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Old 11-08-2008, 04:49   #1

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Water makers - mains or 12 bolt?

I have to spec the water maker for the new SF 50 boat and I am thinking of using a 220 volt ac mains model as opposed to the 12 volt models. Turn on tye gene once a day and have done with the water. I understand that the mains one is much faster at making water.

What are the views of the forum on which type is best?
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Old 11-08-2008, 09:05   #2
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I suggest you first plan your "house" power system then select the watermaker accordingly. I had 2 x 25kw 220VDC gensets and therefore planned all my usage around that. I had 220 VDC oven, stove tops, 40 gal/hr watermaker, etc. and tried to run as many items as possible at once for efficiency.

Next time I plan to have about a 5kw 24vdc "house" genset and appropriate sized battery bank and inverters. The genset programmed to turn on as needed to keep the batteries charged and help with larger loads. The watermaker will be a 12 or 24 vdc low volume efficient model programmed to turn on as needed and possibly run 4 or 5 hours daily. Over all I believe this setup will be more efficient than my last setup and certainly more convenient.
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Old 11-08-2008, 09:37   #3
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I believe you are coming at this from the wrong end. You need to spec how much water you want to make. You then need to understand that a watermaker that is run infrequently, probably will not work, whereas one that is run frequently does (or at least is more likely too). From that you can see if it is better to run the gennie (if the ac is on!!!!) to also make water, or whether it is a better bet to avoid running the gennie and have a 12v system run from the solar panels (i.e. making less per hour and running longer).

There is a post on this forum somewhere from a person who overspecced the watermaker, and was commenting on exactly this problem.
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Old 11-08-2008, 11:25   #4
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I believe Talbot is correct. You need to find out how much water you really use first. When it comes to watermakers many times less is more. Watermakers need to be run often to stay healthy. I built a 40gph unit on my 38' Cat and I make far more than I can use because it needs to be run often. I later added a 6-8gph Spectra and have since pickled the home built unit and haven't run it in months. The smaller unit provides all our needs. Running a watermaker everyday like you suggest seems like alot. I'd opt for a smaller 12V system with automatic run times, making water and flushing itself. Watermakers are enough work to maintain as it is, going bigger can just compound that work (and cost) needlessly. Because I have a stake in one particular make of watermaker I can't tell you here which one to choose. But my advice is a bit smaller with automatic run capabilities.
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Old 11-08-2008, 11:56   #5
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When we were originally thinking this over, I was thinking the same as you: a high capacity AC driven unit. Well, we ended up going in a different direction and the boat we bought already had a Spectra Newport 800 (16 gph, 12 volt). I was suspicious about it, particularly about Spectra's habit of using lots of proprietary parts, expensively priced.

Well, after a cruising year of experience with it, I'm really happy with it. The other comments about them being happier when run often is spot on. Plus, when we've been places where the water was brackish and muddy (and I didn't want to run it), the autoflush feature is very, very nice. Keeps the watermaker happy without having to pickle it. Not only is pickling a hassle, every time you do it, you're doing slight, though accumulating damage to the membrane.

The energy consumption of the 12 volt Spectra is quite reasonable. We also thought that we'd just run the gennie and take care of all those high power needs at the same time. Turns out we didn't do that nearly as often as we thought we would. But, the solar panels did enough to pretty much keep up with those needs and then, we didn't have to use the diesel or put up with the noise. Also, if you do go with an autoflushing model (which I recommend) it will take care of itself even when you're off the boat, so long as it has both enough power and enough water in your tanks to do the flush. Mine takes 6 gallons per flush. We've been off the boat for as long as 3 weeks and the autoflush kept everything OK.

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Old 11-08-2008, 13:56   #6

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I have had the auto flushing model in the past and would have no other type.

What capacity options are there with the 12 volt models?
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Old 11-08-2008, 14:05   #7
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We have a 120VAC Sea Recovery 33 GPH water maker on Dulcinea our caliber 47LRC. We run it every couple of days and when we do laundry (we also have a washer dryer on board). We always back flush after every use, and haven't had any problems other than standard maintenance in 9 years. We have a 5kw genset which handles the load just fine. We have had a wonderful "water" experience with this set up.
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Old 12-08-2008, 12:10   #8
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Here is a part of the Survey/test from ARC 2007 just the part concerning water makers.

Spectra got the best comments and so on I think...

Spectra Watermachines - Clark Pump is World's Most Efficient Marine Watermaker

one other producer little wonder series watermakers information
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The answer is out there !!!
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