Sue is the
acknowledged master of Worst Case Scenario thinking on Cilantro. Curtis is the ranking Optimist and Enthusiast. Sue likes to establish routines and follow them; Curtis likes to add features and experiment. Usually
our tendencies balance each other out or even complement each other (and occasionally we swap roles), but at other times we collide.
On 24 February while making water in Caleta San Juanico (Gulf coast of Baja California
Sur), we had a small collision.
Making
fresh water from seawater is a complicated and expensive undertaking; the
benefit is that we can stay in remote anchorages as long as our other supplies
(including gas for the generator) hold out. Our watermaker is a SeaMaker 20
modular system purchased in 2012 from Rich Boren of Cruise RO Water in
Escondido, CA. The SeaMaker 20 includes a DC boost pump, several debris strainers and
micron-level filters, lots of tubing and valves, a control panel with flow
meter, an AC high-pressure pump, and a reverse-osmosis membrane. We use a portable Honda 2000 generator to run the high-pressure pump. We also have a handheld
salinity tester to make sure the water we produce is actually fresh and not salty.
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| Cruise RO watermaker control panel in main salon. |
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| Cruise RO pre-filters under head sink. |
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| Cruise RO Control panel and filter in main salon. |
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| Curtis during the 2012-2013 install of the Cruise RO watermaker. |
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| High pressure pump and RO membrane vessel (white horizontal tube in cabinet) in the head. |
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| "Water puppy" boost pump in the bilge. |
The basic sequence is this: start up the generator and pumps, pressurize the reverse-osmosis system, test the salinity or Total Dissolved Solids of the output water (in ppm or parts per million), and—once the ppm falls below 100—run that output water into our onboard tanks until they are full. Curtis—Mr. Curious—recently started to wonder what the salinity reading was at the end of watermaking, after the system has been running for an hour or two. The last couple of times we have checked, the ending salinity was around 60 ppm, slightly lower than the reading of 75 ppm at the start. No big deal. Today, however, Curtis’s ending salinity reading was 220 ppm! Yikes, said Sue.
(On 20 February, while monitoring our watermaking, Sue had been shocked to see the pressure gauge suddenly reach the maximum safe pressure of 950 PSI instead of 800 PSI. According to the operation manual, a surge of high pressure can cause “catastrophic failure and tearing of the [RO] membranes.” We finished our watermaking that day without incident, and Sue tried not to think worst-case-scenario thoughts.)
Now here we are, 4 days later, with a reading of 220 ppm in the sample water, after filling our tanks. 220 ppm is nowhere near the super-salinity of seawater, but...maybe we DID ruin the membrane, thought Sue, and we just filled our tanks with brackish water. Yikes indeed! Now we’ll have to super-conserve, wash dishes in salt, forgo showers, go directly to Loreto to flush out our tanks and buy water.…
Curtis didn't look too worried. He showed her the tester. Yes, it clearly read “220.” He handed her the plastic sample cup to try it herself. (Curtis has known Sue a long time.) Sue dipped the tester into the inch of water and peered at the readout. But her gaze was distracted: what are all those little swirling bits in the water? A few brown ones and a lot of shiny clear crystals at the bottom. Aha, wrong sample cup! This was a unwashed snack cup from the galley. Its most recent use? Roasted salted peanuts!
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| OOPS—not an approved water sampling cup! |
The final reading with a proper sampling cup? 60 ppm, well within limits. 😃
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| Sue testing the salinity of our output water. |
