A Holding Tank for Dummies: In Search of the Perfectly Simple, Idiot-Proof Holding Tank by Chris Doyle
AFTERMARKET LOWER UNITS FOR: • MERCURY • YAMAHA • EVINRUDE • MERCRUISER ALPHA ONE • GENERATION 2 • BRAVO BUY FOR LESS THAN HALF THE PRICE OF OEM.
ST. MAARTEN CALL 011 599 587 7469 for a price or email: caribpower2004@hotmail.com
McIntyre Bros. Ltd. TRUE BLUE, ST. GEORGE’S, GRENADA W.I.
Parts - Repairs - Service Outboard Engines 2HP-250HP Duty-Free Engines for Yachts
TOURS & CRUISES - CAR & JEEP RENTAL
PAGE 31
PHONE: (473) 444 3944/1555 FAX: (473) 444 2899 email: macford@caribsurf.com
CARIBBEAN COMPASS
YAMAHA
JULY 2011
Many years ago I wrote an article for Compass titled “Hold the Holding Tank.” My point at that time was that there was no evidence that the small amount of waste from yacht toilets did any ecological harm, so why not just flush away? My opinion regarding ecological damage has not changed; as far as I can see there is none. The marine environment that most of us anchor in can easily deal with the small amount of effluent from yacht toilets. But these days, when there are so many more yachts, I look at it more from an aesthetic point of view. It would be much better not to flush the heads if there is anyone swimming anywhere close, and there are times when it is good to be able to control just when your effluent goes in the sea. For example in Fort de France, Martinique; Bridgetown, Barbados; and Gosier, Guadeloupe, many locals like to swim around the bay, among all the yachts, in early morning. They should certainly be able to do this without even having the slightest chance of meeting anyone’s discharge. In addition, more and more marine parks are asking us to have holding tanks, and I think it is time to comply. I think of it as a way to be courteous to others. Ever since my catamaran, Ti Kanot, was built, I always intended to have a holding tank, but it has taken some ten years to get round to installing one; plenty of time to think about how it should be done and to come up with the simplest, easiest, most dummy-proof way of achieving it. In searching for a design I was influenced by an incident that happened many years ago. I was cruising in Sweden on a yacht with a holding tank. It was a complicated affair with lots of hoses and valves, including a Y-valve. I did not understand how it all worked and somehow I managed to flip the wrong switch and create a brown disturbance around the boat that did not move for hours in the calm water — very embarrassing. I wanted something simpler and more foolproof than this. I see no objection to fecal matter ending up in the sea. The solution to pollution is dilution, and this is best achieved by depositing small amounts over a wide area in deep water. It is perfectly ecologically friendly; the sea, after all, deals with the feces from many more animals than humans — whales, dolphins, sea lions, fish and seabirds, to mention just a few. It all gets recycled. I remember once, while anchored in very still water in Trinidad, being curious about what happened after I pumped the head, so I went to the stern and looked. The effluent was quickly set upon by a school of sergeant majors, which seemed to find it the perfect breakfast snack. It is just a question of whether you dump effluent in an anchorage, or farther out at sea where there can be no logical objection. The idea of using pump-out stations does not make any sense, except for long-term marina guests. Anyone who wants to know where land-based sewage ends up can take a whiff of the water as they sail past Point Saline in Grenada or Pointe Plum in St. Martin. Eliminating the pumpout mechanism makes Hold it! This simple installation offers the option of discharging waste appropriately the construction of a holding tank much easier. You can also forget the Y-valve and any extra hoses. It struck me that the simplest possible holding tank was a small tank plumbed right in line with the effluent hose. The effluent from the toilet goes into the top of the tank, flows through the tank and out of the bottom of the tank, from where it goes straight into the sea. At this point you have a normally operating toilet with a tank plumbed into it. And for much of the time you might well want to use it like this. To make this work as a holding tank all it needs is a valve on top of the tank with an air vent. To deploy the tank, just close the seacock and open the vent. Waste will now start building up in the tank instead of flowing through. To empty it, simply open the seacock. Gravity feeds it right out, then you close the air vent. To flush out the tank, simply pump the head with the air valve closed and the seacock open. The tank does not have to be that big, just enough to hold a few flushes. I had lots of different ideas as to how to do this on my boat, but since it was new territory I opted for something I could see and remove easily if the project turned out badly. I had my friend Rolly in Trinidad build me a box that would fit in the space behind the toilet. It is 26 inches wide, 8 inches high and 6 inches deep. He built it out of ply and fibreglassed it inside and out. Before we glassed the lid on I installed a four-inch inspection hatch at each end of the top, so if there were ever any blocks (so far there have not been) I would be able to deal with them. I plumbed the vent into a nearby rope locker. We gave the tank about a five-degree list to starboard to ensure it would completely drain. We attached the hoses and it has worked perfectly up to now. I do like having it. It makes me feel more comfortable when people are swimming around, and gives me more control over when to flush. The tank does take up space, but the top of it forms a handy place to store things like tissues and, in this installation, a towel on the towel rack completely hides it. It seems completely foolproof and simple to use. I recommend it.
NEW AFTERMARKET LOWER UNITS