I installed an airhead composting toilet in small
trimaran I owned. It was expensive, but I thought the savings in weight and space was worth it. Instead of using their urine collection bottle, I used a 3-gallon
holding tank which filled by gravity and could be hand pumped out when and where appropriate. This worked very well.
I used the toilet and boat on a 6-day
cruise in SE
Florida and then seven week long
cruise to the
Bahamas. All in all, I was fairly pleased. I experienced less
odor than most boats equipped with holding
tanks. The little electricity needed to
power the small
exhaust fan was hardly noticable, even on an
outboard driven boat producing little
power.
After the 6-day cruise, I simply let it continue to composte without turning until spring arrived. At that time, the contents were dirt and there was no
odor and not even any toilet paper visible. On the longer cruise, I had to empty it twice. Being able to hold for 2-3 weeks with only a few pounds of weight and five gallons of space was a vast improvement over even most large holding
tanks. This time frame allows one many options to find a place to legally dump. If one hasn't let it sit, all the contents will not be composted, but much will, so one is dumping a lot less raw sewage than with a traditional holding tank system. Ideally, it would be nice to let it compost a few days after the last use, but his isn't possible on a long-term cruising boat with only one head. The composting kept up fine with two people using it, but I question if it would be able to keep up with four or more using it on a regular basis.
The only
maintenance issue I had with the unit was the fan. A small amount of
water coming in through the vent can short it out, so I recommend you carry a few spares.
Personally, I think the airhead composting toilet is a great choice for pocket cruisers on short trips or someone keeping a boat near their home on an inland lake, where one can swap out the lower units and let them continue to compost off the boat. However, for larger boats, where the weight and space of a holding tank is less of an issue, I'd stick with a conventional
marine head. Personally, I like the convenience of the gravity feed tanks that can be easily emptied where
legal and appropriate with the simple turn of a valve.