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Old 03-09-2010, 23:11   #1
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Watermaker - 12vdc, 220vac, or Engine-Driven

I am currently looking for a water maker but given the high current drawn I am tempted to go for the high pressure pump that is driven by V-belt from the main engine. (Ech2otec) During voyages I will run the motor every 3 or 4 days for a couple of hours - have 1000l (~ 200 gallon) of fresh water storage. I have solar panels , invertor and my wind generator is ordered but still think of maximising efficiency when the engine is running - charge batteries , make water , do washing , have hot shower etc all in the couple of hours every few days. Anyone with experience of these mechnical drive types and the things to watch out for ?

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Old 03-09-2010, 23:33   #2
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They don't all draw high current..there a re a lot of posts on here about this.
3rd generation watermakers give the best output per amp...I have a Schenker that produces 35litres per hour for a current draw of only 8-9 Amps. I run it every day when I run the engine for 90 minutes which produces :
50 litres of fresh water
Heats the hot water cylinder
Keeps the freezer down below -20degC
fully charges my 420Ah AGM battery bank
I don't have solar panels or a wind generator
You have to run yoiur engine why not go with a super efficient watermaker rather then a simplistic 1st generation unit ?

See you out there ....... Alan S.V. Elyse
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Old 04-09-2010, 04:38   #3
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do not recommend belt driven

We had a belt driven WM over the last 4 years and it has caused more problems and cost more than a 12V one would have, so we are in the process of converting it to DC now.
I would strongly recommend to go for a DC system.
Belt driven system problems include:
- cost of mounting it on the engine (almost $1000 when all was said and done after the first one in Aluminum broke. Note that the HP pump is very heavy)
- damage (or wear) to the engine
- can't use it while under way (too restricted rpm range)
- Have to run the engine specially for the WM

Can't comment yet on the DC system, we should have it up and running in a few days.
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Old 04-09-2010, 06:31   #4
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I've got a PUR-40 that makes about 1.5gph@4A. Their 80gpd model takes around 9A, iirc. I try to conserve water and collect it when it's available and cheap.

I've got engine driven refrigeration and don't have another belt slot for a water maker high pressure pump. I'm trying to avoid running the engine so the 12VDC version is what works for me.

The type of water maker would be dictated by the water and power requirements you have I think. If you're going to run the engine to recharge batteries/refrigeration/water maker and have the PTO/belt space, you might be better off especially if you use a lot of water.
Capt. Douglas Abbott
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Old 04-09-2010, 06:45   #5
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I built our's and it is engine driven, and has worked flawlessly. The only problem we have is it is designed for low RPM, (1800-2000), and if you go over that rpm it tends to draw a vacuum. It is nice to charge everything and make water while heading to the next anchorage
Denny and Diane
Lagoon 37
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Old 04-09-2010, 08:32   #6
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If you are planning on offshore cruising, consider a 12V system. The redundancy of the power source is a good safety factor. If your engine, generator, or inverter fail..... Most of us have several ways to get 12V power. I like the Cape Horn extreme, since it is energy efficient, and has pump redundancy too.
Don't bother with the added expense, complexity, and unreliability of an automated unit. A rain catchment can get you free water, but isn't reliable in most places.
If you insist on a long hot fresh water shower every day, consider a 110 unit, and maybe get a genset (or two cheap gas ones, so you have a spare?) and/or a spare inverter.
I prefer to cut the cord, and can produce 18 gallons an hour with power from my solar panels.
Robert W.

Life shouldn't be a race to the finish line - enjoy the journey.
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Old 05-09-2010, 09:30   #7
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This thread has me excited me to look into building one. Of course, it will be a winter project. I will be back with many questions as I learn and search out information from those who already experienced the thrill of building their own. Mine will operate from my generator via AC.

More later in a new thread so I don't hijack this one.

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Old 05-09-2010, 09:48   #8
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If you're looking for efficiency (liters/amp-hour of electricity) then it's hard to beat the 12-volt units that recycle the high pressure water from the membrane. (If you have a gen-set, then you're probably looking more for best $ for however many liters/hour you need.)

One thing many folks new to watermakers don't realize is that watermakers like to be run every day, especially in the tropics. You can run them just to flush them, but they want to be run.

FWIW, I've been using an old Spectra 200 that I upgraded myself to a 380 (by adding a 2nd pump). Been running it for 9 years now. It hasn't been trouble free (few watermakers are) but it's worked for us & our 2 teens. We usually run it for ~2 hours after the solar panels have brought the batteries up & the charge controller is starting to regulate.

I've posted an article on watermakers in our Cruiser Information section of our website (direct link here).
-- Jon Hacking s/v Ocelot
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Old 05-09-2010, 11:11   #9
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We have been VERY happy with our Spectra Catalina model unit. We have 3 ways to generate 12 V DC so really enjoy the flexibility with this system. It produces 10-12 gallons per hour, depending on water temp, salinity, and battery voltage and draws 15-17 amps. On a sunny day, our solar panels provide enough charge to offset that current draw (provided the wife isn't making ice). With just the two of us aboard, we run it 3-4 hours about every 3-4 days and have plenty of water for drinking, washing dishes, fresh water flushes of the Vacuflush toilets, and showers. Although not the norm, we have gone weeks at anchor in sunny weather without needing to start the auxiliary generator or main engine.
Formerly on S/V Yachtsman's Dream
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Old 05-09-2010, 12:13   #10
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The fewer liquid-filled things attached to my engine, the easier I rest. The vibration isnt good for them.
Healer52 / Lisa, Rick and Angel the Salty Dog
Currently on the hard, looking for a boat
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Old 05-09-2010, 15:14   #11

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If you are motoring anyway, why would you bother with the huge complexity of electrics? Converting energy into an alternator with a loss, then battery juice, with a loss, then into a motor , again with a loss. Nothing simpler and easier to repair than a belt drive. A friend who builds watermakers, says electric drives are the main source of problems. I built my own engine driven 540 GPD watermaker for around $750. No problems.
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Old 05-09-2010, 16:05   #12
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I installed a Katadyn 160 watermaker five years ago. Easy to install. Modular. No electronics to go wrong. Draws about 8A, and produces 30 litres an hour. Run it almost every day and am still on the original membrane. Its a good piece of kit. I was advised (by Katadyn) not to mount it in the engine compartment due to ambient temperature. Makes a fair bit of noise though.
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Old 16-09-2010, 13:10   #13
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My DH installed a Katydyn 80 last weekend. The pump is HEAVY!! I strongly recommend cutting out a cardboard template when you are planning out the install. (It's a lot easier on you than trying to hold the damn thing in place while he figures out where the membrane should go and which drill bit he's going to use.) You can just tape the template in place and then finish laying out the other pieces and drilling your pilot holes. I thought it was a brilliant idea.
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Old 16-09-2010, 13:35   #14
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Originally Posted by sobriyah View Post
I installed a Katadyn 160 watermaker...Draws about 8A, and produces 30 litres an hour
Katadyn datasheet claims 29 l/h max (8 g/h) at 18A@12V (12A@24V) producing 500ppm (avg) water. That's at the limit of what can be called freshwater. Does it taste a bit salty?
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Old 16-09-2010, 14:27   #15
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Says salt water rejection is 98.4%, isn't that enough?

Think he missed typed 8 instead of 18 ah which might be more realistic.


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