Water in the Pacific

[john61ct]

Running fewer hours per week is a great thing when living on the hook.

[fgd3]

I'd like to have a high output water maker that I could run for just an hour a day, but my boat's 12V system only produces 4-6 amps. I can still run my PowerSurvivor 35 and get about a gallon an hour. I can run it for several hours if necessary. But I just don't have the power available on board to run a bigger water maker.


Fabbian

[john61ct]

Even from an upgraded alternator in future?

[lizardofoz]

Originally Posted by owly

Watermakers use the same basic pump design as a pressure washer. For anybody who's interested, the math is pretty simple. Horsepower required equals pressure in PSI times flow in gallons per minute, all over the constant 1710. One horsepower equals 745.7 watts. There is absolutely no reason under the sun that a specific pump volume needs to be used to feed the membranes of a watermaker. Pump and belting can easily be set up to match the power available. It makes sense to size and belt your pump to match the solar power you can generate. There is no rocket science involved, just a pump pushing prefiltered seawater through a membrane at about 800 to 1000 psi. A simple valve system allows you to run fresh water through the pump and reverse the flow to flush the system afterwards. It makes sense to build your own as you can fit it to available and convenient spaces.

H.W.

Hello HW,The HP pumps do not like running under a specified RPM or run to fast so there is a window of adjustment only. I would be interested as you have recommended that people build their own so they have regular components in there that can be sourced from the manufacturer rather than the " company that assembles them and calls them their own" Have you done this yourself? Had a good result? I am interested to know the cost of setting up a RO system. I have done this many years go with components myself. To far back to remember exactly but i could estimate. Be interested to see how someone else did it. Good for all the people viewing to also know.

I bought a Cat pump for my home made kit. Had a local shop make up a pressure guage and flow meter arrangement. Bought local HP housings made in Thailand and imported membranes 40" long and had a local hydraulic shop make up the HP hose same as they use for diving compressors. Mine was run of a clutch of one of my main engines

[lizardofoz]

Originally Posted by john61ct

Even from an upgraded alternator in future?

Possible or just buy a Honda portable generator and a Victron energyh charger with 3000W inverter and run a big 230VAC system off that. Direct from the inverter side with power from the generator. Then your not plundering your batteries.

Bob

[Paul L]

Originally Posted by john61ct

Unless solar is a small fraction of your overall energy produced.

Personally, I only want to run the watermaker while my ICE power sources are also running, and if that can be kept under 6 hours a week, that would be ideal.

So 40+ gph (actual fresh water produced) would work better for me, and neither noise level nor energy efficiency is a consideration for me in choosing a watermaker.

Nice to hear your change of heart, you no longer believe in your argument posted so many times that noise was the big reason to run a shorter time.
So you have determined that you need 240 gals a week. Thats a ton of water, even for a couple. Is this from your actual cruising experience? How many people?

[john61ct]

No, the noise is no longer an issue because I now plan to only run it concurrently with an ICE charge source, never in normal usage from a battery bank.

And I did state **under** six hours.

[SV THIRD DAY]

Originally Posted by Tellie

Oh brother. You could possible weld a prop shaft to a bicycle rig and push your boat around a marina as well. You'd be the only one but I suppose it could be done, but why.

Oh oh....Tellie is starting to sound like me....:O

[Paul L]

Originally Posted by john61ct

No, the noise is no longer an issue because I now plan to only run it concurrently with an ICE charge source, never in normal usage from a battery bank.

And I did state **under** six hours.

So how many gals per week for how many people with your 40+gph unit?

[a64pilot]

Originally Posted by Paul L

So how many gals per week for how many people with your 40+gph unit?

I think he’s stuck on 40, for the same reason I initially was.
Cause for almost exactly the same footprint and for not a whole lot of money it seems you can have a 40 gph Watermaker of the relatively inexpensive ones, just if you want to run it off of a Honda 2000, your at 30 GPH.
Reason is the standard 40” membrane makes 20 GPH, so if you have two membranes, 40 GPH, three 60 etc.
Just with a 1 HP motor running a standard high pressure pump your restricted to 30 GPH due to a good, efficient AC motor pulls 1100 Watts, it take a 1.5 HP motor to get the full 40 GPH, and that exceeds the little Honda’s capability.

Now of course a Spectra can blow away these energy consumption figures, they are only valid for a simple piston pump and a relatively efficient AC motor.

Rich talked me back down from a 40 to a 30, and as how he is the manufacturer, I went with his advice, and am glad now that I did, cause I can run the 30 off of a Honda, my built in gen, or my alternator, but I think the 40 would have been tied to my built in, I have an inverter that could handle it, but the alternator couldn’t make enough power continuously, meaning of course I would be discharging the bank even with the alt maxed out.

Plus even with the 30 my built in is busting a gut to charge hard and make water, I have to power manage the first hour of charging and watermaking.

[lizardofoz]

The Rainman that produces 140LPH / 37GPH runs off its own 1000W Honda motor. Or the 230VAC/115VAC model will run easily of a 2000W Honda genset and after starting the genset can go into economy mode setting. That same genset can be multipurpose after running the RO system. Can be backed up to a Victron Energy inverter charger of 3000W capacity and 120Amp charging capacity. I would be interested in what the Spectra cost to buy - the 30G model. A Rainman 230VAC system for 140LPH/37GPH is 5130US$/ 7080AUD$ Tax paid ex Sydney Australia. You are able to source virtually all the parts the system is made up from and any manufacturer's labels have been left on such things as the HP pump so you can go to WM Pumps USA for spares. Lift pump impeller is a Jasco standard. There are no unique parts that have to be purchased from the manufacturer at extremely high prices. This is a fix in the field RO system pretty well. A lot we sold to the USA for Florida and areas where the hurricanes hit. That many that production had difficulty keeping up. I wonder how many spectra's were bought by emergency services for that purpose. Of course the 1KVA Honda petrol driven model was the one they purchased due to all the power being out.

[john61ct]

Yes, even if I only need 60gal a week, I still want it produced quickly.

Obviously the 40gph is an arbitrary max rating, as with alternators, rarely actually reached.

In fact, a 30gph system will likely do me just as well, if I use 300gal in a week, just need to run the ICE power a bit longer or more often.

I was simply making the point that the desire for **energy** efficiency, just like the desire for quiet operation,

is based on a set of assumptions wrt the use case, that owner, that specific boat.

There is no set of universal conditions that dictate the same decision factors as important to everyone.

Except issues like reliability, easily getting replacement parts and filters at reasonable prices, quality of ongoing vendor support after the sale, etc

[lizardofoz]

Except issues like reliability, easily getting replacement parts and filters at reasonable prices, quality of ongoing vendor support after the sale, etc.
Yes to all of those with the Rainman brand and also price is a important factor. Also simplicity is also a important factor. Unlike other manufacturers Rainman have all their prices and replacement parts prices on the website and a estimated price landed in other countries including freight duty and local tax.
They tick all the boxes

[westsailwill]

Originally Posted by john61ct

Running fewer hours per week is a great thing when living on the hook.

Bingo! We went from a Little Wonder that gave 5.5-6gph to a unit I built powered By a Honda 2000 that puts out a consistent 20gph. We went from budgeting our daily ration of 6 gallons per day, to whatever we feel like using, and will be adding a second 40” membrane to increase output to 30gph. The ability to keep your boat and gear salt free, as well as being able to shower as frequently as you desire are a major plus. We are currently running the watermaker three times a week for 2 hour, giving us approx 140 gallons per week. The additional membrane, which by the way, uses no more energy than the single membrane, will allow us to run the Honda just twice a week. It sure beats slaving over the Little Wonder. For us it has been a win win. It all about choices, and to each their own.
Cheers,
Will

[lizardofoz]

Little Wonder ROs are good units. Well done. I had forgotten about them.