The galley was nearly clean with only a sink full of wash water draining, when I heard a sickening dull thud. A distinctive thud that I recognized as the sound of a duck bill valve everting in response to a water outlet obstruction. How did I recognize this sound, you might ask? Experience. On one or more occasions in the past, I had activated the sump pump that drains our galley sinks without having first opened the thru-hull valve. But, this time the thru-hull was open. What was obstructing the system after a winter layover?
Our Dutch-built sailboat has deep double stainless steel galley sinks. We love them for many reasons. We also hate them. Or did. The bottoms of the sinks are barely above the water line. Situated off-center to port, the sinks didn’t drain very well normally; when cruising offshore, they were virtually unusable, especially on starboard tack.
About fifteen years ago, I installed a galley sink sump and sump pump to facilitate drainage. The following photo shows the installation. The sump is actually a modified plastic wastepaper basket. I suppose I should have used a proper sump, but one needs to improvise when in the Caribbean, and this wastepaper basket has served its purpose flawlessly since installation. As labeled but unseen in the photo, the sinks are plumbed into the top right side of the sump. Water drains from the bottom of the sump into a hose that runs below the thru-hull valve and then up to an inlet to the sump pump. The outflow from the pump leads to an anti-siphon loop that runs up and back through a chase that houses a deck drain immediately behind the galley sinks. The return from the anti-siphon loop leads to the thru-hull valve to discharge overboard.
The sump pump is a diaphragm pump, a Whale Gulper Grouper, and is attached to an inline tail piece that includes two duck bill valves, one at the inlet and one at the outlet. These valves are basically the same as used in many marine toilets, and serve to keep the discharge water heading in its intended direction to the thru-hull rather than back into the sump.
Martha and I were gone all of January and missed the many storms and choppy harbor seas that hammered the marina. On return, neighboring boaters told us of all the debris that had washed into the harbor from the runoff that followed those storms. We witnessed a lot of debris ourselves, and considering our problem, the only thing I could envision was that the galley outflow must have been occluded by the same harbor debris. How to find and clear it?
Now, where is this sump apparatus located? In a “convenient” cabinet, just aft of the sinks and low to the cabin sole. And, of course, it’s obscured by the many galley and general maintenance items stored there. Gaining access was thus the first project in getting to the project.
Remedying the situation requires uninstalling the sump pump, freeing the tail piece from the afferent and efferent hoses, extracting the duck bill valves from the tail piece, and then reverting the duck bill valves or simply replacing them with new. I chose the latter. West Marine had them in stock—saved me rummaging through the spares compartment for those I know I have on hand.
I also decided to replace the pump’s diaphragm since I was “in the neighborhood,” and I had to replace the blue collar that mates the sump pump to the tailpiece because it was cracked.
Fortunately, WHALE still makes this pump and replacement parts are readily available. Sourcing them wasn’t difficult, but it was another project to get to the project. Of course, all this had NOTHING to do with the swamp I had come to drain, viz., finding and eliminating the source of blockage in the system.
The hose leading to the thru-hull looked a darker brown than its usual nasty self, so I concluded that a blockage in the hose was the source of the obstruction. After removing the hose from the thru-hull (it’s a two-inch hose), it was easy to see that it was packed tight with small wood chips, pretty much right up to the waterline. Fashioning a hook from a coat hanger, I clawed out two cups of debris.
Yuk! Ample explanation for the obstruction and subsequent failure of the duck bill valves. I flushed the hose with several liters of water, testing the new pump installation in the process, and then reassembled the entire system, confident that it was working once again.
I know there was a lot of debris in my slip and there was a lot of chop during the January storms. My assumption is that the constant pounding of the waves against the hull drove this debris into this relatively large discharge hose, packing it so tight that it occluded water flow. An aft sink discharge was similarly plugged, but easily cleared with a plunger. Ironically, my intake lines didn’t suffer the same fate, and my raw water filters are clean.
Nevertheless, check your raw water filters if you haven’t already, and I hope your discharge lines aren’t filled like mine were.