adding waste tank

[satch415]

New member with new-to-me 29' sailboat that doesn't have a holding tank installed but does have a head. My current setup is a manual Jabsco that discharges overboard and looks to be correctly installed with vented loops for raw water inlet and discharge to seacock, based on pictures from the Jabsco site. I was hoping to attach pictures but I couldn't figure that out.

My proposed setup from the West Marine site is there "Favorite" with
everything going into waste tank first and then discharged from there.
I can buy a 18 gallon pre-manufactured tank with 2 discharge outlets and 1 inlet with air vent and anti-implosion vent ALL on TOP of tank as I've seen suggested. This will fit on the portside V-berth next to the head on the other side of bulkhead. The head can discharge to the tank only about 2' away. I don't need to vent this line from head to tank, Do I? It will rise slightly to top of tank, maybe 6".

I thought the easiest thing to do was to take the discharge line currently going to the seacock and put it on 1 of the tank's discharge outlets AND then cut in a Whale Gusher manual diaphragm pump between the tank outlet and the vented loop. Should be finished with that line.

I would then put another hose on the other discharge outlet and run it up to the deck pumpout, NO VENT required, right?
The biggest challenge will be cutting in the whale pump and fitting it all in the locker behind the head.

I hope my explanation gives accurate info.

Does this sound right? Any suggestions to improve setup?

[tkeithlu]

Welcome to the forum, Satch415.

While I didn't catch any problems with your plan, I will, as always, defer to Peggy Hall on all matters poop related.

[peghall]

I see you've just joined our merry band of boat owners...welcome aboard!

I suggest that instead of buying an "off the shelf" rectangular tank with pre-installed fittings in so-called "standard" locations, you check out the tanks available from Ronco Plastics Ronco Plastics Home Page They make TOP quality thick-walled water and waste tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular, and they install fittings in the sizes and locations specified by the customer when they make the tank. There are retailers who sell Ronco tanks, but Ronco sells direct for a much lower price...and they're great to work with.

When looking at drawings it's important to know that there is no top or bottom until the fittings go in, and YOU decide where they go. So rotate, flip in any orientation to find the tank that fits your space.

And I'll be glad to answer questions, help you select fittings locations and even the best location for the tank itself....which, btw, should be within 6' of your toilet because that's as far as most manual toilets can move bowl contents with a reasonable number of pump strokes without a lot of help from gravity. We'll also want to talk about hoses...sanitation hoses are NOT the best place to "go cheap" if you only want to do this job once!

And btw...I have no connection to Ronco or any other equipment manufacturer. My recommendations are based entirely on what 30 year of experience has taught me are the best choices.

--Peggie

[satch415]

Thanks for responding peggie.
I looked a little at Ronco, PlasticMart, and Tank-Mart. Tank-Mart will locate the holes where you want like Ronco, even on top, while PlasticMart will only do sides. The v-berth has limited space as the water tank is in the forward V-berth, centered. I could go across the front of the v-berth but then I'm losing more storage space on both sides of v-berth, so I thought using only one-side might be better. The port side allows me a max. length of only 29" with a width and height around 14-16". If outlets are on top, the tank can't be as tall. The off-the-shelf one was 28.25" length, about 14" tall which would just fit height wise. It's a mis-shapened space and tough to work with. I'm at the planning stage, so nothing is set yet. This wil lbe a Fall project when I'm out of water.

I appreciate you offer to help me and yes, I only want to do this once and correctly.

[Don C L]

What 29' boat do you have? My 29' came with a holding tank that was actually mounted ABOVE and behind the head between bulkheads. It was custom made to fit the space and held 6 or 7 gallons I think. I didn't really like it for a number of reasons so I took it out and went with a 5 gallon porta-potty and capped the thru-hulls. I like the lack of plumbing and there are varieties of self-contained heads that can be pumped out. But that is one option, to mount the holding tank in the cabinetry behind the head, if there is room.

[GordMay]

Greetings and welcome aboard the CF, satch.

[peghall]

Plastic Mart and Tank Mart are retailers that carry Ronco tanks...Ronco sells direct for about half what their prices are. Most off-the shelf tanks have walls that are only .25 in. thick, making it necessary to support all 4 sides .Ronco's tanks have walls that are 50% thicker, able to support the 8.333 lb/gal weight of the contents without bulging or flexing. You should be able to find the size/shape you need among the 400 plus tanks in their catalog. And spec the fittings wherever you want 'em to be without an upcharge for the first 3...minimal charge for one more.

I was about to suggest that you install 2 discharge ports till I realized you'd beaten me to it...one for a dedicated line to the deck pumpout fitting, the other one directly to the thru-hull using whatever type of pump you want to use and a vented loop...thus eliminating the need for a y-valve in the the pumpout line. No vent required in either line.

However, the tank MUST be vented to the outside of the boat...and based on your planned location for the tank I'd put the vent fitting at the bow end of the tank--on the top if you can manage at least 3" in. clearance above it--and run the vent line forward to exit the hull about a foot below the toe rail. Add I strongly recommend a 1" vent line to a bulkhead fitting if you want to prevent odor out the vent when you flush. We can discuss this in detail when you're ready order the tank.

--Peggie

[Nicholson58]

Ronco. They also offer wired shapes that might increase your capacity. You may have to contact them directly. I used a Groco 1/2 inch bronze through hull to the transom for a vent. You really don’t want the thing to ever vent in the boat. Make sure the tank is waste rated. This is 3/8 inch thick and high vapor impermeability. As Peggy noted, ports where you want them.

If you will operate primarily in the US and other picky places the manual pump out you suggest with lockable through hull will pass. In the Caribbean tanks are preferably above water line and gravity dump with a Y valve ahead of the holding tank, also lockable.

[peghall]

Don has an idea worth considering...

On any boat much smaller than about 30' a self-contained system—an "MSD" portapotty--makes a lot of sense. The "MSD" designation in the model name/number means it has fittings for a pumpout line and vent line, and is designed to be permanently installed (actually just sturdier brackets than portables, so you could still take it off the boat if you absolutely have to), which means that although it's still called a PORTApotty, you don't have to carry anything off the boat to empty it. You can even put a y-valve and the pump of your choice in the pumpout line to empty the tank at sea.

A 5-6 gallon model is household height and holds 50-60 flushes...you'd need at least a 30 gal tank to hold that many from a manual marine toilet and I'm not sure a "composter" can hold that much poop and organic material needed to absorb the liquid in solid waster (which, btw is about 75% water). No plumbing needed except a vent line and pumpout hose--so no new holes in the boat...and -0- maintenance needed except for rinsing out the tank--which you can do with a bucket while it's being pumped out. Total cost including the pumpout hose and vent line is about $250--a fraction of what you'd spend for toilet, tank and all the related plumbing needed. And the best part is, you have all the advantages of a toilet and holding tank without giving up a single square foot of storage space.

If this idea appeals to you, check out the Dometic 975 MSD Sanipottie ...Defender has it
Dometic SaniPottie 975MSD Toilet @Defender

--Peggie

[Don C L]

Originally Posted by peghall

If this idea appeals to you, check out the Dometic 975 MSD Sanipottie ...Defender has it
Dometic SaniPottie 975MSD Toilet @Defender

--Peggie

Hi Peggie, Defender used to have a model with a large lower tank, ceramic bowl and full size seat and fresh water intake. Do you know if that model got discontinued? I can't find it now.

edit, oops, found it:
https://www.defender.com/product.jsp?id=105225

[peghall]

The Dometic (formerly SeaLand 711-M28 Marine Traveler...I've always loved that toilet! It uses pressurized fresh water, has a china direct drop RV toilet atop a 9 gallon tank, requiring only enough water to rinse the bowl and you can even add water to the bowl ahead solids. I rarely recommend it because it has just ONE drawback: the tank has a 19.25" x 17.5" footprint, making it too big to fit in most sailboat heads.

If you have room for it in your head and your budget, go for it...you'll love it!

--Peggie

[roverhi]

Space on a 29' boat is critical for locating a holding tank. Be sure you have the room to mount a tank and can live with lost space.

The PO wiped out the hanging locker to retro-fit the holding tank which ruined the livability of the boat. Replaced the head and holding tank with a C-head desiccating/composting head and all is now right with the world and the boat no longer smells like an outhouse.

[satch415]

The MSD is interesting although the idea of a "porta potty" was not what I was originally thinking about but it does have advantages. Since the toilet was already installed a holding tank was my initial idea. I can probably squeeze a 25 gallon tank in the available space without modifying the space but it would be tight. I can probably do the whole job for $600.
One thought was to initially do the MSD for less than $300, and after awhile, if I didn't like it, I could do the holding tank.
Thank you for all the replies, appreciated.

[Don C L]

200 lbs. of poop is a lot of ballast on a 29 foot boat, if you fill 25 gallons!