We went with the Spectra Cape Horn 330. This WM has two electric 12V pump/filter units and a 48" membrane with Clark Pump for boosting the pressure. You can run both 12V pumps for about 15 gallons per hour of fresh water output using about 16 watts of 12VDC power (or about 1.4 amps) per gallon produced, or just one 12V pump for half the output. I also like the back-up that two independent pumps provides.
On most days we are not using all of our solar output midday. The house bank is charged up by 11am or so at our current latitude- even earlier in the summer. At that point we are just floating along with 50-60 amps of DC solar power to spare, until the sun starts going down and our use starts to exceed the solar output again. So we have lots of extra power available to make water through the middle part of the day without draining the house battery bank. Also, when underway with alternator cranking there is usually plenty of output available. If we take advantage of these high output scenarios for making water, I don't see any major effect on our power reserves vs consumption.
Everything came nicely packed in one big (heavy) box:
Now that I am most of the way through the install, I can say that I am very impressed with the detail provided in all the parts bags and instructions. They really include just about all the little bits and pieces you need for the installation. Of course I couldn't help doing a little customizing...
The different modules come loose, which gives a lot of flexibility on installation (vs one big frame mounted package). I spent a couple of weeks puzzling over where to fit all the components. I decided to mount the pump/pre-filter modules in the ER and the membrane/Clark Pump assembly below deck in the companionway just outside the ER (the membrane does not perform well in hot spaces).
The Clark Pump is a dual acting piston pump that boosts pressure coming out of the DC pumps to the higher pressures needed for the membrane filter to separate the salt out of the feed water. Hanging this heavy assembly in the below deck space was a little tricky, but the addition of an isolation mounted aluminum plate to hang the unit from made things a little easier to hang in place below the deck, and clear of any interferences:
The rest of the components (2 pump/pre-filter modules, control panel, accumulator tank, etc.) required a lot of custom brackets but was pretty straightforward:
There is lots of plumbing between components but nothing too complicated. They use a combination of braided vinyl water hose and push-to-connect plastic tubing- all good quality stuff. I added some fittings and valves to customize the install a bit. The feed water supply for the water maker came off the existing seachest that supplies the anchor washdown pump and shaft seal flushing feed.
Seawater supply valve and secondary strainer:
Brine water discharge from the WM goes to the flanged overboard fitting:
Installed a new accumulator tank for the fresh water system while I was in the neighborhood:
Also cleaned up the fresh water tank supply manifold plumbing and valves:
Fresh water flushing valve for cleaning the WM filters after use:
WM pump breakers, tank fill distribution manifold, pump/filter modules:
Running 3/8" tubing from the WM to the water tanks:
So that's the bulk of the work. I still have a few tubing connections to make at the tanks and the pressure and flow gauges- probably a few hours more to get these done. The water in the Bay has a lot of suspended sediment, plankton, and other little stuff that could clog up the system pretty quick. Testing will have to wait until we take a test run outside the Golden Gate in some nice clean ocean water.
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