Water maker comps

[john61ct]

Originally Posted by kenbo

If by native dc you mean 12v, then I believe your gph will be limited to about 30gph. The reason being, the largest 12vdc motor is 1hp. You may find a larger 12vdc motor but it will be a challenge to get it to drive a triplex pump at the required rpm.

Now you could get more permeate by adding an additional pressure vessel but at 800 to 900 psi your feed water flow rate will drop way below what Dow recommends and TDS will suffer.

Could going to 24V buy a significantly higher gph rate?

I definitely want to stay with standard, OTS non-proprietary components, and within their "comfort zone",

reliability and low maintenance, low ongoing cost of ownership being a lot more important to me than gph production rate.

And maybe it's worth repeating, *energy* efficiency, as in amps/gal, is completely irrelevant, to me.

[kenbo]

Originally Posted by john61ct

Could going to 24V buy a significantly higher gph rate?

I definitely want to stay with standard, OTS non-proprietary components, and within their "comfort zone",

reliability and low maintenance, low ongoing cost of ownership being a lot more important to me than gph production rate.

And maybe it's worth repeating, *energy* efficiency, as in amps/gal, is completely irrelevant, to me.

Yes 24vdc gets you up to 2hp motors. A 24vdc, 1.5hp motor should yield about 42 gph, a 24vdc, 2hp motor about 55 gph. I based this on operating at 800psi.

You can build or buy a unit that uses standard RO consumables.

The 1.5 hp motor draws 60A @ 24v and the 2 hp draws 70A @ 24v.

I seem to remember that you were considering building a DC generator using a "school bus" atlternator, hence the up to 200A reference in an earlier post. If that's still an idea and you want a high gph water maker, then I would suggest something like this https://aquamarineinc.net/aquagen.php
They can include both an alternator and clutch driven RO pump on the same unit. The gph capacities with an engine driven pump can be spectacular, over 100 gph.

[Dockhead]

Originally Posted by Paul L

For many of us we don't want to burn diesel any more than we have to, we don't want to heat our boats with excess genset or main engine heat in the tropics and we don't want to waste excess afternoon solar. As you say, for some, I assume you, you have a setup where you will be running engines for other reasons often. I just checked our gensrt hour meter. We have used 3 hrs in 3 months. Most of the rest of the juice has come from solar, as we only did a few days using the Yanmar.

Using your logic you could take it to the extreme and not waste your money on LED lighting. Just use cheap tungsten bulbs and dino juice.

Actually I think he's right and that this is sound advice. It's not like LED lighting at all, because we are not running the watermaker off batteries and for hours every day. Watermaker efficiency from compound Clark pumps and such comes at the cost of complexity and expense, very undesirable. And if you are running a watermaker off a generator, then you might actually burn MORE fuel running a more efficient but lower output watermaker, than just doing a shorter run with a bigger "dumb" watermaker. That's because diesel generators have a lot of overhead -- the first 25% of capacity costs double what the second 25% does, so the marginal kW when you're already using 50% is almost free. That's the kW you'd likely be saving with a high efficiency watermaker so I think John61 is exactly right, if you're running it off a generator.


I am in the market for a watermaker for my upcoming summer cruise, and after a lot of research and analysis, I will go super simple, large, inefficient, and dumb -- as much of a KISS watermaker as I can find -- for short, brutal, and effective watermaking sessions using my 6.5kW diesel generator or 2.5kW school bus alternator on the main engine. Such a device costs half of what a Spectra does and produces more water per hour.

Originally Posted by john61ct

Why not just get a high gph unit, and only run it when you a burning dino juice anyway?

Bingo.

[john61ct]

Originally Posted by kenbo

Yes 24vdc gets you up to 2hp motors. A 24vdc, 1.5hp motor should yield about 42 gph, a 24vdc, 2hp motor about 55 gph. I based this on operating at 800psi. The 1.5 hp motor draws 60A @ 24v and the 2 hp draws 70A @ 24v

You can build or buy a unit that uses standard RO consumables.

Excellent!

I don't know anything about electric motors, any suggestions (from anyone) on how to source one appropriate for this use, or at least what factors to look out for?

I'll talk to Rich about just substituting such a motor for the AC one in his systems,

but any other ideas on how else to proceed? I'm not inclined to research how to reinvent the wheel in a full DIY project.

Originally Posted by kenbo

I seem to remember that you were considering building a DC generator using a "school bus" atlternator, hence the up to 200A reference in an earlier post. If that's still an idea and you want a high gph water maker, then I would suggest something like this https://aquamarineinc.net/aquagen.php
They can include both an alternator and clutch driven RO pump on the same unit. The gph capacities with an engine driven pump can be spectacular, over 100 gph.

Yes Rich does sell that type too, but reckons they make for a lot of maintenance headaches.

wrt the DC genny, now looking at specialist alts, get up to outputs much higher than 200A, some even at low rpm, e.g. 400+A at 28V, 11+kW! Sure beats a mains charger fed by a little Honda 8-)

Anyway, I think I'd rather keep that and the watermaker as separate standalone units for flexibility, since I'm looking beyond just the boat.

[john61ct]

Originally Posted by Dockhead

And if you are running a watermaker off a generator, then you might actually burn MORE fuel running a more efficient but lower output watermaker, than just doing a shorter run with a bigger "dumb" watermaker.
..
so I think John61 is exactly right, if you're running it off a generator.

Thank you!

Really felt like I was banging my head against a wall, in several of these related threads.

I've been a fanatical tree-hugging greenie since the 60's, but energy efficiency is not always the be-all end-all virtue in every scenario.

The key use-case opposite poles here are:

solar only, dino-juice very rarely used: AH/gal is critical

on the one hand, vs

motor running at least a couple times a week for a few hours

on the other, where gph capacity can be a lot more important.

AC vs DC is IMO pretty irrelevant, both for the WM and the power source.

[Dockhead]

Originally Posted by john61ct

Thank you!

Really felt like I was banging my head against a wall, in several of these related threads.

I've been a fanatical tree-hugging greenie since the 60's, but energy efficiency is not always the be-all end-all virtue in every scenario.

The key use-case opposite poles here are:

solar only, dino-juice very rarely used: AH/gal is critical

on the one hand, vs

motor running at least a couple times a week for a few hours

on the other, where gph capacity can be a lot more important.

AC vs DC is IMO pretty irrelevant, both for the WM and the power source.

I think that's it exactly.

Every kw/h of electrical power doesn't have the same cost (in either dollars or kg of carbon emitted or however you want to count it). The marginal cost of a kw/h produced by main engine or generator when those machines are being used for other purposes is very small, and in some cases close to 0. If you have such power available, then bigger capacity, not bigger efficiency, makes capturing this power more effective.

And I agree with you about AC vs DC. Convert one to the other with a loss of just a few percent. I produce electrical power in both forms (230v AC from the genset, 24v DC from the school bus alternator), but I'm leaning towards an AC watermaker for the extremely banal reason (illustrating just how agnostic I am about it) that wiring the power supply will be neater with AC, and I have free AC breakers on my main panel.

[DotDun]

Originally Posted by Dockhead

I think that's it exactly.

Every kw/h of electrical power doesn't have the same cost (in either dollars or kg of carbon emitted or however you want to count it). The marginal cost of a kw/h produced by main engine or generator when those machines are being used for other purposes is very small, and in some cases close to 0. If you have such power available, then bigger capacity, not bigger efficiency, makes capturing this power more effective.

And I agree with you about AC vs DC. Convert one to the other with a loss of just a few percent. I produce electrical power in both forms (230v AC from the genset, 24v DC from the school bus alternator), but I'm leaning towards an AC watermaker for the extremely banal reason (illustrating just how agnostic I am about it) that wiring the power supply will be neater with AC, and I have free AC breakers on my main panel.

Another positive of high output WM is you don't have to continually be a water miser. Deck crusty from long salty passage? Hose it down! No problem, I can replace the water in 10 minutes while the genset is running due to laundry day tomorrow!

[Tellie]

Originally Posted by belizesailor

Unfortunately terms like "LOUD" are very subjective. It would be interesting to quantify "LOUD"...for example how many db at 1 meter...hey Tellie, do you know?

The Clark pump does make sounds, but Ive never considered then loud. Mine is mounted in the port engine room and if I stand in the aft half of that hull I can hear it, but just barely. Mounting location plays a role in how "loud".

Most quiet watermakers in the world bar none.

[Paul L]

Originally Posted by Dockhead

Actually I think he's right and that this is sound advice. It's not like LED lighting at all, because we are not running the watermaker off batteries and for hours every day. Watermaker efficiency from compound Clark pumps and such comes at the cost of complexity and expense, very undesirable. And if you are running a watermaker off a generator, then you might actually burn MORE fuel running a more efficient but lower output watermaker, than just doing a shorter run with a bigger "dumb" watermaker. That's because diesel generators have a lot of overhead -- the first 25% of capacity costs double what the second 25% does, so the marginal kW when you're already using 50% is almost free. That's the kW you'd likely be saving with a high efficiency watermaker so I think John61 is exactly right, if you're running it off a generator.

.......

For a boat and travels like you plan, a decent sized AC watermaker certainly makes sense. In your case: A boat that is dependent on it's genset for normal operations. Large tankage. Small solar availability. Dumping excess heat into the boat is a good thing. Larger crew size.

Your comments on complexity are off the mark. The complexity in watermakers where you see common problems is in the automated systems. These require many sensors plus electronics.
The Spectra Cape Horn that I used for output and a pricing example up this thread has two pumps that can be used together or singly, making a nice backup, and is a fully manual watermaker. They also allow a low power mode.

If you want a reliable watermaker then get a manual model that is sized to your usage case so that it is used every few days. Watermakers do much better when used regularly.

Originally Posted by Dockhead

....... Such a device costs half of what a Spectra does and produces more water per hour.

Why make a statement that a Spectra is double the cost when I put the actual prices above in this thread and they are not?

[Tellie]

Originally Posted by u4ea32

I agree with the opinion that Spectra pumps are too loud, as they are as loud as a diesel. So if running the engine, no big increase in racket. But way too loud to run for hours and hours. I’d still own a powerboat if I wanted that level of noise.

I agree that mounting the pump in another hull far away would help.

I have put up with the racket, but no longer.

I removed my water maker, and am waiting for new technology.

If you see or hear a Spectra as loud as the diesel then either the Spectra has serious issues or it's the most quiet diesel known to man.

[Tellie]

Originally Posted by john61ct

Could going to 24V buy a significantly higher gph rate?

I definitely want to stay with standard, OTS non-proprietary components, and within their "comfort zone",

reliability and low maintenance, low ongoing cost of ownership being a lot more important to me than gph production rate.

And maybe it's worth repeating, *energy* efficiency, as in amps/gal, is completely irrelevant, to me.

24V, 120gph at 1500Watt, more quiet than ANY plunger pump. Use your Honda2000 to run it.

[a64pilot]

Originally Posted by SSgtPitt

We’re also currently in the market for a water-maker. We’ve got a 1982 36’ Cape Dory, not a lot of room on this one with it’s narrow beam and low freeboard and there’s only two of us. No kids, no relatives, no friends, no one else but us......WhooHoo!!

We’re moving onto the boat in a few days so we can get her ready go. So our experience is limited and what we buy or do is influenced by CF and others.



I’m really leaning hard to the AC CruiseRO or the AC Rainman. I like the CRO because of the high output, no dealer specific parts, all consumables can be bought anywhere and the customer service. Plus he gives away a ton of info here on CF and actually answers the phone when you call.

The Rainman though is super portable, no hard install, so it can be offloaded very easily and taken ashore if needed and I can’t find a bad review anywhere but I also don’t want any dealer specific consumables.



I have 400w of solar in process, 2KW inverter, 450A in 4 - 6v Trojans and the Honda generator. I’m hoping to be able to use a combination of the solar/batteries/inverter and then the generator as needed when we’re using it for something else.



If this is considered “hijacking the thread”, I apologize, but we need some more experienced cruisers recommendations.

Your not hijacking, however I suggest you start your own thread.
You have most of it correct, however your not realistically running either Watermaker off of Solar, your going to do so off of your alternator or generator. Today I made 100 gls while motoring down the ICW for instance, cost me about 10% SOC from the bank, cause my 125 amp alternator can’t quite keep up as it’s only good for about 90 amps continuously

[john61ct]

Originally Posted by Tellie

Most quiet watermakers in the world bar none.

Sorry for being thick, which ones are?


Here's Hondas' specs:

60 dB(A) @ rated load 53dB(A) @ 1/4 load

right up to the eu6500is model

I can't find the reference now, but I believe that's at 7m, or about 22 feet.

Remember that dB increases exponentially, an increase of 3 db is a doubling of the noise pressure but barely detectable by humans.

10 db is 10 times as much power. A generator with a 70dba noise level will sound about twice as loud as one with a 60 dba rating. But the noise will seem to carry 10 times further.


It sure would be great to get comparisons between the different WMs.

[john61ct]

Originally Posted by Tellie

24V, 120gph at 1500Watt, more quiet than ANY plunger pump. Use your Honda2000 to run it.

Sorry but I don't know enough to understand what watermaker make or model you're referring to here, nor have I ever heard of a "plunger pump".

I don't plan to have any AC at all except when (very rarely) at a marina.

If some AC device proves to be mission-critical, I'd also need to purchase an appropriate inverter to run it.

[Tellie]

Originally Posted by john61ct

Sorry for being thick, which ones are?


Here's Hondas' specs:

60 dB(A) @ rated load 53dB(A) @ 1/4 load

right up to the eu6500is model

I can't find the reference now, but I believe that's at 7m, or about 22 feet.

Remember that dB increases exponentially, an increase of 3 db is a doubling of the noise pressure but barely detectable by humans.

10 db is 10 times as much power. A generator with a 70dba noise level will sound about twice as loud as one with a 60 dba rating. But the noise will seem to carry 10 times further.


It sure would be great to get comparisons between the different WMs.

Spectra watermakers. Not the generator.