You are aboard someone's boat, and after an afternoon of sun and adult beverages, the inevitable pressure buildup happens. But you've heard stories about marine toilets, and are filled with disquieting thoughts... What if I do something wrong? Could I sink the boat? What if I have to call the boat owner? What if I have to call the boat owner with my work product still in the bowl?? So you cross your legs and contemplate swimming, even tho the water temperature is only 54 degrees. And you vow to never drink beer on a boat again.
Never fear. As your guide to all things living aboard, I will take you thru those fears, and give you the confidence of foreknowledge.
The marine toilet (head) is different from your familiar household appliance, because it is adapted to a different environment:
- First of all, because of the cramped quarters onboard, it is smaller. There will be overhang. It's not you.
- Your household toilet uses about 5 gallons of water per flush. Now, at 45 gallons, Eolian has a very generous holding tank, but with a household toilet, that volume could only accommodate 9 flushes. So the marine head does not flush like a household toilet, in order to reduce the volume of waste. And because fresh water is precious (all you have is what is in your tanks), the marine head flushes with seawater.
- Your household sewer plumbing is 3" or 4" in diameter. On a boat, the plumbing is 1.5" in diameter (it's the white hose in the picture), and at least as critically, the path from the bowl to the holding tank is very tortuous indeed. You may have heard the adage, "Don't put anything in there unless you have eaten it first," (small amounts of tissue exempted). Believe it. If something jams in there, I am the one who has to disassemble the system and dig it out, and everything that piled up behind it.
- The marine head does not use gravity to do its job. Instead, a pump is used to move the waste from the bowl to the tank. There are manual pumps, electric pumps, vacuum pumps... but there is always pumping involved.
So. How does this device, which looks vaguely like it might have come from Frankenstein's laboratory, work?
The familiar household toilet has one, "do everything" lever: flush, and the contents are swept away and the bowl is rinsed. With the marine head, these are typically two separate activities. On Eolian our heads are Groco Model HFs, and they work like this:
- Operate the pump by alternately pulling up and pushing down the handle. This will alternately draw contents from the bowl and then push them into the white discharge hose. Continue until the bowl is empty, or nearly so.
- See that small brass lever? It is in the horizontal position in this picture. In this position, it prevents the entry of the flush sea water. Move the lever to the upright position, opening the flush water valve.
- Again operate the pump handle. Now with each complete up/down cycle, flush water will rinse the bowl, and then be pumped into the discharge hose. Rinse enough to be clean, but don't overdo it - remember that 45 gallon tank. If it is night, enjoy the swirling points of light as excited plankton spin around the bowl.
- Return the brass lever to the horizontal position. THIS IS IMPORTANT! If the flush valve is left open, seawater will slowly fill the bowl, overflow onto the floor, and... (so, yes. I suppose you could sink the boat...) Always leave the head with the brass lever horizontal.
- Pump out any remaining rinse water. The bowl should be left empty - this is a sailboat. We don't want remaining water to slosh out when the boat heels underway. Even if we are tied at the dock, it is a good habit to get into - leave the bowl empty.
Fear gone? I hope so. And armed with this knowledge, if the next head you encounter is not a Groco, at least you will have the basics down, and should feel confident.
Now go ahead, uncross those legs...