The Offshore Voyaging Reference Site

Q&A: Should I Get a Watermaker?

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Member Andreas asks:

This is a great article that highlights some of the decisions I need to make in preparation for casting off on an extended trip this summer. My challenge is balancing cost with usability. The sailboat (SY Baluba) will be used for a 3-year circumnavigation now, but afterwards she will go back to being a weekend warrior as well as seeing plenty of usage in holidays, here in Northern Europe.

A new Spectra Ventura costs a solid chunk of change in Europe. When I spent 2-1/2 years sailing from Norway to Australia seven years ago, I managed fine without a watermaker, but it was a bit of a hassle to always be careful with water usage and never take a fresh water shower (while onboard).

Now I’m planning to sail all the way around, with forays both to the Arctic and Antarctic, so I’m wondering if the watermaker will be a necessary expenditure or if it will be something I’ll get used to being without again? Can I justify spending the money for a unit I’ll need and use a lot for the next three years, knowing that there won’t be much (if any) use for it when I get back to Norway?

What are your thoughts?

John answers:

Hi Andreas,

An interesting question. First off, as I stated in the simplicity post you mention, we don’t have a watermaker, but then we have huge tanks (1000 litres) and generally cruise where water is available reasonably easily and for free.

I think that if your voyage will include the typical tradewind routes I would lean toward installing a watermaker. In many tropical places water is both hard to get and expensive, as you probably already know from your last voyage.

There is another benefit with installing a watermaker and that’s that making your own water substantially reduces the chances of getting a water-borne parasite. And I can tell you, having contracted one from water (ironically in Norway), the resulting illness is no fun at all.

Having said all that, there is one other factor that should go into the decision, and that is your own what I call “optimal simplicity level“: If you are the kind of person who can get by with less in the way of comforts and who also hates mechanical complication, you could certainly get away without a watermaker, particularly if you set up some kind of rain catch system—AAC correspondents Christopher and Molly have managed just fine without a watermaker.

And finally, I would ask yourself “Is a watermaker going to be worth its entire price to me for this voyage only?”.  Watermakers don’t do well on boats that are used intermittently and therefore it will, I suspect, have little value to you once you return to weekend sailing.

In summary, I think that, as so often with boats (life too), there is no right answer, only the answer that is right for you in light of your own complexity- and screwup-tolerance.

If you do go without a watermaker, I strongly suggest a good filtration system.

Comments

Does anyone else have any thoughts for Andreas?

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Matt

With useful, expensive but non-essential gear like this, I find it helps to convert the cost to a more familiar basis – usually an effective cost per month, like your shore-based bills.

Say the watermaker costs $6,000. It’ll be used for a three-year cruise, and will eat up some consumables – maybe a $200 membrane, a couple of $250 seal kits and six $50 sets of prefilters – during that time.

In my little example, that’s $194 a month, plus some maintenance time, to have fresh water (not unlimited, but enough to generally not worry about running out) for the duration of the cruise.

Is that worth it? Well, again, it’s up to you. For me, that price is too high; I would prefer to fuss around with rainwater collection, have a relatively inexpensive sterilization setup on the drinking water tap, and keep a compact emergency desalinator in the ditch bag. But if low-fuss fresh water is worth $194 a month to you, then by all means, go for it.

Andreas

I really like your approach. Cost-converting is a good concept, because it tells you exactly how much the piece of kit will cost you. Since I know that I’ll only need the watermaker for 3 years, then it’s easy to break it down, like you did; $194 a month is a high price for water.

The compact emergency desalinators aren’t cheap and in my mind, if I’m spending $1000 for something I’ll hopefully never use, then spending 5 times that amount for something I’ll use daily, is easier to justify. Of course, when it comes to safety equipment we all spend $$$$ on things we’ll hopefully never need.

Marc Dacey

I’ve been mulling this over for some time, as well, particularly as water tanks contribute to our internal ballast of our steel full keeler. We come to the conclusion that “why not both?” is a good answer for us: a modest, simple watermaker to make potable water sufficient for drinking and cooking needs, and rainwater catchment for laundry, washdowns and flushing out the heads. Of course, we are going to be out for five years, minimum, and can be expected to hover in distant lagoons without access to any kind of treated water; this is where a watermaker pays off. I also don’t object, given the sunlight and breeze to make the amps that make the water, to giving away clean water to locals, or trading it to fellow cruisers. So the intention and economics are different, but “watermaker” just sneaks over the line for us of “complication” versus “worth having”. I’ve been influenced, too, by the iffy quality and high price of water in the Caribbean, and therefore clean water is worth the price up front. I would want a modular unit for the purposes of resale or even terrestrial reuse, unless I sold the boat entire when finished cruising. Properly maintained, a good R/O watermaker should last for decades.

Brian

You are amortizing the cost over 3 years but it will still have depreciated value since the lifespan of the unit is more than 3 years. The membranes alone can last longer than that.

So let’s say it costs $6k and all in with installation and filters etc it costs $200/month over 3 years. At the end of year 3 you still have a watermaker. Let’s say it’s depreciated to 60% of purchase price (I’m guessing). Your $6k watermaker may now be worth $3600.

So your amortized loss to depreciation over 3 years is $2400. That means while you are spending $200/month your actual true cost is closer to $100/month.

Okay but now remember that if you don’t have a watermaker you will still need to get water. And transport it. Maybe use up gas to drive in early to get it. Your time is worth something. And so on.

Now I’m not saying everyone needs a watermaker. But your math is grossly oversimplified and not representative of reality.

Bill Attwood

We have a Katadyn Power Survivor 40E. Costs much less than a Spectra, is bomb-proof, is an “all-in-one” unit (plus a pre-filter) and produces about 5 liters an hour at a cost of 5.5 amps. Makes the very sensible cost/benefit analysis which Matt gives much more attractive. We haven´t plumbed it in to the water tank, but use it for our daily requirements when under way, filling a plastic container in one of the galley sinks.
Yours aye,
Bill

Andreas

I might be going at it the wrong way, because I’ve always been thinking that getting a hight output watermaker like the Spectra Ventura or (the now discontinued) Katadyn 160E, is better, because then I could run it for a short period per day, but get a lot of water when it did run.
With your solution you always have drinking water and can use the tank water for all other things.
An added bonus by doing it your way is that it is potentially easier to sell the watermaker, or move over into another boat after my 3-year trip is over.
Definitely food for thought.

Brian

A smaller one may make sense if let’s say it could run off just renewable and not need a generator. If you have a hydro gen or PV that can run a smaller one as-needed you are basically getting “free” water. You may not have enough juice to run a bigger one off renewables. OTOH if you are running a gas gen for electricity then a bigger one may make more sense.

Plus a smaller one is cheaper and well.. Smaller.

Scott Fraser

John has summed it up pretty well, but let me add two more points.
Another thing to think about is the power source. If you have a generator you can install a bigger (20 +|- gal/hr) unit that runs on AC power. Run the genset an hour a day and you have more water than you need and charged batteries to boot. Without a genset you may need a smaller output 12v system that then requires the main engine to be running or a high output wind or solar system.

Another element in the equation is that seawater temperature has a big impact on output. In the tropics (80 deg F) our 20 yr old system will sometimes produce over 20 gal/hr. In Maine (55 deg?) we get about 12 gal/hr. I imagine in high latitudes the output would be less than 10.

You know the saying: “Everything on a boat involves trade-offs”.

Andreas

It’s a very good point to keep in mind the power source. I won’t have a generator, so I’ll be using wind and sun to keep my batteries topped up. Running a watermaker can potentially cripple that plan, but I’m looking at how to best solve my energy needs.

Marc Dacey

It’s a question between all your other draws versus your battery capacity and charging capacity and the amount of motorsailing you do. I plan to make water only when I’m motoring by the application of a big alternator; I will have more than enough to keep up with the drawdownm although “between 10 and 2 PM between 20 N and 20 S” should work as well without the engine contribution. I find (to date, because I’m still researching) that a modest draw, modest output watermaker makes more sense for us if we consider separate tanks as I described above: it’s neither hard nor expensive in terms of dollars nor energy to keep a 50 gallon tank of “just drinking water” filled if you have two or three other, similar tanks with rainwater for everything else.

Bob T

Hi all, as John knows I’m pretty passionate about safe, pure, abundant FW aboard and it will show through as I write. I too got a parasite back in the seventies. Mine came from an ice chunk placed in my warm beer in Guatemala. Never again, those bugs stayed around for years. Matt’s cost analysis is good but it lacks two line items, the cost of “suspect” dock water and the cost associated with assuring it is safe. Even catching rain water has a cost associated with it. I place safety above all costs. In most countries with ground water (especially islands) have very hard water, usually >500 ppm dissolved solids and a healthy (or not) dose of disinfectant usually chlorine. It usually isn’t free. Where I cruise its $.30-.50/us gallon and then may not be safe. We make 100% of our FW needs and have since the parasites invaded. We also candle the water (uv filter) allowing us to make water virtually anywhere if you don’t mind cleaning filters. We have a power boat now with all the bells and whistles and use copious amounts of FW FW flushing heads, anchor washdown, 60psi household fixtures) but we have it. The cost is minimal above the capital cost of purchase and installation. If you have a generator a WM is the ideal load, steady and constant. The generator only runs a few hours a day and the WM is on line producing a load and all the FW we could possibly use. We have two units, together producing >80gph. We use washable pre filters and have a convenient set up to rinse the units often. Prior to two years ago we were cruising sailors with a single 20gph unit, again matched our 2-3 hr gen run times. While sailing long legs or anchored the generator ran twice daily for 1.5 hrs each cycle for battery charging and the 60 gal replenishment of the FW. That’s sufficient to rinse down underway and still take showers etc anytime you feel the urge. I’ll assume the question comes from a DC only boat. If so a DC unit is your best option. They are more expensive to purchase indeed but invaluable in my opinion vs dependency on catching rain or trusting suspect municipal water supplies. You are correct, they don’t lie idle well and have little resale value so it’s a three year investment. Regardless of your power source visit CruiseRO.com. Rich, the owner is a cruiser like us with a unit to match any budget. I have used them exclusively for years now. You won’t regret contacting them.

Matt

If water safety (parasites, coliform, etc.) is a concern, then I would highly recommend installing a Sterilight S2Q-P-12VDC ultraviolet sterilizer in the potable water line from the tanks to the taps. It draws just 17 watts, costs under $400, requires about 4 minutes and $40 per year of maintenance, and kills *everything*.
I have its larger sibling, the S8Q-PA, in my water system at home. Every water sample we’ve taken to the health department has come back straight zeroes for all biologicals.

Andreas

We filled our tanks in Panama, before sailing to Galapagos and ended up with water that tasted fine at the dock, but for some reason ended up tasting terrible when we got it in the tanks. Does the Sterilight do anything if you get a batch of bad tasting water?

Matt

UV sterilizers just make the water biologically safe, assuming it’s already pretty much free of sediment, heavy metals and other inorganics.

Our home system, which is very similar to what I’d install on a boat, is:
Fresh water source (well/lake on land, water tanks aboard ship).
Pump.
Filter to 5 microns (removes sediment).
Carbon filter (removes taste/odour).
UV sterilizer (kills pathogens).
Potable water taps.

Even with a watermaker, I’d want this setup. The watermaker outputs safe drinking water, but it doesn’t do anything about pathogens or leachates that might crop up in the storage tanks.

Andreas

Only towards the end of my trip to Australia, did I install a filter, so I was very lucky and never experienced any parasites. I’m more mindful of it now and it’s one of the two reasons why I’m interested in a watermaker: a steady and safe source of water.
I’ll have a good look at Rich’s site: http://cruiserowaterandpower.com and weight his options to a more known brand like Katadyn og Spectra. I’ll definitely need a DC system, because I’d like to make do without a generator.

Marc Dacey

I’ve spoken with Rich Boren, and have been impressed with his designs and his logic. His is the sort of DC unit I would consider.

Gene Gruender

We have a powersurvivor 35. Haven’t used it in a few years, but when we were out full time we found it to be invaluable. At about 35 gallons a day, we found it was more than we’d need with one child aboard. When we had guests we had to run it most of the time (non sailors/non cruisers use a lot more water!) but it still provided enough that we could go indefinately without worrying about water. Which brings me to our biggest benefit.

Frequently we’d find a remote place we really liked. We’d have other cruisers we met traveling with us. Usually they’d have no water maker. They were constantly planning around where they might find water next and would have to leave long before they wanted to go in search of expensive, questionable quality water. We’d stay as long as it suited us. It really freed us up to cruise as we’d like.

I have a short list of things I would not leave without, probably in this order.

1. Autopilot
1. Bimini (yes, both #1)
2. Refrigeration
3. Water Maker

There are a lot of other things I’d want, but those are deal breakers.

In 2 years of constant use it never broke down, and still worked each time it laid dormant for a year.

Andreas

I’ve bought a WindPilot Pacific, so hopefully that will be #1 on my list together with a Bimini.
How long did you run your watermaker per day and what was your power source?

Gene Gruender

We were power hogs, the watermaker was just another item along with 12 volt refrigeration, many lights, x boxes and those toys for the kids. We also made sure we had the brightest anchor light around, and this was before LEDs. It probably was 25 amp hours, but we slept better. So, we probably generated more power than most needed.

We had 4 75 watt solar panels, a small wind generator and a 150 amp alternator. We probably ran the water maker on the average 8 hours or less a day. 10 gallons a day would do us fine, unless we had visitors. Visitors are not so frugal with water, so it usually ran most of the time during a week or so of each visit. We tried to run it when we were either putting power in from solar or the alternator, it’s much more efficient if you don’t have to convert it twice.

There are a lot of watrrmakers around, some trickle like ours, some are like a fire hose. I haven’t heard of any that were just crap, so I think you just have to figure out what suits your situation best.

If you go with 12 volt, you can improve things by spending some time fine tuning your charging systems and storage methods. There has been a lot of information about that subject on this site, and as many opinions on that as there are on watermakers – probably more – so, study it all and give it your best shot.

Gene Gruender

I should mention that when we bought ours they were in a slump and offered the 35 at about $1600, threw in an 06 handheld for free. I see that a 40 is now nearly $4k where ever you buy it and an 80 is only $600 to $1000 more. I really don’t understand how the price got jacked up so much, but if we were starting over today I’d still get a 12 volt unit, but probably grit my teeth pretty bad, cuss a lot and get an 80.