Holding tanks… Ohhhhh yeah, the bane of every boat owner. Shit and forget. That’s the policy. Until things break, of course. And then, that’s when the “shit hits the fan…” (quite literally so to speak, from experience).
We have a cute little arrangement here on “Ramble On”. Like the other 500+ Tayana 37’s floating about the globe, we have a paltry 16 gallons (+/-) of holding tank capacity tucked neatly back in the bilge, directly underneath the Perkins 4-108 diesel power plant, where no one in his right mind would dare to venture. Luckily for us, I’m in my right mind only half the time, so working on the holding tank suits me just fine. I grew up working for my Dad’s plumbing company doing the icky stuff, so I only become slightly gagged out when dealing with sewage. The poo tank is glassed into the bilge, and there’s no way (unless you’re Superman with x-ray vision) to tell just how much “black water” is inside. It’s pretty much been a guessing game since we started using the head on a daily basis.
At one point, we entertained the idea of abandoning the old tank and installing a new, larger polyethylene unit. Problem is that stowage has been so well engineered into these boats (i.e. wastewater was a complete afterthought), there’s no place to put it without sacrificing a loss somewhere else. With exception to the one and only “spill” into the bilge, we’ve “ball parked” that we can go roughly 2 weeks between pump-outs. This boat was a rat’s nest of colorful wires and hoses when we got her, and nothing made any sense. I feel that we’ve been fortunate enough have the opportunity to rip the majority of the plumbing and electrical out and start over again from scratch. That’s pretty much what we’ve been working on the past 15 months, and happy to say, things are going well so far. It’s like a clean slate. It’s our boat and our home, and we now know exactly where every single hose, wire, fitting, and connector starts and ends, and what it’s supposed to do when it gets there. We also know how each system functions, and how to fix it when it doesn’t. But, it drives me absolutely crazy not knowing how full my holding tank is.
We re-plumbed the waste systems last year, including the installation of a new head, hoses, and tank fittings, but up until now we never knew how much “liquid” we were carrying around with us. Recently I purchased the SCAD Marine Solo holding tank monitor with high-water alarm. It reads the tank level externally through two foil strips and continually measures capacitance between the two based on the conductivity of the liquid level inside. No internal float switches or dip tubes to become fouled with human waste and quit working. Or worse yet, require periodic maintenance. It’s magic, with a little Science mixed in… Once calibrated at full & empty, it automatically reports with the push of a button the existing (and thusly, the remaining) tank capacity at 1/4-tank increments. We haven’t reached that point yet, but it also incorporates a red light and an annoying buzzer that turn on in the event of a “full-tank” reading. Let’s hope we don’t end up there again… Anyway, I got the thing installed this week and so far so good. Based on our estimated toilet usage to date, it seems to be pretty much on par with what we already know about our tank capacity. I still need to calibrate the high & low water level (just before, and immediately following getting pumped out), but that’s a simple procedure. At least this way, no more holding my water and running up to the marina restrooms in anticipation of pump-out day. In the immortal words of my good friend I. P. Freely, I now know exactly how “full of shit” we are.