Composting heads?

[dgadee]

Seen references to these. Anyone here use them? We are onboard for 4+ months a year and I wonder about adding one to the project boat.

 

[bergie]

It works fine, just carry enough coconut coir bricks. Also, everybody must sit to pee.
And you can maybe get rid of some thru-hulls.

We switched to one back in 2021 as there are no pumpout options available in Berlin during winter. Since then, no clogged heads, no pressurised poop incidents, joker valve replacements etc.

None of the off-the-shelf composting toilets fit our boat, so we bought one of the Kildwick kits and built our own.

 

[geem]

Seen references to these. Anyone here use them? We are onboard for 4+ months a year and I wonder about adding one to the project boat.

I have been on boats with them. They stink. I had to laugh when the boat owner was telling me how great it's is "and it doesn't smell" believe me, it was smelly.
We switched from troublesome Jabsco toilets to Lavac. They suit our cruising needs as liveboards far better than Jabsco. We find the Jabsco is not up to the constant use of a liveaboard lifestyle. The Lavac is more robust with far less wearable parts

 

[dgadee]

I was thinking they may save having to put in a black tank.

 

[Refueler]

When I lived in UK ..... the Wife and I decided to try one for 'disposing' of Dog Poop .... (it was advertised / sold as designed for Dog Poop).

What a mess ! It stank ... it didn't do as advertised ...

Would I consider for a boat .... I will let you guess the answer to that ..

 

[bergie]

I have been on boats with them. They stink. I had to laugh when the boat owner was telling me how great it's is "and it doesn't smell" believe me, it was smelly.

That is always a user error. Most typically, allowing liquids into the solids side. See the "sit to pee" point in my post above.

The head needs ventilation for the drying process to work, but otherwise it is pretty simple and reliable. We've used it between winter the dry air of Northern European winter and the humid tropics. Primary difference is how much composting medium you need to use.

If you've never used one before, there's a bit of a learning curve. For us the advantage was that many Finnish summer cottages, and all national parks (and most of the popular anchorages, too!) have composting toilets, so we're used to them.

 

[Caer Urfa]

I surveyed a boat with one and the stink was awful I thought someone had died, stick to a good old sea toilet

 

[Cerebus]

Is it a case of improper use or are they just bad?

Never seen one or experienced one.

I will try YouTube for a look.

 

[Rum Run]

I have been on several (3) liveaboard boats with "composting " toilets and they were all fine. The key issue is not getting the dry side wet,particularly with urine.
I put the quote mark in because they are not actually composting but desiccating: the sawdust or whatever just dehydrates the bacteria in the faeces which then die and cannot smell much. Real composting is a different process as all proper gardeners know.

 

[oilybilge]

Why do you have to sit to pee?

 

[KevinV]

Why do you have to sit to pee?

The pee goes into a tank at the front, faeces into the sawdust to be dried out. Urine in the dry bit makes it all go horribly wrong

 

[thinwater]

For decades I thought composting toilets were the dumbest thing ever. I'd stayed in some cabins with terrible, unendurable units. No way I would have one on a boat.

Then I was asked to research the topic and write about it for a magazine. I did, and as an engineer, I built a simple one for testing and put it in a large unused bathroom (my wife has bad knees and does not do the stairs much). And without special ventilation and by following the rules, I had that inside our house for 4 months, before ending the expereiment and building one from the lessons learned for the Corsair F-24 trimaran I day sail. There was no smell, once I worked out the details. I had been converted from "Ick, no way ever" to "Best solution for a day sailor or weekend boat." A complete 180 of my opinion.

1. The urine and poo MUST be separated. If this is not done rigorously through the use of a diverter seat it will stink. This is also why clumping cat little really helps; the poo and pee come out of the cat in different places, and if it clumps on contact, they don't mix. This is the most important key.
2. An effective absorbent must be used. It must cover the waste. It must wick moisture from the surface rapidly so the the surface crusts. It must be dry. Coconut Coir works, but the manufacturers of several heads told me that shredded aspen works better (comes in compacted bags in pet stores), and having tested many things, it matters. Mill shavings mixed with sawdust can work very, very well, but straight saw dust does not. Peat moss does not work well and coconut is somewhere in the middle.
3. You must add a chemical to the urine tank to prevent fermentation. Vinegar is good, citric acid is better, and some of the urine neutralizers used by janitors are even better. Untreated urine can smell worse than the poo. It also helps to keep a spray bottle of citric acid solution in the head to spray the diverter after use. This also keeps it clean and prevents scale. It takes very little. Keep it out of the main compartment.
4. If someone gets the compost wet by diarrhea or peeing it it you need to dump it and start over immediately. It will not recover.
5. You can get flies if it is wet. Adding DE with the absorbent helps. I have not had this problem.
6. A small sachet (15-30 grams?) of pool chlorine hanging just inside but out of the line of fire helps. This was suggested to me by C-Head. The moisture triggers the release of a tiny amount of chlorine, sufficient to oxidize any odor, but not enough to leave the head. If the head is used a lot the release is more, if less the release is less. It also keeps the flies away. It typically lasts 3-6 months, but longer in the winter. I get a year, but we use the head very little; it's a day sailor. There should be a secondary, snug fitting lid between the seat and the container.

I would not generally chose to go this way for a cruising boat. Conventional head systems have advantages. But there are several strong cases:

• No pump-out available, like a lake. MUCH better, in every way, than a porta-head.
• Winter in subfreezing climates. Nothing to winterize.
• Daysailing. Chose a non-mix type, line it with a bag, and pull the bag each time it is used. Much easier than hauling it home (many of the marinas around here strongly disallow disposal in the rest rooms because of messes) and much better than leaving it to molder on the boat.
• Lighter. A full porta-head is awkward and a good way to hurt your back. Even clean it is heavy with flush mixture. My composting head weighs only a few pounds empty, and to service it I just pull the bag and leave it in the skip. Not strenuous.

Blog post on my expereince. I'm on my 5th year.

I've also been around a good many conventional systems that stunk because they were either poorly operated, poorly designed, or poorly maintained. A few negative antidotes only points out that design details and operation details matter, as they always do.

 

[dgadee]

Very useful. Thanks.

 

[ShaneO]

I had one for several years living on a canal narrowboat, and liked it enough that I’ve converted one of the heads rooms (although I fail to understand why two heads is considered appropriate on a space as limited as a sailing boat) to a composting toilet (still have a sea toilet in the other). A catastrophic failure of a composting toilet isn’t that bad, certainly won’t leave the life-long psychological scarring of a holding tank system’s catastrophic failure.