DIY Watermaker

[Bradley]

Does anyone know of good plans for building a 12 volt watermaker?

[cabo_sailor]

The January/February 2003 issue of Good Old Boat has an excellent article by a Guy Stevens on the construction of a 20 GPH water-maker for less that $2,500

also this web site was recommended by another member but I have not really checked it out:

Watermaker

[Maren]

Originally Posted by cabo_sailor

also this web site was recommended by another member but I have not really checked it out:

Watermaker

That was a really interesting site. Does anybody know what happened to the gent? He stopped posting in April of 2004.

[Latitude9.5]

I have a 40 gallon per hour built basically off of some plans you can buy on ebay (they used to be free on the guys website) it does talk about doing it 120 volt a/c, but i'm like you with the cost of diesel and the wear on the engine i would much rather have something 12 volt.

[GordMay]

Originally Posted by Maren

That was a really interesting site. Does anybody know what happened to the gent? He stopped posting in April of 2004.

Apparently, Glenn Ashmore was planning to launch “Rutu” near the end of September 2004.
He was still answering Emails as of November of 2006.
glenn@rutuonline.com
http://www.cruisersforum.com/forums/...rs-2533-2.html

[Alan Wheeler]

One of our members Louis Riel (Brent Swain) has plans for a Watermaker. I think he sells the plans, but am not sure.

[northerncat]

does anybody have a copy of the good old boat article that they could scan and post as i would be interested to read it
sean

[GordMay]

Build your own watermaker ~ by Guy Stevens
Published in "Good Old Boat" Issue: 28 - Jan/Feb 2003 (pages 16 - 23) is not among the many “GOB” articles that are available on-line; but may be ordered from the publisher at:
Good Old Boat - Back Issues

BoatUS has posted a number of “GOB” articles online:
BoatUS.com: Good Old Boat Magazine

Other “GOB” article links:
Good Old Boat - Other Article Links

[Aikiguy]

The issue is still available as a back issue you can order it from them.

12 volt is really not a very good option unless you want to design something with power recycling, such as the spectra systems, they have a lot of parts and while they have gotten a lot lot better over the years still have a failure rate far in excess of a standard high pressure pump.

You could theoretically drive a standard high pressure pump off of a 12 volt motor. There are issues that you would have to resolve involving the physics of power transfer. 120 volt AC or direct drive is easy to accomplish and will give you a robust system that can put out between 25 and 50 gallons per hour or more. Direct drive works for most small sailboats really well.

ps. Please don't scan and post my copyrighted materials, that would be tacky, and cause problems. Buy the back issue, it is like $5.00 none of which do I get from them.

Guy Stevens

[Jonesee]

Guy, very tactfully put!! I hope those that need the plans purchase them from you.

[GordMay]

WELCOME ABOARD, Guy!
Great article.

Good Old Boat - Back Issues

January/February 2003

This month we take a look at the Allied Seawind ketch sailed by Don Casey, tell of Renee's restoration, and profile the Hallberg-Rassy company. Guy Stevens builds his own watermaker, John Ditzler does a stern tube replacement, Theresa Fort turns a home sewing machine into a macho sailmaker's tool, and Ted Brewer makes you want a motorsailer. We have a lot of fun with the boat of the year contests held by other magazines, do a profile of master rigger Brion Toss, and take a look at sailing into our 70s and 80s. Chuck Campbell's photo spread of Maine is breathtaking, Barbara Wyatt chronicles a Scout dinghy refurbishing project, and John Phillips tells of the Monte J which went cruising without a crew. We tell of the third annual Good Old Boat Regatta in Annapolis, feature heaving to and making your own folding bike as Simple Solutions, and discuss a stern boarding gate and removable trailer lights as Quick and Easy projects. There's more, of course.

[svnakia]

I looked at a lot of information on building my own water maker and came to the conclusion that a 12VDC water maker is fine as long as you're ok w/ a lower capacity water maker, say around 8 gph. The thing is the amount of 12V current required to run the pressure pump. See this thread for some math:

http://www.cruisersforum.com/forums/...-hp-10979.html

Looking at it again... If you plan on using a Dow Filmtech SW30-2540 (a 2.5"x40" membrain) at 800 PSI you'll need to pump 3 GPM of sea water into it to keep the recovery under 13% (the filmtech specification).

(3GPM*800PSI)/1460 = 1.64 HP or 88 amps ar 13.8VDC

You can violate the design specifications of the membrain and pump less water through it but even at 1.5GPM you're going to need:

(1.5GPM*800)/1460 = .82 HP or 44 amps at 13.8 VDC

Notice I use 13.8 VDC instead of 12.3 VDC, a more realistic 'stand alone' battery voltage. That's because I can't imagine putting a load of 50 amps or more on my batteries for a couple hours to make water (the watermaker isn't going to be the only load). That's pretty hard work for batteries alone so I assume I'd be running the engine or generator to help out the batteries.

So, if you want a big watermaker you'd better plan on building either an engine driven unit or a AC powered unit.

Good luck!

John
S/V NAKIA
Web Log of Sailing Vessel NAKIA

[northerncat]

i was kind of hoping guy that your article was dealing with builidng a 12 v system, i would like to try building one that would make 10 l per hourand at this production rate the amps draw would not be quite so harsh
i must admit that i hadnt considered that a magazine would still have copies of a mag they printed 5 yrs ago lying around
sean

[Tellie]

Getting 10gph out of a 12V unit would be tough if you're looking at saving amps. I built my own engine driven WM awhile ago for about the price range often qouted.Along with a lot of research I bought the plans online and felt the small cost was well worth it. It can out produce any of the small 12V watermakers on the market. But if I were to do it all over I'd opt for a smaller 12V unit. Higher producing gph 12V watermakers are not for boats whose Amps have champagne wants on a beer budget. There are too many variables to say one watermaker fits all. Though I like 38gph I've found it is far more than I need and after alot more experiance now than when I started a few years ago on a watermaker quest I've learned more is not always better. Rule one is that WMs like to be run often and long, a few hours every two or three days. At 38 gph I make enough to float the boat and I just can't use that amount. A better plan is to make 4-8 gph and let the unit run a few hours every two or three days and maintain itself through use. At the lower gph rate you should be able to get a gallon of water for a little over an Amp with an energy recovery unit like a Spectra.

[Alan Wheeler]

Apart from customising an installation to suit your boat, is there a big saving to be made in building yourself?? I thought the cost was mostly the filter/membrane system.
And just how long do you get out of a membrane before it has to be replaced???