Seeking fresh water from salt water help

[Coddiwomple]

We are a family of three on a 40 hunter sailboat heading from Ontario Canada to the bahamas and further end of summer and we are seeking a water maker. I was asked what our daily freshwater requirements are and we have no idea. does anyone have any advice on how to figure this out or if you have lived abroad and have an idea of what we might require on a daily basis.
Thank you
j

 

[Coddiwomple]

We are seeking this as we are looking for a water maker right now and our boat show is coming up in January.

 

[whatfiero]

Standard is 1 US gallon per person per day

 

[Don Crowther]

My Doc says I should drink 2-3 litres a day. But if you put it in your scotch you might need more.

 

[whatfiero]

Water maker's are kinda a over priced energy Hogg most coastal cruisers don't have one or use one and even most off shore sailer don't have one it's a real nice item but water management and storage tanks usually surpass a standard watermaker's production

 

[Coddiwomple]

My Doc says I should drink 2-3 litres a day. But if you put it in your scotch you might need more.

Haha, Fantastic answer. Scotch is a no go for me, but i'll insert the word vodka.

 

[whatfiero]

Vodka might be more efficient to make on board than water

 

[Gunni]

I would want at minimum 10 gallons of water per day per person, drinking, bathing, washing. After that your decision comes down to how you will power your watermaker because they have a rated hourly output in gallons. DC power - you will need to factor the hourly amperage load into your power budget. Engine PTO - you will need to figure in your diesel consumption to drive the pressure pump. Have a generator, AC power is an option.

even most off shore sailer don't have one it's a real nice item but water management and storage tanks usually surpass a standard watermaker's production

Watermakers are an essential piece of kit for places like the Bahamas.

Also make sure you can dump your holding tanks - pumpouts are rare in the Bahamas.

 

[Johnb]

The amount consumed for drinking, tea and coffee making, tooth brushing and utensil cleaning etc. is really not very much, we estimate 3 US quarts per person per day.

After that, the amount of water used for comfort can be any amount but we figure by really taking care we can wash ourselves and get a shower on another 3 gallons per person per day. If you have short hair you can get wet, soap up, rinse with sea water and then rinse with fresh water for a total consumption of 1.5 gallon max, it all depends on how much trouble you are willing to take.

In the end the point Gunni makes is absolutely true, the limitation may well be how much electrical power you can/want to feed the unit. The Spectra 40E specs say it will give you 1.5 gal per hour with a consumption of 4 ampere- hours/hour at 12 V DC. So to make 15 gallons you would have to feed it 40 ampere hours. Take it from there.....

 

[All U Get]

Most of the Chesapeake and the ICW has silty water probably not good to make water with. Once you make water you'll need to make it several times a week to keep the membrane fresh. So you won't get much use of it unless you're off shore a lot. Bahamas are much cleaner.

For the two of us we can carry enough for three months and buy drinking water when needed. Compared to the price of a system, running it, and maintaining it, we figured a 12-15 year payback.

All U Get

 

[capta]

I built our watermaker and probably saved 3k on it over buying a commercial unit.
The first and most important part one needs is the high pressure pump. I searched online for several months until I found one that had just a few hours on it as it was a test unit for a new line of watermakers from a well known watermaker company, at about half price. That was over a grand saved right there. After that it was easy matching parts to suit the pump. As we have a generator, I went with a 110 vac pump. It has been running flawlessly for 5 years now.
My suggestion is to buy the biggest unit you can afford, money and space wise. I couldn't see running our generator for hours and hours, when we can make 40 gallons in one, as with 110 volt refrigeration and cooking, the gene must run anyway. However, there are periods, like heavy rains, poor water quality harbors or anchorages, or just days when one doesn't feel like making water, so it's nice to make a bunch when one can.
If you are heading for the tropics, I'd recommend at least a gallon per day per person, but there are plenty of days when we drink more. Add to that coffee, tea, soups and washing some items best not washed in sea water, more like 3 a day is not out of hand. And then there's the shear decadence of taking a fresh water shower when one wants, even at sea, that makes our watermaker a true blessing.
After nearly 50 years of water rationing, our watermaker has added a level of comfort and civilized life to cruising, undreamed of when I sailed out the Golden Gate, bound for adventures in paradise, all those years ago.

 

[Coddiwomple]

So many awesome answers. Thank you all for your input. have some deciding to do but each comment even the scotch is appreciated. Merry Christmas.

 

[Coddiwomple]

alright I am not done yet. This was sent to me as an option...
http://www.villagemarine.com/images/7829_Little_Wonder_D.pdf

 

[Gunni]

I'm guessing that your boat, like mine has precious little extra room to install a watermaker so these modular units are really attractive and allow you to install a bigger system by distributing the parts. Village Marine is not the only one to make a modular unit. There appears to be a huge variation in satisfaction with watermakers so take your time, review, ask lots of questions and shop carefully.

 

[PaulK]

Sounds like a lot of people cruise a long way without watermakers and the problems associated with them. (energy consumption, bacteria, breakdowns,...) How did you come to the decision that you need one? Drinking-quality water is generally available dockside at most marinas - even in Bermuda, where catchbasins are the rule. If it's not free, you would still probably have to buy enough to fill (and sink) your boat before the cost built up to the price of most watermakers. If you're unsure how clean it is... boil it. From what we're hearing about watermaker energy consumption, even that would be more energy-efficient.

 

[capta]

Sounds like a lot of people cruise a long way without watermakers and the problems associated with them. Drinking-quality water is generally available dockside at most marinas .

I have rarely had better quality, safer water from a shore based source than my watermaker can make. More often than not shoreside water was nearly undrinkable, either way over-chlorinated or just foul tasting. If you really want to get your water from shoreside, that entails docking relatively frequently, sometimes in pretty poor conditions such as Christmas Winds and/or strong surges from winds north or south of east, with the inherent risks that involves.
That extra time on one's main engine versus the time on a smaller, more fuel efficient generator hardly seems more energy efficient to me. Most folks down here buy bottled water for drinking if they don't have a watermaker, not the best thing for the environment, either.
I sailed around the world before GPS was even a twinkle in some engineer's eye, but that doesn't mean I won't use my nice 10" display GPS chartplotter. It's the cruisers w/o the watermakers that I don't understand. It's certainly much higher on my list of important and useful equipment than AIS!

 

[JamesG161]

either way over-chlorinated or just foul tasting

Also if you have an Aluminum water tank, no more tanks corrosion from dissolved chlorine.

Since you are in charge of your water "potability", (Reverse Osmosis water is bacteria free at production time) make sure your fresh water system stays clean.

When boat shopping, my first Sea Trial boat had this system installed.
http://www.downwindmarine.com/Katadyn-PowerSurvivor-80E-Watermaker-12V-p-91001016.html
I didn't buy that boat but did some basic research on maintenance and repair. The membrane is basically "filter like" desalination part. I would look for...
1) Ease and cost of changing the membrane
2) Look at the production rate as GPH ( gallons per hour) per AMP consumed.
3) Space to adapt in your current fresh water system.

Tip: Brackish water makes water faster than Caribbean Waters at the same temperature.
Jim...

PS: Triva: Most bottled water is Reverse Osmosis water. Read the label to see NO Chlorine.
PSS: The owner of that boat said "Diesel is cheaper than Water in the Bahamas"

 

[Stu Jackson]

http://www.cruisersforum.com/forums/f2/how-long-do-you-run-your-watermaker-177134.html

 

[Justin_NSA]

I sailed around the world before GPS was even a twinkle in some engineer's eye, but that doesn't mean I won't use my nice 10" display GPS chartplotter. It's the cruisers w/o the watermakers that I don't understand. It's certainly much higher on my list of important and useful equipment than AIS!

How old are you Capta? GPS began with Sputnik !

 

[Terry Cox]

Not to throw fresh water on this thread, Karen Thorndike was the first woman who sailed solo around the world in the late 90s in a 36 foot sloop with a 32 gallon water tank. No water maker, but did have a wind vane steering system. Her position was, when I talked with her, that we are way over washed. Her longest stint between ports was 90 days during this voyage.

An alternative source of fresh water while at sea is collecting rain water, which she did. Washing (body, dishes, clothes) with sea water another cleansing source, which she also did. It is just a matter of preferences and priorities.

Water makers consume a considerable amount of power depending upon usage. So, if your family is accustomed to consuming large amounts of fresh water while at sea, best to outfit the boat with an assortment of electrical generating/storage devices. Just say'n.