12 volt watermakers, which one?

[newhaul]

Originally Posted by Tellie

Another common misunderstanding is that we are evil competitors with each other. Nothing could be further from the truth.

So not competitors conspirators?

[Tellie]

Originally Posted by newhaul

So not competitors conspirators?

Shhhhhh.

[senormechanico]

Originally Posted by Tellie

AGREED, and I sell them (rarely). It would be a rare case where someone started out wanting a Power Survivor of any size that I don't walk them right into at the least a Ventura 150. A slight bit more in cost up front but a far superior watermaker for todays needs.

Someone ought to pin a medal on you for doing that, if they haven't already.

[sailjumanji]

Originally Posted by Tellie

Please, spend the difference for a Ventura 150. You'll get twice the watermaker for half the energy per gallon made and a system that is easier to work on in the field.

And in my experience, the Spectra is a much quieter unit.

[c.spots]

Before you can answer the question of which watermaker is best or better, we need to know where you intend to cruise, and for how long. -Amount of rain, availability of water, availability of spares, and expertise. Is the watermaker a convenience or a necessity? Do you frequently run an engine, or do you want to “cut the cord”? Do you mind conserving water? Do you have a rain awning?
If you will run an engine frequently, it makes sense to save money and get a very high output A/C unit.
The further you plan to cruise, the more isolated the locations, the longer the time, the more you want to “cut the cord”, the more important a 12v unit becomes. There are many ways to supply 12v, not so for A/C.
When you consider the energy efficiency and reliability desired for such cruising, it becomes important to make your budget fit the purchase of a Spectra. Decrease cost and increase reliability by avoiding automatic devices - just not needed.
I have had a Cape Horn X for 10 years. Install it yourself so you know it is done right, and you will learn how it all works. Installation isn’t rocket science.
There is tremendous safety in redundancy. If one pump fails, use the other. Not enough power to run both pumps? Just run one. Lots of solar, or running an engine? Run both pumps.
Crossing the Pacific, there was a year I didn’t need it, and it was stored in PG antifreeze. (I also have a large rain awning and can fill a 100 gallon water tank in 20 minutes in a tropical down pour.). But in places, there has been no rain for many weeks, and no readily available water ashore either. It was no problem, even when a feed pump failed after 10 years.
If you only want to stay close to home just get bigger water tanks or lots of jerry cans.
And shame on those who promote the silly idea that drinking water is supposed to be a significant source of minerals. (But there is nothing wrong with adding a tiny amount of seawater to your cooking.)

[Summerdreams]

Originally Posted by Sojourn2

We have had two Dessalator watermakers in our two Beneteau's.
60 litres per hour...rugged reliable...fantastic

We have tried for 4 hours to get our Dessalator Duo 100 working.
New boat and trying to understand everything.
We have primed unit with about 50litres of water and then turned on unit, it only works on 12dc.
Then the Dessalator only works on 220 system.

Any help is appreciated.

[contrail]

Originally Posted by belizesailor

All my Spectra Catalina components are mounted up high in the port engine room...consumed zero otherwise usable space.

Only the control panel is out at the nav station.

Oooo, watermaker in the engine room always makes me nervous, due to personal experience. On two occasions, my system (Spectra, otherwise a great system) has sprung a leak in the tubing or expansion tank, and in both cases, there was a fine salt spray covering almost everything! Quick rinsing and thorough cleaning saved the day (and the engine and other gear), but I am still mulling putting some sort of protective shielding between the watermaker and everything else. Please note, the leaks were NOT anything Spectra related, but they were in top quality gear, installed correctly and well. When I managed a 50,000 GPD commercial system, using AC driven Cat Pumps, on a couple of occasions we had one of the little caps on the pump fly off with the force of a bullet.



The point being, remember that water, with 800 PSI behind it, has a lot of force, and if it's salt water, can get things quite wet! The watermaker is best in it's own compartment, if possible, or at least away from things that salt water might ruin.

[belizesailor]

Yes, leaks are a potential issue, but over the 14 years that Ive had it installed there Ive only ever had minor leak issues. Im pretty picky about the state of the engine compartments so any spray or leaks get dealt with promptly.

A spray sheild out of acrylic would be easy to do...esp since in my instalation it would not need to be formed, just a flat sheet would work.

[thaisail]

Anyone who knows where I can get a new membrane for a power survivor 40E water maker? Do I have to by a Katadyn membrane or will a generic membrane be Ok to use?

[Pizzazz]

Here is some thoughts on 12V watermakers and a reference to a 1998 article that measured exact power consumption and output.

You need to drive certain gpm through a membrane at 800 psi to produce water. Most standard 12V watermakers use 1/3 hp motor (some even go as low as 1/4 hp) to drive approx. 1/3 gpm through a 2521 (21") membrane achieving around 30% recovery (hence the output is typically stated at around 6 gph, which is 30% x 1/3 gpm x 60 min/h = 6 gph).

The net power required to drive 20 gph at 800 psi (for 6 gph product) is approx. 115W or 1/7 hp or 9A at 12.5V. On top of this we need to add the pump efficiency and the DC motor efficiency. Plunger pumps typically run at 87% efficiency, while small DC motors run at around 50-60% efficiency, thus the electric power is double the mechanical power required. Thus, we are talking about 1/4 hp or 1/3 hp motors.

Clearly, there is a trade-off here, and the best way to improve water maker efficiency and output is to select an efficient motor or a high efficiency pump (i.e. Spectra). There is a cost associated with this, where an efficient brushless motor can be 5x more expensive than a standard 12V dc motor (similar physics to the alternators discussion).

Then, I found a company called PumpTec that makes a stainless steel pump/motor combination for misting applications. They use a 1/7 hp motor, approx. 50% efficient and their pump is close to 96% efficient according to the vendor. I have been running some tests on the pump with different cams and the best I can do is approx. 0.24 gpm total flow at 800 psi. The cost is reasonable, <$300 for the motor/pump combo and it is very light and quiet, it has this pleasant noise when it is running that can be totally ignored. Further, it does not need a feed pump.

The question now is do I pair this with a 2514 membrane (half of the size of the 2521 which is used by most 12V watermaker vendors at 0.33 gpm) or do I go for the larger membrane? I know the smaller membrane will work, my question is am I leaving some potential product output on the table by not selecting the larger membrane?

A couple of other considerations, both the 14" and the 21" membranes cost the same ($200) and the pressure vessels are of similar cost. I am not worried about membrane lifetime at these price levels. The cost of pickling a watermaker is close to $100, I might as well just replace the membrane every year or so. I also noticed that some cruisers are running their watermakers at lower pressure, close to 600 psi, to get more output with acceptable water quality. Frankly, if you are washing dishes and showering, you do not really care if it is 400 TDS or 200 TDS. I can easily get to 0.33 gpm with the above setup if I keep the pressure around 600 psi. Also, I believe Spectra runs at 600 psi as well, with standard membranes.

Any thoughts?

https://www.practical-sailor.com/iss...es/4384-1.html

Pump Motor Set, 116C-075/M8215, 12V, BUNA, M-VALVE, 6 - 1/4" PORTS, SS PUMP

[Paul L]

Originally Posted by Pizzazz

........ The cost of pickling a watermaker is close to $100, I might as well just replace the membrane every year or so.......

Huh, it is at most a few dollars per time on the watermakers I've pickled.

[newhaul]

Originally Posted by Pizzazz

The cost of pickling a watermaker is close to $100, I might as well just replace the membrane every year or so.

Any thoughts?

]

actually yes why does it cost you a hundred bucks to pickle your watermaker ?
Mine costs less than $5 to pickle plus the 15 minutes time.
https://www.walmart.com/ip/Super-Tec...waAnioEALw_wcB

And a gallon is enough to do my watermaker 3 times.

[briblack]

looks like a very interesting pump. have you made a working unit with it yet?

[Pizzazz]

Originally Posted by Paul L

Huh, it is at most a few dollars per time on the watermakers I've pickled.

I meant to say cleaning the water maker. Usually it happens in a remote place, and you buy the solutions from an expensive marine store, last time it was Eur 86. My point is that there is a trade-off between maintaining the watermaker and ease of use. I run my current watermaker (Power Survivor 35) every couple of weeks and never pickle it, it still produces 175-180 TDS after three years. If I do not replace it, I will definitely replace the membrane before a longer cruise. Then I looked at the cost of replacing the proprietary membrane and it seems that I can put together a working solution with 3x the output, same efficiency, cheaper membranes for $500-600 total cost. With a proper sized, totally enclosed continuous duty motor, stainless steel pump and all the bells and whistles.

[Pizzazz]

Originally Posted by briblack

looks like a very interesting pump. have you made a working unit with it yet?

I am currently testing the pump before I get the membrane. I have let it run for 24 hours continuous, no issues. I am getting 0.21 gpm flow at 13.2A at 800 psi and 0.26 gpm at 600 psi, pretty much in line with the spec sheet on the web site. Based on my calculations, this should be good enough for 3.5 to 4.0 gph product water. All I need is to order a membrane and I am debating on the size.

The pump seems to be ideal. The company also said that they may assist us with different sized motors (the pump max flow rate is 0.42 gpm if it had a stronger motor, good enough for 8 gph) if there is enough volume. Ideally, this should become a self-contained, modular, 4 gph watermaker with a target price less than $1,000 retail. The real benefits are very low and pleasant noise, it just purs, tiny size, easy installation.

SV Pizzazz