Originally Posted by noelex 77
This shows how you need to think about how you will power the watermaker as a first step.
I live on board the boat permanently and make 95% of my water via the watermaker, but as a sail much more than I motor. I only average 80hrs a year on the motor.
My requirements mean the power consumption
of the watermaker are much more important than Oceansailor.
So I have chosen a power recovery watermaker (spectra) while Oceansailors requirements are very different.
If your boat is set up for solar or/and wind
power and want to avoid engine hours a power recovery watermaker is the right choice.
But if your battery
and watertanks are sized accordingly you can save money avoiding a recovery watermaker.
As 90 % of my energy is generated from the engine, I decided 20 or 40Ah does not really matters. Energy has to be replaced by the engine. As the Echotec was half the price
compared with a power recovery watermaker, I had money to install a second alternator instead. This means I fill my batteries faster as before the installation
of the watermaker. As a bonus I have redundency for the alternators. I have the same engine hours as before the watermaker!
My battery bank is 900 Ah. If I come to an anchorage and the batteries are full, I can run the watermaker whitout the engine for 3 -4 hours. This I do if I will motor next day. Running the engine only for watermaking would be inefficent use of the engine.
Last 6 month of cruising ( full time on the boat ) I had 120 engine hours. During the same time I had 141 hours of watermaker time. ( 7050l of water)
Compared with the recovery models the Echotec is much more basic. No salinity probes etc. Not one sensor in the unit. Belive me that is an advantage in the long run! There is not much that can go wrong on a basic watermaker. The only negative is that the are noisy compared with the recovery models.
My last advice. Buy as much capacity as you can afford from the beginning. Most people I have met say the same thing. "I should have bought a unit with more capacity"