 2: one above the head (came with the LaVac head) and a second one above the holding tank for discharge.

BTW: the holding tank features a second pickup so the pump out /thrudeck has its own connection to the tank and doesn't need a valve .

The whole waste system will than be non-electric (besides the tank monitor ....)
 

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Manual is the better way to go with heads and plumbing on a boat... if you can get away with it... I've seen too many horror stories with macerator pumps and electric heads.. :)
 
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