The Pacific - is a watermaker just a nice to have?

[moomba]

there was a nice thread on these forums about a gentelman who made their water maker for around 1000 pounds , as as usually if you make it , you better understand how to fix it.
I do despair watching people load their boats with 200 bottles of plastic water , were does this go , and the old argument of well
Im only a small part of the big picture can be multiplied many times, like the ARC rally that lands across the pond and dumps 200 boat loads of plastic water bottles for the locals to deal with, in which most of it is burned, not the best for their lungs, and it is even worse in the pafific

 

[jdc]

When calculating the cost of water produced by a watermaker, are people generally powering these from solar or by generator? The latter surely being much more expensive.

One can think of diesel as a sort of concentrated water. lets do some back of fag-packet sums:

Watermaker (mine) draws 9A at 13.5V = 121 Watts. It produces 23 litres per hour, so 1 litre of water requires 0.121 / 23 = 0.0053 kWhrs.

A generator uses almost exactly 0.3 litres of diesel per kWhr. Thus 1 litre of diesel makes 1 / (0.0053 * 0.3) = 629 litres of water.

Diesel costs around 1.30 £/litre, so water from a watermaker costs around 1.30 / 629 = 0.2 pence pr litre. I don't think this is significant! The cost of spares for the watermaker is more, or so I suspect.

As for hassle, I find it overall much less hassle having a watermaker. Against a watermaker is the maintenance (and cost), but in its favour is much less daily fetching of water, often from islands where there is really very little to spare and this of dubious quality. We've also given water away to other yachts when anchored in remote places, thus saving our fellow yachtsmen and women from having to make special trips to unpleasant towns just to top up with water.

But need a water maker? No. Nice to have? Absolutely, provided money's not tight and you are reasonably handy.

 

[AndrewB]

... Thus 1 litre of diesel makes 1 / (0.0053 * 0.3) = 629 litres of water.

629 litres of water from 1 of diesel? I find that hard to credit, is this actual or theoretical? Sailaboutvic's figure of 80/90 litres from approximately 1 litre of fuel is much closer to what others have told me.

Of course, you need a gen as well as a watermaker. That's yet another piece of equipment to carry and maintain - and hope doesn't let you down.

 

[Sybarite]

Some ocean wanderers consider fresh water laundered clothes a luxury. This too becomes a possibility with a watermaker.

 

[sailaboutvic]

there was a nice thread on these forums about a gentelman who made their water maker for around 1000 pounds , as as usually if you make it , you better understand how to fix it.
I do despair watching people load their boats with 200 bottles of plastic water , were does this go , and the old argument of well
Im only a small part of the big picture can be multiplied many times, like the ARC rally that lands across the pond and dumps 200 boat loads of plastic water bottles for the locals to deal with, in which most of it is burned, not the best for their lungs, and it is even worse in the pafific

Yes Chris Jones , Geen and myself and others all build our own , well worth every penny of the £1K it cost me , I only have one membrane I think Geen has three , and he make three times the amount of water I do in the same time .
I have to say a water maker group I contribute to at times , seen to have posting from people who have factory brought water makers which seen to have problems ,
but most seen to be because they don't know how they work or how to fix them when they go wrong , factory unit can and are very complicated , where unit like mine are very simple , not much to go wrong biggest problem we had this year was our pre filters got bugged up and had to be replace , £13 later and five mins and we was making water with a DTS of 105 where the local tap had over 300.
A word of warning , once you have one you won't want to be without a water maker .

 

[noelex]

Of course, you need a gen as well as a watermaker. That's yet another piece of equipment to carry and maintain - and hope doesn't let you down.

The energy recovery watermakers can run happily from solar or wind.

 

[jdc]

629 litres of water from 1 of diesel? I find that hard to credit, is this actual or theoretical? Sailaboutvic's figure of 80/90 litres from approximately 1 litre of fuel is much closer to what others have told me.
...

It's pretty much actual. The current consumption of the watermaker is measured, as is the product flow rate. For the spec see https://www.spectrawatermakers.com/...ds/fact-sheets/ventura-150-specifications.pdf I can confirm that this model does indeed meet the published numbers.

The generator's efficiency is pretty normal also, but is an additive number: ie an extra kW only requires an extra 0.3l per hour. See https://www.whisperpower.com/uk/4/2/287/products/genverter-series-(var.-rpm)/piccolo-45-marine.html for instance: about 1.2 litres fuel is used per hour for 4 kW of power, so 0.3 litres for 1 kWhr. This number applies pretty much to all sorts of engines and sizes, see for instance https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption. Again, I've measured it.

What I am not taking into account is the extra water one has to make to flush the system after each use, which amounts to about 30 mins worth of running. So if you leave it on for 2hrs you only get 1 1/2 hrs worth of water. That makes the multiplier only 629 * 3/4 = 472. But even so, 0.3 p per litre still doesn't break the bank, which was the reason to make the rough calculation.

 

[sailaboutvic]

It's pretty much actual. The current consumption of the watermaker is measured, as is the product flow rate. For the spec see https://www.spectrawatermakers.com/...ds/fact-sheets/ventura-150-specifications.pdf I can confirm that this model does indeed meet the published numbers.

The generator's efficiency is pretty normal also, but is an additive number: ie an extra kW only requires an extra 0.3l per hour. See https://www.whisperpower.com/uk/4/2/287/products/genverter-series-(var.-rpm)/piccolo-45-marine.html for instance: about 1.2 litres fuel is used per hour for 4 kW of power, so 0.3 litres for 1 kWhr. This number applies pretty much to all sorts of engines and sizes, see for instance https://en.wikipedia.org/wiki/Brake-specific_fuel_consumption. Again, I've measured it.

What I am not taking into account is the extra water one has to make to flush the system after each use, which amounts to about 30 mins worth of running. So if you leave it on for 2hrs you only get 1 1/2 hrs worth of water. That makes the multiplier only 629 * 3/4 = 472. But even so, 0.3 p per litre still doesn't break the bank, which was the reason to make the rough calculation.

Jdc , correct me if I am wrong , you useing 100 lts to flash ? I take it's a automatic flash ? We use about 10 lts
Again the difference between a brought one and one you build your self , more control over the water maker .

 

[PhilipH]

629 litres of water from 1 of diesel? I find that hard to credit, is this actual or theoretical? Sailaboutvic's figure of 80/90 litres from approximately 1 litre of fuel is much closer to what others have told me.

Of course, you need a gen as well as a watermaker. That's yet another piece of equipment to carry and maintain - and hope doesn't let you down.

No. We have solar, wind and towed. You do not need a diesel generator- a small petrol generator (say 1kw) is handy and uses very little fuel.

 

[Petronella]

Thanks all

I think first off we'll ensure the third water tank is operational and install a valve to divert all the deck rain water into one of the tanks. If we do decide to install a watermaker it will likely be of the self build variety.

Cheers
John and Gill

 

[jdc]

Jdc , correct me if I am wrong , you useing 100 lts to flash ? I take it's a automatic flash ? We use about 10 lts
Again the difference between a brought one and one you build your self , more control over the water maker .

More like 10 litres. It takes about 3 minutes to flush (I usually skimp a bit and make it 2). In that time it's using about 10x as much as gets through the membrane - a pretty normal bypass ratio - so that's ~ 30 mins worth of water. In an hour I make 23 litres, so in a bit less than 3 mins of flushing I maybe use 10 litres. It's not automatic, I have completely manual controls.

 

[BobnLesley]

So that would be 200 1.5l plastic containers to dispose of in an already over-polluted environment and in particular in the Pacific where recycling is impossible in many places.... The windward side of Pacific islands tell you enough ...

Not actually as bad as you might imagine and in our case in two ways:

When this approach was first suggested to us by a chap in the Canary Islands, we too raised the same question, what the heck were we to do with 100 empty plastic bottles? His reply was first to ask us all to guess just how large a volume of waste plastic we thought they'd generate? I would urge you all to make that same estimate right now, before reading-on.

In the event we didn't buy/take our water in the 1.5 litre bottles, so couldn't confirm his answer until late last year in the San Blas Islands, when a few of us had a beach clean-up afternoon and rather than just burning the sixty-odd bottles of that type which we'd collected, I first followed his policy of how to deal with them offshore: Take a pair of scissors and cut the plastic bottles up into approx 1/2" x 2-3" strips and stow them in your typical supermarket carrier - you've plenty of time to fill when crossing an ocean anyway and even sat at anchor in the San Blas, the 60+ that I used to test his claim only took me a couple of hours or so to chop-up and bag - I hadn't got the full 100, but the experiment was enough to confirm that 100 of them really will 'fit easily into a single bag'.

What we actually bought/took across the Atlantic in January 2013 where 14 8 litre bottle that'd been 'On Special' that week in Lidl - just oversized versions of 5 litre ones you more usually see. I've no idea how small these'd chop-up as almost six years later - to our own amazement too! - we still have six of them aboard and continue to use them as our main jerry-jugs. Of those that're gone I only recall one that actually began to 'leak', One blew away in the wind quite recently and four at least were given away for brewing boat-wine in - they're the perfect size. Not a bad life/usage for lightweight plastic bottles, we've had several 'real' diesel &water jerry-jugs do worse.

 

[temptress]

We have been cruising on several boats for many years. We fitted a water maker in 2013 and it transformed our cruising. Can you do the Pacific without a watermaker? Of course you can. You just have to manage your water carefully. In 2016 we sailed from Panama to French Polynesia in 30 days... We had no rain at all on that trip. We enjoyed having a watermaker, regular showers, clothes washing in fresh water etc. Could we have done the passage without one, yes in fact we always plan our passages assuming the watermaker will break as we leave port.

But they are great to have, they like to be run often and for long periods. We carry a recommended spares kit from the manufacturer and have haf years of good service from our SPECTRA 150....

It is up to you, if i was refitting a new boat for cruising a water maker would be right up near the top of equipment I would like.

So it depends on your budget and style of cruising.

 

[Sea Devil]

Like Dansaskip we crossed without a watermaker. There was not as much rain as we expected, and by the time the two of us reached the Marquesas, out of 450 fresh-water litres capacity we had just 120 left in the tanks (plus an emergency reserve of 50 litres), having used an estimated 400 litres on a 40 day passage. The water available in some Pacific islands is limited and of suspect quality, and if you expect to use it I would recommend fitting a really good quality filter.

Personally though, on this experience and with this capacity, I would not bother with a watermaker if I did it again. However my game-plan does include collecting a fair amount of rain, which is usually not a problem - most often my tanks have been nearly full at the end of an ocean passage.

There is nowhere in the world that you cannot get water. I really would not bother with them. Expensive spares and chemicals and constant maintenance. I had one in the Pacific and would not bother with on next time

 

[Gryphon2]

An interesting aside is whether water makers are good for your health. When we circumnavigated we met more than one boat that had a theory that drinking nothing but desalinated water lacking in the usual minerals was not good. Having said that we bought a bigger watermaker whilst away and enjoyed the ability to not worry about water. The water you buy in places like the Galapagos may also be produced by reverse osmosis...so maybe that is no better.

In 1981 we crossed to the Caribbean in a Vega and carefully kept ourselves to using the then standard of 4 pints per person per day with no problems, except for one salt water curry produced with too much water from one of the 2 taps.