Posted by: Cap'n Fuzzy | February 12, 2016

Digression -Toilets on Boats

In my experience, every boat that has a head, has a disheartening history of malfunctions, from minor smell and discomfort to major disasters. Even before we bought our first live-aboard capable boat, HC37 in Mazatlan, I had vowed to move to composting toilets as dragging around large tanks of semi-liquid sewage has always repelled me.  We had the same issues in our motorhome. Our Mazatlan experience certainly did nothing to dispel these feelings.

HC37 was equipped with an electric pump operated marine toilet, a system which I longed to rip out and heave overboard.  When the pump worked, it was supposed to transfer the offending material to a holding tank, which had been relocated from under the seat in the shower compartment, to a flexible bladder type tank under our foc’sle V-berth.  This allowed the aroma, in the semi-tropical heat, to be enjoyed all night and at the same time, wasted the large storage space the tank displaced.

We were fortunate enough to visit a sistership to our Hunter 37, owned by a couple whose blog we had followed in our search to buy HC37.  They had either an Airhead or Nature’s Head, I cannot remember which and it really does not matter as they are very similar.  The space occupied was only that for the toilet itself; no hoses, no pumps, no tanks under the bed. Most importantly, no smell! A simple spray bottle with a water/vinegar mix to spritz the bowl and voila!  A bag of potting soil to remove every few months.  Yes! Every few months!  I was totally convinced and nothing since has altered that view.  Get a composting toilet, for your boat, for your RV, for your camp, and yes, I am working on one for the house!

Back to HC27, our current boat.  It came equipped with a fiendish device optimistically called a porta-potty but which we quickly renamed the porta-stinky.  It consisted of two parts; the top portion which had a reservoir of clean flush water and the seat/lid and the problematic lower sewage storage tank which was supposed to seal to the top.  It may have, when new.  Ask a plumber, seals are not forever!  Then there was the crack in the lower tank which would become evident as it filled.  This seepage would pool around the base and eventually run down into the bilge, with predictable olfactory consequences.  So we chucked it off the boat and bought a Separett privy kit.  I will add links as I figure out how to do that.

Marine composting toilets may be more correctly described as separating and dessicating toilets rather than composting.  Whatever!  Argumentative devotees apparently can come to fisticuffs in the pub about the differences but in practical terms, as long as it works, who cares?  From our point of view the critical factor was cost.  The two commercial “marine” units will set you back from $900-$1200 USD.  For what is essentially a plastic bucket which you poop in, this defies all logic.  Even Separette, the Swedish company who also makes home composting toilet systems, charges similar amounts if you buy their prettier plastic unit.  It is also too large for the space we have in HC27. But!  They sell their privy kit for $135 CAD and we provided our own plastic poop bucket and urine storage container.

The privy kit was a bit of a sales job to get Sam on board, so to speak.  Apparently, for a portion of the population, it matters what colour of plastic you sit on to, err…do your business.  This has never come up as a topic of conversation, let alone of concern, within my male sphere of acquaintance.   However, attuned as I am to the merest frisson of dissatisfaction surfacing in the Admiralty of the Hearts Content marine establishment, I took note when Sam said, ending on a rising note with a slight quiver, “But it’s bright blue!”

Now, I grew up during the 1950’s and ’60s, the period which bestowed upon the world, porcelain conveniences in a variety of pastel colours.  The Separette privy kit is in a whole different league with it’s much more forthright and honest and to my eye, more nautical hue, call it Chesapeake Bay Blue!  The seat and lid is a shade lighter, an inch or more thick and made of styrofoam, which the manufacturer claims warms more quickly in an outdoor privy than the polystyrene of the separating bowl, when you drop your pants and sit.  A worthy concern, in my winter interactions with outdoor privies.

So, I built the cabinet of Baltic birch plywood and mahogany 1×2, a simple box with a hinged lid.  I made the expedient assumption, when designing, cutting and prefinishing the wood pieces, that the space it was going in to was square.  It appeared to be square, moulded as part of the fibreglass liner of the boat.  I assumed it would be close enough that I could do a bit of trimming and get it to work.  You see how these projects, started confidently around such assumptions, can quickly devolve into nightmares.  I admit there was some profanity and it took much more time than predicted but thankfully for everyone, before the day was out we had a working toilet.  Another potential mutiny averted!  Crew morale soared!

All hands were quickly briefed and the new appliance was tested thoroughly.  The initial doubts about odours in a small space were quickly dispelled and replaced with smiles and comments, like, “hey, it works!” and, “you mean all you do is cover it with the peat moss?”

Still to be added to the system is a positive ventilation fan which comes with the pricier non-privy versions and also with the marine units.  There is a mushroom style cabin roof vent in the head now.  I will replace it with a solar vent and run a 2 inch plastic vent hose down through the cabinet behind the head and into the composter box.  It will then draw air continuously from the box and exhaust it out the roof vent.  The small solar panel on top of the vent cowling produces enough charge on a sunny day to power the small, quiet fan all night.  If necessary I can build a small circuit to provide power from the house battery if the built in vent battery does not charge enough on cloudy days.

Trying to find pictures and looks like I could do another retrospective post on our on-board power systems.



  1. Thank you for posting this. I have been trying to think of a way that I could replace the head in my boat with a composting toilet with out the extreme price. This Separette privy kit looks to be by far the best option for me. A side from the price of the AirHead and others I don’t think I could actually fit one in the boat anyhow. Thank you again for this post.

    • Yes, the height of both the Airhead and Nature’s Head units did not work for us as the cabin sole is raised almost two inches to form the shelf in the liner. By building our own cabinet I was able to keep it to a more reasonable height to clear a cabinet door in the bulkhead behind. It also works better for shorter crew members that way.

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