Liveaboard watermaker facts and figures

[geem]

Obviously YMMV, but I pay about £8 for 5.5.cu m of good potable tap water in the UK. Agree that when off the beaten track a watermaker is a good idea, but if mains water is accessible it very quickly looks a poor deal.

When we returned from our previous Atlantic adventure we sold the watermaker. There was little point in having one in the UK.
I put this post up to assist others who may be thinking of installing a watermaker before they head off to places where water is not as convenient, as reliable or as cheap as the UK.
We have a friends who keeps a motorboat in Greece. He installed a large watermaker as he was not happy with the quality of water he was acquiring when he filled up in Greece. I am sure there are reliable location for water in Greece but thats what he did.
People install them for different reasons. This post was not to create an argument between should I or shouldnt I install one? It was to give some facts and figures for those considering it.

 

[crisjones]

Can anyone recommend some good literature or guide that they have used on how to DIY a system? I would be very interested in doing it on my next boat.

A Google search for "Build your own watermaker" will give lots of answers, this one https://sublimesustenance.files.wordpress.com/2012/03/how-to-build-your-own-watermaker.pdf is very comprehensive.

 

[temptress]

Accepted wisdom for watermakers appears to be to fit a big one and run it infrequently.
Does anybody go the other way, and fit a little one that can chug away in the background, running off excess solar capacity? Sounds more civilised and far cheaper, but I'm guessing there's a catch somewhere.

We have a water maker that produces 30 ltrs an hour. We run it off the solar and have never been short of water. It did pack up in the pacific but this was traced to a faulty trip switch (it got wet and fried!). We generally run the water maker for 3 or 4 hours at a time and every 3 or 4 days depending on our consumption. Whenever the engine is on for more than a few hours we put the water-maker on as well. It all fits in with charging cycles - we have a small 1Kw gen set that get used occasionally. Although now we have fitted Air-Con in Singapore I will upgrade the gen-set to cope when finance allows.

 

[geem]

We have a water maker that produces 30 ltrs an hour. We run it off the solar and have never been short of water. It did pack up in the pacific but this was traced to a faulty trip switch (it got wet and fried!). We generally run the water maker for 3 or 4 hours at a time and every 3 or 4 days depending on our consumption. Whenever the engine is on for more than a few hours we put the water-maker on as well. It all fits in with charging cycles - we have a small 1Kw gen set that get used occasionally. Although now we have fitted Air-Con in Singapore I will upgrade the gen-set to cope when finance allows.

How many amps does the watermaker draw? How much solar do you have?

 

[temptress]

How many amps does the watermaker draw? How much solar do you have?

Just say this. Water-maker draws between 8 and 12 amps on 12v. Fridge pulls about 4 amps Solar panels put in between 10 to 14 amps most of the day if sunny much less if cloudy. We have a wind genny as well puts in say 4 amps. (depends on the wind). You need to consider your overall power draw but the 2 biggest consumers are the Fridge and water-Maker. Water-maker is not run every day but every 3 or 4 days or anytime we motor anywhere.

Before a long passage (more than 4 nights at sea) I make sure the water tanks are full. This usually involves engine or genny use.

 

[ean_p]

what make of watermaker do you have please?

 

[geem]

what make of watermaker do you have please?

All the bits to build a watermaker are available. It doesnt need to be a make. Our watermaker has a cat 247 pump. You can use anybody's pressure vessels and membrane as long is is rated for seawater at 1000 psi. The limit on water production with a Cat 247 pump is approximately 280 litres per hour if run at the 1750 maximum rpm

 

[temptress]

what make of watermaker do you have please?

Spectra Ventura - I find keeping the pre-filters clean is key - we have 3 pre filters before the pump.

 

[geem]

Spectra Ventura - I find keeping the pre-filters clean is key - we have 3 pre filters before the pump.

It is normal to have a strainer on the inlet then a 20-50 micron pre-filter followed by a 1-5 micron filter. In very fine silt we run the 1 micron filter but normally use a 5micron. We usually only find the 20/50 micron filter gets particularly dirty.