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Old 25-11-2019, 03:23   #1
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Playing with some Numbers - Cost of Making Water

Continuing on from the cost of generating power -
http://www.cruisersforum.com/forums/...st-226160.html

What about the cost of consuming it to make water.

Now - comparing any of these costs is tough, because we have to factor in Time Based and Use Based cost. Very tough to do.
So they all depend on your use case.

I'm assuming liveaboard all year.

To use this
First - look at your L/Day Columns (2)
Left is worst case running a low / medium loaded generator
Right is best case running solar where you consume what you generate
So that tells you how much extra you are paying each year vs the best case.
Next - compare the Cost to Run each year of the different watermakers, and you can decide the extra efficiency is worth paying for.

Numbers are from manufacturers websites.

If my math is wrong please tell me.

My conclusions
- I think some manufacturers data is incorrect.
- 3 to 5 x energy efficiency difference / litre
- If you have space, add solar just for water. Don't expand batteries
- It's cheaper to add solar than to buy a more efficient watermaker
- You'll need to size the unit to Sun Hours. I havn't added that math. You can't get 500L in Sun Hours from a 50L/Hr unit. If you add battery cycles, the math changes.
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Old 25-11-2019, 03:32   #2
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Re: Playing with some Numbers - Cost of Making Water

Excel to hack with
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Old 25-11-2019, 05:52   #3
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Re: Playing with some Numbers - Cost of Making Water

On a good solar day I can run my Spectra Catalina 300 off nothing but solar for a couple of hours and still end the day with a nearly full SOC house bank. Hard cost of generating power and making water = $0.

Amortized cost per liter is also low given the service life of the water maker and the solar panels. I installed my Spectra in 2004 at a cost of about $6,500 not including my labor.
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Old 25-11-2019, 06:02   #4
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Re: Playing with some Numbers - Cost of Making Water

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Originally Posted by belizesailor View Post
On a good solar day I can run my Spectra Catalina 300 off nothing but solar for a couple of hours and still end the day with a nearly full SOC house bank. Hard cost of generating power and making water = $0.

Amortized cost per liter is also low given the service life of the water maker and the solar panels. I installed my Spectra in 2004 at a cost of about $6,500 not including my labor.
my rain catcher cost about $15 to build,runs day and night,should last at least as long as the boat
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Old 25-11-2019, 06:08   #5
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Re: Playing with some Numbers - Cost of Making Water

Good option to have too, but for the past few years we've been cruising the San Blas islands in dry season with minimal rain...sure is nice to have a water maker!
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Old 25-11-2019, 09:35   #6
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Re: Playing with some Numbers - Cost of Making Water

Very easy to make ones own water maker at around $1400 dollars, giving a good supply of water , using a CAT high pressure pump and a 1.5kw motor and all the other stuff needed , YOUTUBE is your friend and Google , connect to an inverter , good battery bank and solar and wind and off you go,
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Old 25-11-2019, 10:01   #7
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Re: Playing with some Numbers - Cost of Making Water

What about the "Hassle Factor"?
Would you rather be spending your time exploring a new place or looking for water? And is the water you found safe for you to drink? etc. It seems to me if you are a full-time cruiser and your boat is big enough and if you have or can get the power, then having a water maker makes sense on so many levels. But if you like going to marinas and buying questionable water and you have the time to "explore" for places to get water and you like toting gallons and gallons of water in your dinghy, then by all means, justify not having an endless supply of pure water. As always the choice is yours, Captain.
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Old 25-11-2019, 11:39   #8
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Re: Playing with some Numbers - Cost of Making Water

I have always had a philosophical problem with converting hydrocarbons (Diesel Fuel) into water through the straining process of generators and watermakers.
I know, lots of people do it. They can afford the cost of the units and the maintenance costs and time, paying for some convenience in the short term by not having to look for water during a short time when in a water scarce area.
Carrying around all that extra equipment 100% of the time on the boat, plus the extra fuel, plumbing, maintenance supplies, battery power, etc., just doesn't make sense to me.
I would rather carry that amount of weight in extra water when needed.
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Old 25-11-2019, 11:49   #9
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Re: Playing with some Numbers - Cost of Making Water

Quote:
Originally Posted by Paul Howard View Post
I have always had a philosophical problem with converting hydrocarbons (Diesel Fuel) into water through the straining process of generators and watermakers.
I know, lots of people do it. They can afford the cost of the units and the maintenance costs and time, paying for some convenience in the short term by not having to look for water during a short time when in a water scarce area.
Carrying around all that extra equipment 100% of the time on the boat, plus the extra fuel, plumbing, maintenance supplies, battery power, etc., just doesn't make sense to me.
I would rather carry that amount of weight in extra water when needed.
Your call of course, but jerry jugging questionable water in remote locations sure does suck.
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Old 25-11-2019, 11:53   #10
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Re: Playing with some Numbers - Cost of Making Water

It never makes $$$$$ sense. You either want it or you don’t. It’s about enjoyment not just $$$$$ or why have a boat to start with?
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Old 25-11-2019, 11:57   #11
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Re: Playing with some Numbers - Cost of Making Water

My watermaker is the product of an idle mind. My boat carries 1000 litres in 3 tanks and it is only through my own forgetfulness that we ever run out. That said, we live at home on rain tanks (no municipal supply) as does our sailing club where we fill our boat tanks. So the desire to keep our boat water “un-chemicalised” and having a whole lot of used watermaker components at my disposal I decided to build one.

Now that we have it, it only runs when we have “excess” electricity like when the solars are pumping juice and getting regulated down or when we’re motoring anyway due to a need to get somewhere with no wind.

So other than the nominal cost of building/maintenance of the machine, I consider the cost of “making” water neutral. And if the machine is properly cared for, maintenance costs are really quite minimal.

When sailing in areas of limited rainfall, it is comforting to know that we can still shower regularly and not be under threat of running out of water.
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Old 25-11-2019, 12:28   #12
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Re: Playing with some Numbers - Cost of Making Water

Quote:
Originally Posted by Paul Howard View Post
I have always had a philosophical problem with converting hydrocarbons (Diesel Fuel) into water through the straining process of generators and watermakers.
I know, lots of people do it. They can afford the cost of the units and the maintenance costs and time, paying for some convenience in the short term by not having to look for water during a short time when in a water scarce area.
Carrying around all that extra equipment 100% of the time on the boat, plus the extra fuel, plumbing, maintenance supplies, battery power, etc., just doesn't make sense to me.
I would rather carry that amount of weight in extra water when needed.
Reasonable point , there are 12 v and 24v water makers out there and with good renewable energy input on the boat , one should never run out of water at least to survive
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Old 25-11-2019, 15:40   #13
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Re: Playing with some Numbers - Cost of Making Water

Quote:
Originally Posted by Paul Howard View Post
I have always had a philosophical problem with converting hydrocarbons (Diesel Fuel) into water through the straining process of generators and watermakers.
I know, lots of people do it. They can afford the cost of the units and the maintenance costs and time, paying for some convenience in the short term by not having to look for water during a short time when in a water scarce area.
Carrying around all that extra equipment 100% of the time on the boat, plus the extra fuel, plumbing, maintenance supplies, battery power, etc., just doesn't make sense to me.
I would rather carry that amount of weight in extra water when needed.
our 40' cat was built with 2 x 250L fuel + 2 x 250L water tanks.
one water tank has been converted to fuel so we now carry 750L fuel + 250L water PLUS a 6KvA diesel generator & echotec water maker.
this set up produces 80L FW per hour, for a consumption of abt 0.5L diesel.
IOW, we have swapped 250L FW for the ability to make 40,000L
you cannot carry that much FW on any boat i can afford...
cheers,
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Old 26-11-2019, 04:53   #14
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Re: Playing with some Numbers - Cost of Making Water

Quote:
Originally Posted by Paul Howard View Post
I have always had a philosophical problem with converting hydrocarbons (Diesel Fuel) into water through the straining process of generators and watermakers.
I know, lots of people do it. They can afford the cost of the units and the maintenance costs and time, paying for some convenience in the short term by not having to look for water during a short time when in a water scarce area.
Carrying around all that extra equipment 100% of the time on the boat, plus the extra fuel, plumbing, maintenance supplies, battery power, etc., just doesn't make sense to me.
I would rather carry that amount of weight in extra water when needed.
I assume you row to collect your water.
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Old 26-11-2019, 08:00   #15
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Re: Playing with some Numbers - Cost of Making Water

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Originally Posted by tarian View Post
Very easy to make ones own water maker at around $1400 dollars, giving a good supply of water , using a CAT high pressure pump and a 1.5kw motor and all the other stuff needed , YOUTUBE is your friend and Google , connect to an inverter , good battery bank and solar and wind and off you go,

Yes you can, but the ~$300 CAT pumps are not stainless steel like marine water makers and won't last. The cost difference in the pump alone is significant... like $800 more. When I compiled a BOM to build my own RO system using marine grade material, the cost was about $2,500 and that didn't include tidbits like hose clamps and mounting hardware, etc, which adds up. I decided 1) it was not worth the hassle of sourcing all the stuff considering cruise RO sold complete kits with tech support for about $500-1k more and 2) I wanted a lower draw motor to run off my solar. So I ultimately bought a Spectra 160. works great and I never have to listen to my engine... wish I could say the same about all the other boats in the anchorage!
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