Cheapest off the shelf watermaker?

[geem]

That's food for thought, thanks.
I wouldn't have to run on 12v direct- we already have a 3kw inverter for the galley.
We would be running from solar no matter what, but it doesn't really make any difference what the working voltage is. I'd have generally preferred 12v for efficiency, all else being equal, but it sounds like all else is not equal...

There are lots of ways you can use your solar capacity. We have 720w on the domestic bank. We harvest about 2kw per day as we choose to use the spare solar once batteries are charged to make a tank full of hot water. This means hot showers and plenty of water for washing up. Something that the wife with her love of cooking seems to make lots of. The 15 mins a day on the generator to make water (at what would be 200amps at 12v) uses very little fuel and the annual run time on the generator is Less than 100 hrs per year. We have the ice maker running at the moment off solar pulling 100w.
Hope you sort out your watermaker. For us it is a game changer in the Caribbean. We really wouldn't want to be without it.

 

[Neeves]

Have a look at Rainman Water makers. Rainman Watermakers & Saltwater Desalinators. Portable or Installed. - they originally offered a unit based on a Honda motor and now offer a complete family of units. I think they have an option for all desires. They are assembled, they don't make anything - they simply buy off the shelf parts (as you would if you were building your own) - their options may give you ideas of building your own..I used their Honda powered unit when it was first released, dead simple stuff.

They assemble just down the road from us and I have checked out the other units they make. I have not checked but they might have a UK dstributor (they certainly will have one in the US)

I don't know how Rainman fit into the price spread sheet, we already have a Spectra unit. I'd not comment on what is best - I don't know enough - but we would not do without one - de-sal units are liberating. No longer do we eke out water and look for taps - we now each have 2 (hot) showers a day and wash up in hot water (gas instant hot, boiler)

Jonathan

 

[Kelpie]

Have a look at Rainman Water makers. Rainman Watermakers & Saltwater Desalinators. Portable or Installed. - they originally offered a unit based on a Honda motor and now offer a complete family of units. I think they have an option for all desires. They are assembled, they don't make anything - they simply buy off the shelf parts (as you would if you were building your own) - their options may give you ideas of building your own..I used their Honda powered unit when it was first released, dead simple stuff.

They assemble just down the road from us and I have checked out the other units they make. I have not checked but they might have a UK dstributor (they certainly will have one in the US)

I don't know how Rainman fit into the price spread sheet, we already have a Spectra unit. I'd not comment on what is best - I don't know enough - but we would not do without one - de-sal units are liberating. No longer do we eke out water and look for taps - we now each have 2 (hot) showers a day and wash up in hot water (gas instant hot, boiler)

Jonathan

According to their site, the cheapest option (AC) works out at £3400 at current exchange rate. So certainly at the cheaper end of the scale and not a bad price for the output.

Answering my original question, so far the cheapest off the shelf watermaker I've found is the Katadyne 40E, 5.7lph, £3000 inc taxes available from Spanish chandlery. I've heard mixed reviews about it and it would need long run times to keep up with even modest usage.
A kit of parts to build a Karcher-based system is even cheaper, if the guy who does them is still in business- about £2100 inc taxes within the EU. That would produce 55-60lph and output could be doubled by spending another £750 on a second PV/membrane.
Self source and build looks like it would work out cheaper yet, with most people quoting figures of sub £2000 even when using more expensive CAT pumps.

There do seem to be a few options in the £3500 range, and obviously lots more as the price goes up.

I'm leaning, inevitably, towards the DIY route, especially if I can get parts from Amazon- it seems that post offices around here will accept deliveries. That ties me to needing to be in a certain place at a certain time, but at least I don't need to be paying marina fees. I'm not a fan of Amazon but until other retailers match that service I have little choice.

 

[grumpygit]

According to their site, the cheapest option (AC) works out at £3400 at current exchange rate. So certainly at the cheaper end of the scale and not a bad price for the output.

Answering my original question, so far the cheapest off the shelf watermaker I've found is the Katadyne 40E, 5.7lph, £3000 inc taxes available from Spanish chandlery. I've heard mixed reviews about it and it would need long run times to keep up with even modest usage.
A kit of parts to build a Karcher-based system is even cheaper, if the guy who does them is still in business- about £2100 inc taxes within the EU. That would produce 55-60lph and output could be doubled by spending another £750 on a second PV/membrane.
Self source and build looks like it would work out cheaper yet, with most people quoting figures of sub £2000 even when using more expensive CAT pumps.

There do seem to be a few options in the £3500 range, and obviously lots more as the price goes up.

I'm leaning, inevitably, towards the DIY route, especially if I can get parts from Amazon- it seems that post offices around here will accept deliveries. That ties me to needing to be in a certain place at a certain time, but at least I don't need to be paying marina fees. I'm not a fan of Amazon but until other retailers match that service I have little choice.

Plenty info out there, one just needs to do the homework. I haven't watched any but if your wanting to build your own you will probably need to read and watch as many articles as possible.

 

[Yngmar]

Maybe this is useful. It's what I made for myself as decision aid in 2019.

The membrane length is on there as it's the most difficult part to find space for on a boat.

 

[Kelpie]

Maybe this is useful. It's what I made for myself as decision aid in 2019.

The membrane length is on there as it's the most difficult part to find space for on a boat.


View attachment 135889

Great summary, thanks! I can see why you chose the Zen30 based on that.

 

[dgadee]

I built one and am glad I have it. However I reverse engineered a US one so had problems with parts. It basically is similar to a few of them around now - Cruise RO is I think one company.

I started with a honda EU20i but now use a 2kw invertor when engine is running. An hour every three or four days seems to do us. I went US pump and needed a low start up power motor which was an awful hassle to get (no-one gives start up spec) due to face connections. An option I should have considered was a 3 phase motor and invertor. It takes up space - two three foot long tubes - but it is all in the unused junk room cabin (11m boat).

I would have liked more info before I started, but very difficult to get. A sub forum here might be useful.

 

[geem]

I built one and am glad I have it. However I reverse engineered a US one so had problems with parts. It basically is similar to a few of them around now - Cruise RO is I think one company.

I started with a honda EU20i but now use a 2kw invertor when engine is running. An hour every three or four days seems to do us. I went US pump and needed a low start up power motor which was an awful hassle to get (no-one gives start up spec) due to face connections. An option I should have considered was a 3 phase motor and invertor. It takes up space - two three foot long tubes - but it is all in the unused junk room cabin (11m boat).

I would have liked more info before I started, but very difficult to get. A sub forum here might be useful.

Did you consider running a pump directly off the engine via a clutch? Cut out the reliance on the motor and inverter. I know a few that do that

 

[dgadee]

Did you consider running a pump directly off the engine via a clutch? Cut out the reliance on the motor and inverter. I know a few that do that

Not really. I thought that rather than a needle valve (cheap) I would need an expensive valve to deal with changine revs. I now understand that some control revs of the engine to get the desired pressure at the pump. I also thought engineering the pump fitting would be difficult and require more space than I have. I can see it as an option but not one I would do even now. My motor option works well and hasn't given any problems to date.

Of course, there are not many practical descriptions of engine run pumps. There are references to them but I can't remember seeing details or pics.

 

[geem]

Not really. I thought that rather than a needle valve (cheap) I would need an expensive valve to deal with changine revs. I now understand that some control revs of the engine to get the desired pressure at the pump. I also thought engineering the pump fitting would be difficult and require more space than I have. I can see it as an option but not one I would do even now. My motor option works well and hasn't given any problems to date.

Of course, there are not many practical descriptions of engine run pumps. There are references to them but I can't remember seeing details or pics.

It like installing a second alternator. Not really complicated. The Cat pump lends itself to it. Cat do a electromagnetic clutch as well.
Mine runs off a generator and 2hp motor but if I had no gen I would have gone engine driven

 

[dgadee]

As a PS, we prefer to anchor. Crew said, just yesterday:

"It's great not to have to think about where to get water. You just make it."

 

[geem]

As a PS, we prefer to anchor. Crew said, just yesterday:

"It's great not to have to think about where to get water. You just make it."

We are making it as I type. 200 litres/HR?

 

[dgadee]

It like installing a second alternator. Not really complicated. The Cat pump lends itself to it. Cat do a electromagnetic clutch as well.
Mine runs off a generator and 2hp motor but if I had no gen I would have gone engine driven

Yes, but I could find no info on that approach. Perhaps someone could do an overview with a few pics for others?

 

[noelex]

It is tough to run an electrical non energy recovery watermaker from solar on a boat without a generator.

Make sure you do your electrical sums based on your water needs before going down this route.

Unfortunately, there are no energy recovery watermakers in your budget, but at least by realising how much power non energy recovery watermakers need you will avoid buying an expensive paperweight.

 

[dgadee]

Why are there generators on boats in the Med? My big power user is the fridge, nothing else. I run the watermaker when the engine runs - new Yanmar but not huge alternator. 250 watts solar.

Where is all this generator power going? I am thinking my Honda (originally for the watermaker) will be sold for non use.

 

[Clancy Moped]

Why are there generators on boats in the Med? My big power user is the fridge, nothing else. I run the watermaker when the engine runs - new Yanmar but not huge alternator. 250 watts solar.

Where is all this generator power going? I am thinking my Honda (originally for the watermaker) will be sold for non use.

9 out of 12 months on the hook, one needs some home comforts.

 

[noelex]

Winter in the Med is OK without a generator, but you need a well designed and efficient electrical system if you want a comfortable lifestyle.

A good tip is to try a winter in Scotland, you will then think winter in the Med has an abundance of solar power .

 

[geem]

Why are there generators on boats in the Med? My big power user is the fridge, nothing else. I run the watermaker when the engine runs - new Yanmar but not huge alternator. 250 watts solar.

Where is all this generator power going? I am thinking my Honda (originally for the watermaker) will be sold for non use.

We run the generator for 15mins per day. Makes us 50 litres of water. 720w of solar. Solar makes us hot water, ice and runs two fridges and freezer.
Batteries get to float before lunch each day.

 

[Kelpie]

We're anchored in Addaia, Menorca just now. There's a boat nearby running its engine. I mean, why?? With the current cost of fuel a solar panel would pay for itself in weeks, if not days. I can only assume that they've had some sort of system failure.

We are finding that our tanks last us over a month. Showering is the biggest variable. When it rains, we can collect water for that. It's pretty easy to cut back on showering too, especially where there are beach showers to use.

I haven't decided on a system yet. For now we are obviously doing just fine without- our last fill cost us one Euro.
I will need to do the sums to see if energy recovery is necessary. We have 960w solar installed, mostly feeding lithium so it works very efficiently. Another 250w in reserve which can be deployed when we are not on passage, but I've stopped bothering because we simply do not need it. Most days we are at 100% SOC by mid afternoon. We can vary how much we consume by choosing what to cook, and in extremis we can switch from electric to gas. It's the abundance of solar that prompted me to think about a watermaker.

One question- I know that you need to run the watermaker every 3-4 days to keep it happy. But how long a run will it need? We don't have a big battery bank and only really have one day of reserve power. So we would want to make hay while the sun shines, and top up the tanks only when we had plenty of excess power. If we only need to do a ten minute run to keep the watermaker happy, then that's fine, but if it needs a proper blast that could turn out to be a bit of a problem.

 

[geem]

We're anchored in Addaia, Menorca just now. There's a boat nearby running its engine. I mean, why?? With the current cost of fuel a solar panel would pay for itself in weeks, if not days. I can only assume that they've had some sort of system failure.

We are finding that our tanks last us over a month. Showering is the biggest variable. When it rains, we can collect water for that. It's pretty easy to cut back on showering too, especially where there are beach showers to use.

I haven't decided on a system yet. For now we are obviously doing just fine without- our last fill cost us one Euro.
I will need to do the sums to see if energy recovery is necessary. We have 960w solar installed, mostly feeding lithium so it works very efficiently. Another 250w in reserve which can be deployed when we are not on passage, but I've stopped bothering because we simply do not need it. Most days we are at 100% SOC by mid afternoon. We can vary how much we consume by choosing what to cook, and in extremis we can switch from electric to gas. It's the abundance of solar that prompted me to think about a watermaker.

One question- I know that you need to run the watermaker every 3-4 days to keep it happy. But how long a run will it need? We don't have a big battery bank and only really have one day of reserve power. So we would want to make hay while the sun shines, and top up the tanks only when we had plenty of excess power. If we only need to do a ten minute run to keep the watermaker happy, then that's fine, but if it needs a proper blast that could turn out to be a bit of a problem.

We runs ours for 15 mins a day. That enough to keep membranes sweet. I think running little and often is far better for membranes and filters than leaving it a few days