Holding Tank

Harry Babb · Post by **Harry Babb** » Jul 30th, '07, 21:35

I am getting very close to putting the "Head" back in DeNada and installing a holding tank.

What size holding tank do you guys recommend installing in our 31's???

Harry Babb

Rawleigh · Post by **Rawleigh** » Jul 30th, '07, 21:53

That depends on whether you are really going to use it or not!

nic · Post by **nic** » Jul 31st, '07, 00:17

Harry,

Just putting one in and have opted for 96 litres which I figure is 25 US gal. Was told that is an OK minimum size by the supplier. We built a custom tank on top of the fuel tank under the aft deck.

Nic

thereheis · Post by **thereheis** » Jul 31st, '07, 02:32

i was going to use a 3 gal.tank but opt otherwise.if you need one let me knoew 3 gal ,i think would be ok ..i still have mine it's new an in the box,,,

phil

IRGuy · Post by **IRGuy** » Jul 31st, '07, 07:22

When I was designing a holding tank system for "Phoenix" to replace the dead LectroSan unit I asked several boater friends about what size I should install. The guys who fished and boated mostly with their buddies almost unanimously said less than 12-15 gal, several less than 10 gal. The guys who had wives and daughters aboard often said at least 25-30 gal., and two said as large as possible. It depends as well on where you use your boat.. if you are in harbors and confined waters a lot I would opt for the largest size I had space for.. if you are out a lot and can empty your tank at sea and pump your head directly overboard you can go smaller.

I read up on installations.. was surprised to read that the vent size is a key to REDUCING odors.. aerobic (with oxygen) decomposition of the tank contents produces less nasty smelling gasses than anaerobic (the absence of oxygen) decomposition does. If you install a tiny (ie: half inch) vent you won't let enough oxygen get into the tank to aerobically decompose the contents and the gasses in the tank will be more odorous.. (plus there is a much greater chance of plugging a small vent in case you overflow your tank, which you will probably do one day!) If you install a larger vent air and oxygen can get into the tank and allow for less odor due to aerobic decomposition. I actually had my tank fabricated with all 1 1/2" fittings and an 8" dia inspection port. When I installed it I actually ran an 1 1/2" vent line to my through hull fitting. I can always bush it down if I want to later, but I can't make it larger. So far so good.

Not a pleasant subject to talk about.. but a very important one if things fail and you need to rip things apart in the future. I have a schematic of my installation.. if you want a copy drop me an email.

Rawleigh · Post by **Rawleigh** » Jul 31st, '07, 10:52

If that is the case, how about two midsize vents, one at each end of the tank, so it can cross ventilate?

IRGuy · Post by **IRGuy** » Jul 31st, '07, 11:24

Rawleigh...

You are correct! That was one of the suggestions I read somewhere.. the more fresh air the better. In my case I did not want to run another hose and make another hole in the boat, but if it is easy to do it does help apparently.

Somewhere I read that it is even better to locate one vent on one side of the boat, and the second on the other side, to take advantage of any differential pressures across the two vents.

algillen · Post by **algillen** » Jul 31st, '07, 11:47

Another way to reduce odor.... plumb your toilet to pull its water from the FW tank, rather than use the sea water pickup. Can't give a chemical engineer's explanation for why it is better, but know for a fact it helped my boat a whole lot.

Kevin · Post by **Kevin** » Jul 31st, '07, 12:21

where do you guys think the best place is to mount the tank? When I was doing my gas to diesel swap I had partially installed one under the cockpit next ot the fuel tank on the port side. Its a 28 though. Ended up taking it out because it got in the way of repower process.
I was thinking that outboard of the port engine may be better becuase of one concept of having shorter runs of hose. I was guessing with shorter runs of hose it would take less flushing to get the goods to the tank resulting in less odor and less water going to the tank, thus utilization of a smaller tank. I have never dealt with this issue before so I am curious to hear what you guys think. I really do not want ot haul 25 or 30 gallons of sh#% around anyways.
I wonder how much liqued volume it takes to flush a substantial load from head to tank. If I kenw that it would be much easier to decide on tank size. I only have a 30 gallon freshwater so that may not be feasible for flushing source either.

Eddy G · Post by **Eddy G** » Jul 31st, '07, 13:40

Kevin: Most holding tanks on 28's are on the outboard side of the port engine. Mine is there and back against the aft engine room bulkhead. On a mechanical type head, I don't think the crap has to make it all the way to the tank every flush. That would definitely fill the tank quickly. Once it clears the bowl, you just stop until the next use. Mine uses raw water and I find that in salt water, my vent gases bearly smell. In fresh water where I keep the boat, it is much worse.

Eddy G.

Skipper Dick · Post by **Skipper Dick** » Jul 31st, '07, 13:56

Kevin,

On a previous boat I had, the potty holding tank was only 6 gallons and it had a macerator pump and a "Y" valve according to Coast Guard Regs. It rarely ever filled up and I never had a problem getting rid of the goods once in legal waters.

Dick

bob lico · Post by **bob lico** » Jul 31st, '07, 14:07

i have a generator on the port side and a 13gallon holding tank on the starboard.i wanted to slow the boat down so i put a 4 stage china bowl with y valve and thru hole. all four batteries are under the passageway in azak batery boxes.in back of the frige i mounted a 6 gallon hot water heater.the boat is perfectly balance with 230 gallons of fuel i FINALLY made the trailling edge of the chines at the stern in the water.
sorry tim it is definitly not a rldt!!!

Skipper Dick · Post by **Skipper Dick** » Jul 31st, '07, 14:07

Kevin,

One other thing. If I did not have a Lectra San on the outboard side of the port engine, I would put it there. It wouldn't be hard to find a rectangular tank that would fit there. But I wouldn't forget the "Y" valve. I got boarded once by Capt. Blackbeard of the Coast Gaurd and he wrote me up. Once they are aboard, they just look all around.

Dick

Mikey · Post by **Mikey** » Jul 31st, '07, 15:31

Since most of us use these boats as day boats why not use the fresh water tank as a holding tank. Don't really need to tote around 25 gallons of fresh water. Carry a few gallon jugs of wa for drinking. Plumb your sinks for salt. wash in salt, rinse in fresh.
Where's the flaw?

IRGuy · Post by **IRGuy** » Jul 31st, '07, 16:21

I bought my tank from Ronco Plastics...

http://www.ronco-plastics.net/pdfs/MarineTanks2006.pdf

They have lots of poly tanks in their catalog, I found one that fit the space I had (on a B33 FBC) and had them add fittings wherever I wanted. As I recall they charged me about $25 for the 8" inspection port, and the threaded plastic half couplings were no charge. If you don't know yet where you want the inspection port you can add one later.. all they use is a plastic flanged deck port and screws.. with marine caulk as a sealant. They were great to work with!

Harv · Post by **Harv** » Jul 31st, '07, 18:08

This is what I have on Windstar. It is a self contained, permanent installation, with overboard discharge. The only thing to remember is to put a lock on the discharge pump when you are not in a legal area to discharge. I beleive, but am not certain, that it can also be plumbed for pumpout stations.

http://www.thetford.com/HOME/Products/P ... fault.aspx

Tony Meola · Post by **Tony Meola** » Jul 31st, '07, 20:25

Like IR guy I put in a Ronco tank. I put it outboard of the starboard engine. It is a little more than 9 gal. and they actually made it to my dimensions. I was thinking about putting in a pressurized head. I was told that will extend the use of the 9 gal tank since you use less water per flush. Another place to put it is back in the shaft alley or outboard of the shaft alley between the stringers. Just don't put it in the cabin. Tony Meola

Harry Babb · Post by **Harry Babb** » Jul 31st, '07, 21:26

My thoughts were to get a Ronco tank from www.tankdepot.com and install it in the below the floor in the main cabin very near the head.

My head is a Raritan Crown. I just figured that the tank should be mounted below the head...........I never considered mounting it above (in elevation) the head. I do not have anything outboard of the starboard engine............but I feel that the engine heat would present another problem to deal with.

Tony.........until you mentioned NOT to mount the tank in the cabin I figured as long as it didn't leak it would be okay. Whats your experience??? Another option would be aft of the fuel tank beneath the steering gear.............

I had also planned to put a fresh water tank in the forward most part of the Vee berth just to use to shower off when after we are finished diving.

Once again I certainly appreciate input from the faithful

Harry Babb

Kingfish · Post by **Kingfish** » Jul 31st, '07, 23:06

On my 28' the holding tank is located on the port side outboard of the fuel tank behind the shaft log on a shelf. We have a "Y" valve to have the option of dumping directly or for pump out.

Because we fish offshore we have never used the pump out method.

It is a electric fresh water flush system.

Not sure of the tank size, but we have never filled it up. When going out a night the guys use it because I don't want to loose anyone in the dark!

During the day the guys piss over the transom.

On cocktail cruises it is used but no problems.

Kevin · Post by **Kevin** » Aug 1st, '07, 08:59

Think I am going to stay in the 6-8 gallon zone. I t is not that hard for me to get way offshore around here. Outboard of the port engine seems to be the most logical place. As soon as I get the airconditioner working I will move on to hooking up the head. It is a brand new macerating toilet, never been used! I will be the first to test it.

Tony Meola · Post by **Tony Meola** » Aug 1st, '07, 19:49

Harry

You can order direct from Ronco. Thats what I did. I was able to have them put the openings for the fittings where I wanted them. Also, I had a pick up tube put in, that exteneds from the top down. That way I did not need the outlet fitting put at the bottom of the tank.

I only say don't put it in the cabin, just in case it starts to emit odors. While it probably will never leak, I am always worried about the gasses escaping from the hose or even the tank. But then its one way of keeping the crowds out of the cabin.

When I was at the NY boat show, and I don't remember if it was Raritan or one of the others, told me that with a pressure toilet, I could extend the time between pump out since it uses much less water per flush. They told to put the pressure pump behind the refrigerator.

Since I am starting my repower, I am thinking about if I should move the tank or not. If anything I am going to try and find a spot so I can pump overboard when offshore. Right now I can only pump out.

Also, the salt water helps add to any odors if it sits in the tank too long.

Good Luck

Tony Meola

Harry Babb · Post by **Harry Babb** » Aug 1st, '07, 22:16

I found this on the net tonight.........

Our application on the 31's is obviously different.......Interesting.....

http://www.maritimesanitation.com/tech-tank.php

Harry Babb

Kevin · Post by **Kevin** » Aug 2nd, '07, 02:33

Even with a couple ladies onboard I sure hope to make a 20 gallon tank last longer than that! Better bring some Peptobismal.

nic · Post by **nic** » Aug 2nd, '07, 18:31

You can get a switch that controls the amount of the "flush" for any of the electric toilet pumps - ie half or full flush, but you can adjust the settings to suit. Just looked ours up, I think it is a raritan option - $120. Good for kids and those unfamiliar with the on-board concept in small boats - which is the only reason you would go to any of this trouble, apart from the law.

Nic

Harry Babb · Post by **Harry Babb** » Aug 2nd, '07, 20:04

Bob/Tony

You both stated having your tanks in the engine room. Raised a couple of concerns...............

Do you have to insulate the tank in some way to protect it from engine heat??

To mount it in the engine room would make the tank higher than the head....will that require a check valve or some sort of loop in the piping to prevent backflow into the bowl??

I just finished rebuilding my Raritan head. The kit that I purchased has a "Flapper Valve" that could be installed on the discharge just before the "Joker Valve" but I would not think that it would be a positive seal.

What do you think??

Harry Babb

Tony Meola · Post by **Tony Meola** » Aug 2nd, '07, 20:55

Harry

You would need a loop. But even with the loop you could get some back flow. I don't remember the brand, I can take a look over the weekend when I head down to the boat, but I put a special check valve in to keep it from backing up. The heat from the engines does not impact it. Its got to be at least 8 inches away from the exhaust manifold on a big block. I have enough room to work on the spark plugs. I limited the size to 9 gallons because thats what fit the best. I did not have to take anything apart to slide it between the engine and the engine box frame. I actually think the ideal place if you can do it is either back in the shaft alley or the stringer outboard of the shaft alley.

The nice thing about Ronco, send them a drawing and they will make it to your specifications. In the shaft alley or between the outboard stringer you could easily go 25 to 30 gallons. That is where I really wanted to be but and may do that as I see how the repower moves along. That would give you enough room to put in a Y valve and a pump so you can dump overboard. Tony Meola

bob lico · Post by **bob lico** » Aug 2nd, '07, 21:52

harry i have a jabsco china bowl using fresh water.toilet has 4 settings on water usage and can flush up to 6' in elevation,on a 31 bert you can locate tank anyware you want.the engine heat has no effect on the todd 13gal. tank.most important note to remember is to use the filter in the vent line and change yearly.like i said before balance is critical and must be planned in advance.keep weight like waste water aft of the bulkhead. the waste piping can and will become pouros it makes no sense to put the holding tank in the cabin.puchase the narrowest tank you can and place tight to the outside of hull max the space to the engine

Harry Babb · Post by **Harry Babb** » Aug 2nd, '07, 21:55

Tony
Actually I do not have any equipement outboard of the Starboard engine.

Before asking the Faithful for help and advice I had not considered mounting the tank above the head..........I have now changed my mind.

I like the idea of not having a possible stinch in the cabin.....I think that installation will be easier than standing on my head in the bildge.

I have found some 12V Jabsco "Waste Pump Out" pumps that will simplify getting rid of the tank contents.

By installing a cleanout in the sewer plumbing at my boathouse I can actually pump my own tank into the sewage system while DeNada is tied up right in her slip.

This weekend I will install the Head and get measurements for the "Holding Tank"

I will be looking forward to getting the information on the loop and check valve that you installed.

Again thanks

Harry Babb

Tony Meola · Post by **Tony Meola** » Aug 5th, '07, 22:34

Harry
I checked over the weekend. I used a standard vented loop I bought at West Marine. The check valve I used is made by guzzler and comes in inch and one half. You can also find that at West Marine. Beckson also makes one. I found the tricky part of the installation was once I was through the bulkhead, plumbing the thing around the engine so it was not in the way of any thing. Think that part out carfully. I used PVC for as much of it as I could. I have the old groco electric head. I am probably going to change it out, but my wast outlet was on the starboard side of the bowl. I came straight back from that point through the bulkhead. Its a little tight but can be done. You may need a second set of hands at some point. Tony Meola

Harry Babb · Post by **Harry Babb** » Aug 5th, '07, 23:17

Thanks a million Tony
I will let you know how it turns out. I am leaving for a business trip Monday PM..........will be next weekend before I get back in town.

Harry Babb

IRGuy · Post by **IRGuy** » Aug 13th, '07, 06:04

Harry...

Did you get the email I sent just before you went away?

Harry Babb · Post by **Harry Babb** » Aug 13th, '07, 16:22

Frank
I did get your email........very informative

I am sure that I will use your experience and information to install the Holding Tank in DeNada.

Pictures were clear and worth a thousand words

I will keep you posted as I make progress

Harry Babb

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