The Ancestral Latrine
On early sailing ships, the crew used the vessel's sharp prow, which was known as the beak head, as an open-air latrine. The latrine was named for its location - an appellation that still survives, even though the head came in from the cold more than a century ago.

Marine toilets or 'marine heads' as they are called, come in both manual and electric versions. To keep the gaskets and the valves of the pumps functioning smoothly during your bareboat charter, simply pour in about a quarter of a cup of vegetable (cooking) oil into the bowl of the marine toilet once daily and flush it through the system.

The chief problem you could encounter (with a marine toilet) is their cantankerous inclination to clog, especially if used as receptacles for such objects as cigarette ends, tampons or soap wrappers etc. To avoid an unpleasant job or an expensive service call, one or more important things for bareboat crew to remember on a bareboat charter yacht is that, with the exception of toilet paper nothing goes into a marine toilet that has not passed through your mouth first... a service call to clear a blocked toilet will be charged to you...The most vulnerable spot is usually the internal discharge valve that prevents waste from being drawn back into the pump. This valve is known as the joker - possibly a corruption of the word choker, because anything that is lodged there effectively chokes the pump. However the problem can be fixed with relative ease...just open the joker and remove the obstruction...see the diagram below.

To remove foreign objects carelessly or inadvertently dropped into the bowl of a marine toilet, unscrew the discharge tailpiece from the discharge line and lift out the rubber joker valve. If the valve is in sound condition, wipe it clean and reassemble the unit; otherwise, replace it.

In a typical hand-operated marine toilet, the up-and-down action of a pump circulates raw water and flushes waste into the holding tank of a bareboat - or overboard - when the flush-valve lever is opened.

If a manual pump handle is hard to operate - or an electric pump seems balky - be sure the seacock is wide open and there are no kinks in the intake and discharge lines. Movement of your bareboat underway can shut the seacock or crimp the intake line, thereby cutting off flow.

How the marine head works

The up-and-down action of a pump circulates raw water and flushes the waste overboard or into a holding tank on your bareboat if a manual pump handle is hard to operate - or an electric pump seems balky - be sure the seacock is wide open and there are no kinks in the intake and discharge line.

To use a marine head:

1. Push the black lever to the 'wet bowl' position and then pump until water enters the bowl.
   
2. Use the marine toilet... after use, with the lever still pushed to the 'wet bowl' position...pump for 15-20 strokes to evacuate the bowl and flush out the discharge lines.
   
3. Now push the lever to the 'dry bowl' position...and pump the bowl dry.
   

The seacocks for both the 'sea water' inlet and 'waste outlet' pipes in the sewerage bilge are set in the open position at the commencement of bareboat charters...they should not need adjusting in normal circumstances.

A cutaway view of a manual toilet pump on your marine toilet traces movement of water during the intake phase of operation and pinpoints maintenance spots.

On the downstroke, as shown here, the piston draws clean water through the intake valve, while forcing waste water from the cylinder into the discharge line through the joker valve.

On the upstroke the clean water will be forced past the outlet valve and into the bowl. The upstroke also draws a new charge of water and waste from the toilet bowl into the cylinder.