New water maker thoughts?

[Nom de plume]

Having so far failed to find a replacement boat we have pretty much committed to a full (ish) refit of onboard systems for our existing beloved as we are determined to be heading for warmer climes as soon as the restrictions are lifted.

Caribbean is next winter destination and having decided on the new Generator (Beta / Kubota thanks to the other thread) our thoughts turn to a new water maker (None fitted at present so clean sheet). We have about 220 gal water capacity in stainless tanks and most of the time there will only be the two of us onboard so I reckon that worse case we might need a top-up of say 50 gal max in any 24 hour period.

I've started some initial research but before I go much further any input from those with the knowledge (especially from tropical climes) would be appreciated. We are basically a 24v boat but have 12v and 240v ring mains so I guess that should be the starting point? Any thoughts from the wise - the last one that I bought was 1997 so probably a little out of date on the subject!

 

[jdc]

We fitted a water-maker to our 42' (12.8m) boat when going to the tropics, and it was superb. We'd leave port with tanks low on water as we knew we'd be able to make clean and better-tasting water when offshore the we ever could obtain in port! This gives autonomy and lowered health risk, which is especially important when off the beaten track in the tropics.

We fitted a 12V (but 24V versions available) Spectra 'Ventura 150' which is quite a small one but proved perfect for our consumption. It draws 9A at 12V (the 24V model draws only 4.5 as you'd expect) for 24 litres an hour so no need to run engine or generator to power it.

It may seem rather a small output, but I found that the smaller size is actually something of a practical advantage. Some considerations:

1. A water-maker needs flushing of its seawater input with fresh if it's to be left unused for longer than a couple of days.
2. Flushing uses a volume which takes around 30 mins to make, so avoiding it is good, and if you must flush then it's inefficient if you haven't run the water-maker for a few hours at a time.

So, in my opinion, the optimal size is about 3hrs running every 2 days, ie you should choose one which makes a little less in an hour than you use in a day.

In our case we consume around 30 litres a day when not trying to conserve water (our tanks are 500 litres, which, if trying to save water, last 30 days or so and 15 if not, which backs up my 30 litres a day estimate) so the 24 litres a day from the Ventura 150 proved just right. Water-makers, like diesel engines, like to be worked often and hard!

 

[Clancy Moped]

Our's never missed a beat, simple, and they come from where your going.

ECHOTec Watermakers - Manufacturer & Global Supplier

 

[jonic]

Our's never missed a beat, simple, and they come from where your going.

ECHOTec Watermakers - Manufacturer & Global Supplier

Yes we had an ECHOTec too and was always reliable, perhaps because it is so simple?

 

[Clancy Moped]

Yes we had an ECHOTec too and was always reliable, perhaps because it is so simple?

You sold mine to a Dutchman ??I belive they were designed for the Caribbean charter market, which as you can imagine gets quite a lot of abuse..

 

[roaringgirl]

We're currently in the tropics. We have 450W of solar and a good windgen. We have a fridge but no freezer. We have a schenker modular 30 watermaker, that makes 30L an hour for 8A at 12V. We are a family of 4 and it can easily keep up with our consumption without having to burn diesel to generate power.

Before we had the windgen in Madeira and the Canaries, we did sometimes run low on power when using the electric autopilot and making water on long passages. The addition of the windgen and using the hydrovane solved that.

 

[NOHOH]

EchoTec do a main engine driven compressor....so...if there`s no wind ....you put the main engine on.....so you can get somewhere ..and if you switch the electric pump clutch on it will make water and charge your batteries at the same time.......Tank Full?.......its time to do the laundry!....and still have a full water tank at the end.....Simples

 

[pyrojames]

The ECHOTec looks very similar to my home build. Little of no electricery to make it stumble.

 

[roaringgirl]

Presumably you can't run eco-tech without the engine.

 

[dgadee]

The ECHOTec looks very similar to my home build. Little of no electricery to make it stumble.

What motor are you using out of interest?

 

[NOHOH]

Have a look at this.... Belt / Engine Driven Watermakers, High Output (Modular).

If you don`t carry a petrol generator or have a huge battery bank.....then your watermaker neednt be electric powered

 

[Lacey.Sail]

.

 

[geem]

If you are having a new generator is would make sense to utilise it to run a watermaker. We have 200 gallon tank. We run a 220v watermaker that makes 200 litres per hour in the warm waters of the Caribbean. We only need to run it every two or three days. We only make about 100-150 litres at a time so run time is short. My view of watermakers since we have had both 12v types and 220v is that being able to make lots of water quickly is great. If you have to run the watermaker for several hours at a time you have to coordinate that time with being onboard. Once you have a big watermaker you can live like you are at home. Long showers, clean clothes, plenty of water to wash up. Even water to rinse the salt of the decks. You will find a high output 220v watermaker is far cheaper than a high output 12v watermaker and far more reliable.

 

[pyrojames]

What motor are you using out of interest?

PTO from the main engine driving a CAT 277 pump. I did that on the basis that if I needed to run the engine to charge batteries, I could make water for 'free' at the same time. That worked quite well on a transat, and the water maker made about 60/hr.

 

[dgadee]

PTO from the main engine driving a CAT 277 pump. I did that on the basis that if I needed to run the engine to charge batteries, I could make water for 'free' at the same time. That worked quite well on a transat, and the water maker made about 60/hr.

Ah, I think I asked you that a couple of years ago when I was putting mine together. I am 1hp single phase but decided to try 1 to 3 phase invertor and three phase motor. I also want to use a 12v to 240v inverter for when I am motoring. All maybe a bit more complicated - and more to go wrong - than your setup. I have two pressure vessels and get about 120l per hour.

 

[geem]

PTO from the main engine driving a CAT 277 pump. I did that on the basis that if I needed to run the engine to charge batteries, I could make water for 'free' at the same time. That worked quite well on a transat, and the water maker made about 60/hr.

Engine driven watermakers are a great idea if you dont have a genset. If you are sat in an anchorage for a few weeks it makes a lot more sense to run a genset than your main engine for battery charging with a three stage charger, make water and hot water via the immersion heater.
The problem with engine driven and only a single membrane is if you are only making 60 litres/ hr you will have a lot of engine run time at minimal load. Not a great utilisation of your engine. We have three membranes installed. It uses no more power to make 200 litres as it does to make 60 litres via our genset. It uses the same 1.5kw motor on the Cat 247 pump either way.

 

[Goldie]

PTO from the main engine driving a CAT 277 pump.

That’s what our system does. System is by Aquafresh but the brand has now been taken on by Osmotech at Hamble Pt.

 

[geem]

That’s what our system does. System is by Aquafresh but the brand has now been taken on by Osmotech at Hamble Pt.

I built mine myself. Cat 247 pump, 1.5kw motor, two 40” membranes and one 21” membrane, 220v feed pump that also does deck wash. Super simple system with no electronics. I am the control system?

 

[dgadee]

I used a General Pump WM1615 because I was doing a reverse engineer. That was a bit of a mistake since it then tied me into a US flange size (56C) for which motors were impossible to find in Europe. However, it all works with what I got (1hp). Knowing what I know now I would have used a European pump and gone 3 phase first of all - that would have meant I did not have to find a low power startup motor . I run off a Honda Eu20i generator. I bought a Silverline 2000 watt inverter but it won't start the present motor. It does start the crew's hairdryer, though. A new pure sine wave inverter has been bought, so we will see if it works with the new system.

 

[jdc]

Another thought for the OP: this forum has several members who have constructed - and full marks to them for effort, ingenuity and parsimony - a water maker which uses two pumps: a low-pressure one followed by an old-fashioned, noisy and inefficient high-pressure pump, few, if any, of which were designed for use in salt water. These often are sourced from pressure washers.

On the other hand most modern water-makers (Spectra, EcoHydro etc) use a purely mechanical device to make the high pressures from the low pressure feed pump alone. This is energetically possible for water makers as they all need a fairly high bypass ratio (although tbh I don't understand the full physics of the limits, high and low, of this factor). It's called a Clark Pump, and makes for quieter, more energetically efficient and more reliable operation.

The trade-off is home made, and so money saving (and - a real plus point this - you fully understand it) versus a bought but higher tech product. I can't say which will appeal to the OP more. For me, although I have made several things for the boat myself so was tempted to go for the home-brew version of the water-maker, energetic efficiency was the deciding factor. Hence the Spectra.