Étude – Making Water

“Making water”. Sounds kind of like magic, doesn’t it? Well it’s not magic, it’s misrepresentation. Water-making is really water filtering, and it’s energy-intensive which is why we’re not all drinking the Pacific Ocean.

Creating drinking water to rival any bottled product from plain old sea water is just a process of sucking up liquid from a hole in the bottom of the boat and passing it through a series of finer-and-finer filters to eliminate whatever sea life was unfortunate enough to be floating nearby. The “magic” happens at the end when the water is forced at high pressure through a membrane that allows water to pass, but not the salt or other things we don’t like to drink.

It used to be that a watermaker required a fair amount of maintenance. As you can imagine, the stuff that failed to pass through the membrane accumulates. Cleaning was a frequent chore. Now, thanks to the miracle of computers, that’s done as required automatically. Not to say that a modern watermaker is maintenance-free, there are still four filters and a sea strainer to be cleaned.

An additional bit of “magic” is that the process can be powered by 12 volts of DC current. This means that one can run the watermaker while underway, powering the process with the engine’s alternator. In the case of our watermaker, a four hour cruise would create 60 gallons (225 liters) of fresh water.

These are not my photos, they were sent by the Nordic factory to show where they planned to install the various watermaker bits and pieces. The photo above is of the main control unit. It holds the high-pressure pump, the computer, and has the primary and secondary (gross and fine) filters mounted on its side.

To the left in the photo below is a “thru-hull” (hole through the hull, duh) where the sea water is sucked into the watermaker. Some thought needs to be given to the location of this hole. Putting it immediately aft of the sewage discharge would be bad.

Note: sewage discharge is only allowed in a limited number of places in Canadian waters and not at all in Puget Sound.

This is the “sea strainer” and its attached pump. The strainer is the first level of filtration and gets all the stuff one can easily see: plant material, sand, bits of shells, unfortunate small sea life.

The water next passes through the Plankton filter (not yet mounted in the photo) and on to the primary and secondary filters. They trap successively smaller impurities, leaving the membrane to deal with chemicals and minerals in the water. The membrane is held in the longer black tube.

Here’s how it all fits together. We are looking into the lazarette, which you may recall will eventually be covered by the cockpit. That’s the open area at the aft end of the boat.

Here’s a broader photo showing both the future cockpit and the saloon. The plywood covers access to the area where the heating system, hot water tank and fuel tanks live. Note the exhaust pipe on the starboard side of the lazarette.

That’s it for water-making. Stay tuned for the next post, which documents a major milestone.

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