Hot news - Composting Toilets

Aug 2012 Pip Wick

Our first cruising boat was a used, strip-planked yawl purchased in 1968. She raised three children and two adults for twenty-five years. Late in that time we started to develop ideas for our ideal sailboat and when our life money scheme came to fruition, we started the project.

We built Lucayo to Roger Marshall’s design at the Brooklin (ME) Boatyard during the fall, winter, and spring of 1992/93.

She’s wood-epoxy construction; three layers of 1/8” plies, cold molded over ¾” strip planking. Lucayo is 48 feet overall, 13.4 feet wide, weighs 17 tons at full load, with six foot draft. She has a low-aspect, bulbed, fin keel that allows us to cruise the Bahamas, but it is deep enough to make her efficient to windward without a centerboard. The yacht is medium displacement and a sea-worthy offshore cruiser. We meant her to be comfortable under power as well as sail, a full powered sailboat. She has taken us from Venezuela to Newfoundland.

I was allowed to work on the boat with the building crew, so I developed a close relationship with her and the boatyard from the beginning. It was the opportunity of a lifetime, and the most enjoyable winter I ever had. Also, I was available for consultation at a moment’s notice, which might even have helped speed up construction.

Now, after 12 years of operation, we have added some features to Lucayo that have changed the boat considerably, and I want to share these with fellow sailors over the next few months.

We took the boat from Maine to Southwestern Newfoundland as a shakedown cruise, about 1000 miles. Our fellow cruisers in Newfoundland brought up almost as much discussion of our composting toilet system as our electric propulsion (see next month's write-up).

Lucayo sports two “Air Heads”. These are basically composting toilets with the different wastes separated into two holding tanks. With proper stewardship they are odorless, quiet and lack most of the mechanical and storage problems of modern waste systems. The user needs to maintain a sufficient amount of peat moss in the solids tank, and renew the half cup of sugar in the liquid tank at each emptying.

If there is too little peat moss, or too much liquid, the tank is filled with raw, smelly sewage. The right amount of peat yields a bucket of compost. The toilets need to be monitored, and the solids not too wet. We don’t need great amounts of peat moss, a cubic foot would go for many years.

The liquid tank needs to be emptied every two or three days with two of us using it. We aim to empty the liquid tank when it is just over half full, but have missed more than once, usually because we misread the sight gauge on the liquids tank. Healthy urine is almost clear and hard to see. The gauge needs to be kept clean by a Q-Tip every so often.

We like to be at least three miles offshore to empty the tanks, or the wastes can be brought ashore and flushed down a regular toilet. We usually take the solids ashore after a season and bury them as compost. On longer trips we are often more than twelve miles out and can dump without hurting our consciences, or the environment, the solids tank needs emptying every two weeks or so with two continuous users.

These toilets are brick simple mechanically, especially compared to the pump systems I grew up with. They have no pump out tanks and no through hull fittings. Even with a little mismanagement of the peat and sugar they rarely smell at all, so even a slight odor is worth investigation. Except for getting the additives wrong, the only problems we had was when peat moss got into the drain system to the liquid tank and plugged it. Wastewater accumulated in the solids tank and we had to dump it and clean it out. There is only one working part, a hatch over the solids tank, held shut with a spring.

Would I do this again? Yes, but maintenance is more art than science. It takes time to get used to the set up. It isn’t an ideal system, I doubt the acme of heads has been developed, but I’ve lived with worse.