Will this work?

[jemicha]

I am currently fitting a new holding tank and head into a 1969 Ericson 26 sailboat, and thought I would email you for some advice on what I propose to do BEFORE I cut any more holes in my boat.

What I was planning to do was to create what Don Casey in "This Old Boat" calls a newtonian discharge holding tank and head setup in his book "This Old Boat" .
Attached is a photo/ design of what I was planning to do.

I realize the vent lines are vertical, but i thought I could get away with it being only 8 inches long and given that there are two of them (the green forward one being a scooped intake). As for the aft vent (purple) i was wanting to install a shower drain that would serve double duty as a deck pump out as well. We would rarely be using it as a pump put though, mostly we would be using the newtonian discharge away from shore.

Thanks in advance for any advice,

Michael

 

[Peggie Hall HeadMistress]

The answer to your question is no way!

Don Casey is a very knowledgable guy about a lot of things on boats, but sanitation systems isn't among 'em. Worse yet, I think you've tried to adapt a system he describes into something else entirely that cannot work satisfactorily, if at all. It's SO complext that you just MAY have actually succeeded in designing the first true onboard Chernobyl! :dance:

So let's simplify it...here's what I'd do on a 26' sailboat:

A 5-6 gallon "MSD" portapotty. "MSD"=designed to be permanently installed and fitted for pumpout and also dumpout at sea, with the addition of a macerator pump or manual diaphragm pump. Neat, tidy, self-contained...you COULD carry it off the boat if you had to. Holds 50-60 flushes, which is at least 3x the flushes that a 10 gallon tank connected to a manual marine toilet can hold. No holes in the boat, just a pumpout line and a vent line (and a y-valve and macerator if you want them). Total cost about $200 for the potty, hoses and deck pumpout fitting...add $150 for a y-valve and "dump" pump.

Neat, tidy, self-contained, no moving parts to maintain...no thru-hulls...no vented loops needed (you don't show one in the toilet intake, but you'd need one thee)...a no-brainer for guests to use...clog proof... Thetford even makes an "electric" version that uses AA batteries. What more could you want in a sanitation system that doesn't use up more than half your storage space?

Check out the Thetford 365 MSD ("manual" version) and the 465 MSD (electric version). http://www.thetford.com/HOME/PRODUCTS/PortableToilets/tabid/83/Default.aspx One of them is everything you want it to be!

 

[jemicha]

Thanks for your quick response Peggie, and I certainly would not want a Chernobyl on my hands!

We have had a portapotty on the boat and were wanting to move on from that. We were getting tired of walking aft with a stinking and sloshing bucket of waste and then having to balance under the lifelines to pour it into the sea with it splashing back at us.

Any ideas how to make a holding tank work?

I understand the intake will need a vented loop, I was thinking that as I drew it out and saw how close the waterline is to the rim of the bowl.

What could I do to simplify the design?

 

[Peggie Hall HeadMistress]

I don't think you get it yet...

I swear, people see the word "portapotty" and then just stop reading and dig in their heels!

If you'll just read what I wrote AFTER the word "portapotty , you'll see that you DON'T carry an "MSD" portapotty off the boat or dump it over the side...it gets pumped out or dumped same as any other holding tank. The only difference is, the bowl and tank are integrated...a self-contained system that puts the tank directly below the bowl, eliminating the need for any plumbing except a tank discharge and vent line and also the need for ANY toilet maintenance.

Any ideas how to make a holding tank work?

Sure. Install it under a settee or the v-berth (which, on a 26' boat may amount to the same place). You'll need some 1.5" sanitation hose to connect the toilet to it. The tank and that hose should only occupy about 25% of your storage space...you shoudn't lose more than another 10-15% to the pumpout line from the tank and to any plumbing and pump to dump the tank. Then there's the toilet...which needs a thru-hull to bring in flush water, a vented loop between the pump and the bowl to protect the boat from sinking in its slip if you leave the toilet in the wet mode when you leave the boat or the wet/dry cam assembly fails and leaks while no one is aboard to notice that bowl is overflowing. It'll also require regular lubrication to keep it working at all...and the odor from sea water left to sit and stagnate in the intake line and pump will knock you off your feet each time you come back aboard. Best news, manual marine toilets put an average of about 2 liters/flush into the tank...which means a 10 gallon tank will only hold about 20 flushes--barely enough to last two people 24 hours aboard.

Now...go back to my first reply and actually READ past the words "MSD portapotty" this time and decide which way you really want to go. Meanwhile, maybe at least a few of the people who've opted for a 5-6 gal MSD potty will chime in and tell you how much THEY like it.

 

[jemicha]

Thanks for your response Peggie. You're right, I was thinking of the RV type portapotty as that was the type that was onboard before. I will talk to my wife and see what she thinks.

Thanks for also giving some tips on how to make a holding tank work.