What size water tank with water maker?

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Except for water with oil on the surface (and this is only a problem if you have your intake near the surface) the statement that watermakers do not work well in coastal waters or the ICW is not necessarily true. Discussions with engineers from Kayadyn / Spectra indicated that the only effect "dirty" water has on your watermaker is that the pre-filters get dirtier. If you're changing them every couple of months or so there should be no problem using your RO watermaker in coastal water. One thing to remember about watermaker capatity is that an 80 GPD unit produces just a little over 3 gallons per hour. If you use 10 to 15 gallons a day this means that you would need to run the watermaker 3 to 5 hours a day to meet your needs. There are large capacity machines that would easily satisfy that kind of water requirements but you are talking 5 figures in cost and have a pretty large footprint for a boat the size of yours.

RJ,

Very useful stuff -Thanks!
 
I agree totally. The point I was trying to make is that depending on the water quality you need to change the filters (we had a 2 different micron sizes in series) more frequently, to the point where it becomes a pointless exercise.
How many filters are you prepared to carry so that you can change them every couple of days?? The waster in many areas is so full of sediment and organic material that the filters plug real fast. As previous, we found it pointless to run the RO in the ICW, and have you been in the Chesapeake lately???

My boating experience in the Chesapeake or ICW has been limited to a couple of tourist "cruises". Most of my watermaker use was in the Sea of Cortes and the mainland coast of Mexico and Central America. Mostly clean water there. My reaction was based on a seminar I attended about 10 years ago at Loretto Fest in Baja that was conducted by a former engineer from Katadyn. I asked about using a watermaker in a marina or anchorage given that some areas, at that time, had no rules about direct discharge of waste. His answer was surprising in that he said the RO was so efficient that he did it all the time on his boat. I do agree on filters but I rarely went through more and 3 or 4 an entire winter cruising season I can see where a lot of suspended debris can create issues. Freedom carries 400 gallons of water so I never needed to push the issue of making water in an anchorage and had a UV system to purify tap water at marinas.
 
If you're a coastal cruiser just enough to get from A-B
If you're an island cruiser (bahamas etc.) more is better.
Have had water maker membranes fail (what doesn't).
Also been places in Bahamas where water was not available due to local infrastructure failure or out of range.
What is your water usage? I like to take hot showers every day wash boat do laundry wash dishes etc etc.
There is no right answer.
I would rather have more water than fuel (have 650nm range) because I anchor and shower etc. a lot more than I burn fuel.
You mentioned long range, I would be more concerned with being self sufficient as fuel is easy to get with your range.
Just my HO
 
I'd leave as is. You'll be suprised how mush water you use gunkholing etc. The last thing you want to do is go looking for water every few days 40 galls of water goes nowhere. Having said that I sailed across the atlantic on less than that. Finding clean harbours etc to run watermakers is difficult in some areas. I carry 700 galls of water and it lasts 3-4 weeks with 4 on board in the Caribbean gunkholing etc. We carry up to 1600gals of fuel but normally run with no more than 800 galls. For us its always the water not the fuel. We rarely exceed 100miles between the islands. Our longest run will be from Puerto Rico to Turks and Caicos in the next 12 months, where we'll probably burn some 400 galls dpending on weather etc.. Leave as is and if you want to do a long run put a fuel bladder on the bow!! Save the money and buy a case of good wine.
 
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