Playing with some Numbers - Cost of Making Water

[Tomaz473]

Originally Posted by billdomb

Have always wondered just how much power is needed to feed the RO membranes. COULD it be achieved by a long hand-pump lever?

Every time you walk by, give it a few swings...??

Manual water-makers exist.
Here is on example.


But: Watermakers do not like to be operated a few swings at a time.
First few minutes does not produce good water. You would need to work it hard for longer periods to get drinkable water.
Recently a watermaker broke on a racing yacht (I think it was on a volvo ocean race), so they had to use a backup, manual watermaker.
Two guys were pumping it (one pumping, one resting, taking turns).
They said it was very hard and they hardly made enough for drinking and warming up dry meals.
And these are strong guys in their peak performance - professional athletes.
So, it is possible, but this is surviving situation and you would not hand pump it to take a shower.

I have energy recovery model from Spectra - it uses 240W to produce 50l/h.
I easily run it from solar. I run it for few hours at a time every couple of days.
If there is no sun I run it next day (or shorter time).

[Northbound44]

Originally Posted by Tomaz473

Manual water-makers exist.

Here is on example.





But: Watermakers do not like to be operated a few swings at a time.

First few minutes does not produce good water. You would need to work it hard for longer periods to get drinkable water.

Recently a watermaker broke on a racing yacht (I think it was on a volvo ocean race), so they had to use a backup, manual watermaker.

Two guys were pumping it (one pumping, one resting, taking turns).

They said it was very hard and they hardly made enough for drinking and warming up dry meals.

And these are strong guys in their peak performance - professional athletes.

So, it is possible, but this is surviving situation and you would not hand pump it to take a shower.



I have energy recovery model from Spectra - it uses 240W to produce 50l/h.

I easily run it from solar. I run it for few hours at a time every couple of days.

If there is no sun I run it next day (or shorter time).

Just for fun, I did some conversion:

A Katadyn power Survivor need 4 amps @ 12 volts to produce 1.5 gal/ hr.

4 amps x 12 volts= 48 watts = 41 216 calories/ hour

Peanut butter contains 100 calories/ table spoon. (275 spoon/gal)

One small Pizza Margherita From Pizza Hutt contains 630 calories (43 pizzas/ gallon)

[chrisr]

Originally Posted by Northbound44

Just for fun, I did some conversion:

A Katadyn power Survivor need 4 amps @ 12 volts to produce 1.5 gal/ hr.

4 amps x 12 volts= 48 watts = 41 216 calories/ hour

Peanut butter contains 100 calories/ table spoon. (275 spoon/gal)

One small Pizza Margherita From Pizza Hutt contains 630 calories (43 pizzas/ gallon)

it would also be amusing to work out at what temp / humidity level you would sweat out more water than you make...

cheers,

[nfbr]

This was more about - If I want to live like on land, and waste water for showers etc, how much will it cost me.
Aust water restrictions were at ~140L/Day/Person as a modelling number.
So how cheap could I do that, if living on board all year.

[Pizzazz]

Originally Posted by nfbr

This was more about - If I want to live like on land, and waste water for showers etc, how much will it cost me.
Aust water restrictions were at ~140L/Day/Person as a modelling number.
So how cheap could I do that, if living on board all year.

You need to invest about $3,000 upfront plus the cost of about 70 gallons of fuel per year, whatever that costs in Aust.

[nfbr]

Looking at Energy Cost - At a ridiculous 1000L/Day for a family of 5,
Cheapest looks to be $160/yr (Echotech ER on oversize Solar amortized over design life)
Most expensive looks to be $11,989 yr CruiseRO (on oversize generator) @ $1.59/kw/hr
If you had a larger generator more lightly loaded it would be more $

[nfbr]

Updating the spreadsheet with more info comes some interesting conclusions

Using some flawed assumptions (yes, attack away)

• Watermaker consumables ignored
• Watermaker life is Calendar Age not Use dependent and assumed 100% loss after 7 years of every day use.
• Install and Repair labour / parts not included
• 2 Power sources. 50% loaded Diesel Generator vs Solar w/ Minimal battery

For 1000L
The most expensive option is $79
The cheapest is $3.80

Solar is generally 2x-4x less per KL

Average ranges from $8 - $40

Budget $1000-$3000 / yr for fresh water, depending on what combination you run and your use pattern.

You can modify variables to suit your use & situation

[Paul L]

Originally Posted by nfbr

Updating the spreadsheet with more info comes some interesting conclusions

Using some flawed assumptions (yes, attack away)

• Watermaker consumables ignored
• Watermaker life is Calendar Age not Use dependent and assumed 100% loss after 7 years of every day use.
• Install and Repair labour / parts not included
• 2 Power sources. 50% loaded Diesel Generator vs Solar w/ Minimal battery

For 1000L
The most expensive option is $79
The cheapest is $3.80

Solar is generally 2x-4x less per KL

Average ranges from $8 - $40

Budget $1000-$3000 / yr for fresh water, depending on what combination you run and your use pattern.

You can modify variables to suit your use & situation

Nice info. I think your depteciation is a bit on the high side. It is pretty easy to sell a used watermaker, that has been taken care of, after 7 years for 1/3 of new.

[slug]

Originally Posted by Simi 60

How is it simpler?
You have a machine that makes fresh water powered by a machine that makes electricity.

I have tanks with no moving parts.

If you can get by without a water maker do it

Water makers and the whole associated mess ....takes up space , is expensive and high maintenance

Adding an extra water bladder tank ,then behaving like a seaman, is a viable solution for 90 percent of boats

[Paul L]

Originally Posted by slug

If you can get by without a water maker do it

Water makers and the whole associated mess ....takes up space , is expensive and high maintenance

Adding an extra water bladder tank ,then behaving like a seaman, is a viable solution for 90 percent of boats

Sure is when you are in places that you can get potable dock water along side. It gets a little less attractive when the local water is suspect or you have to jerry jug it in the dinghy or its not available at all. Personally, I wouldn't long distance cruise without a watermaker. Just makes life so much easier.