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John MacDougall, Annie Laurie, #26

Hello to all.....

Deciding on whether, or not, to purchase and install a watermaker for your sailboat is a subjective decision, and not one taken lightly, especially considering the $5000 - $10,000 price tag.

There is a LOT of information out there (some of it is good, but not all of it!) regarding watermakers, their longevity, their maintenance troubles, their installation, etc. And, if you talk to the manufactures AND the cruisers that have (and use) watermakers, you'll find there are 5 or 6 true facts that most will agree on:

- The #1 reason for watermaker troubles is: the lack of use.
- This can be caused by a few things, most probably the owners didn't understand their needs or the "needs" of the watermaker, BEFORE they bought / installed one.
- High Efficiency (gallons of fresh water produced versus the electrical power used) costs MONEY.
- Automatic operation / ease of use, costs more MONEY.
- Newer, More Efficient (GPH / Electric Power) Watermakers mean that 12vdc power can be used even for larger, 300 - 400 Gallon Per Day (GPD) units, BUT that might be way too large of unit for most.
- Good manufacturer (and installer) support is very important.

So, while I don't wish to sound too much like an expert, nor confuse things too much, here's what my 4 - 5 years of research and asking a LOT of questions have come up with:

- Decide on HOW MUCH WATER you need to make and remember that if you're used to conserving water, you may end up using 20% - 30% more water, AFTER you've got a good working watermaker on board. How much water you need to make, is a number with a denominator, such as 100 gallons per week, or 20 gallons per day, etc..
- Determine the size (and style) of watermaker you need.....("GPD" = gallons per day, is the typical spec used to compare watermakers, even though you may never actually run the unit for 24 hours straight). The BIGGEST watermaker you should ever choose is one that will allow you to USE IT and make fresh water, at least EVERY 5 days. That doesn't mean you need to drain your tanks dry, NOR do you NEED to wait 5 days between watermarking cycles. BUT, what it does mean, is that YOUR on-board lifestyle (especially your electrical power available) is what should determine the size (and style) of your watermaker.....and NOT me, nor a salesman at a boat show!!! Also the space you actually have available, of course.) This is SO IMPORTANT, I'm going to repeat it: YOUR on-board lifestyle (especially your electrical power available) is what should determine the size (and style) of watermaker for you....NOT me, NOT a salesman at a boat show!
- Even though it's just some plumbing and 12vdc wiring, actually installing a watermaker in a mid-sized sailboat (such as our Catalina 470's) can be very tricky and VERY time consuming. If you've got a lot of other systems on-board (as I do), such as a genset, 3 A/C units, aux bilge pumps, lots of tools, spare parts, equipment, hurricane anchor and rode, sea anchor, drogue, spinnaker, etc. etc. etc.....just finding the space for a watermaker can be tricky.

I did quite a bit of looking around, and found the main bilge area to be large enough for a small (150 - 200 GPD) watermaker......AND still allow EASY access to it, AND to ALL other systems in the bilge (raw water strainer for A/C units, genset Racor, bilge pumps and float switches, hoses and wiring, etc.). Using this area, keeps you from reducing storage space elsewhere, as well as keeping everything in a central location and allowing for a concise hook-up / installation. (also keeps any leaks in the bilge, and keeps added weight low in the hull.)

- Some may want to use the area under the forward bunk, but I chose NOT to, since I have a Fischer Panda Genset, and 2 of my A/C units mounted there, as well as use the remaining area for storage. Another area, is under the dinette seats.....but I use those for storage as well. Others (especially those skinny and wiry owners) may wish to mount a watermaker in the lazarette, BUT I'd not advise it since you WILL need to service it and going in/out of the lazarette is a pain (not to mention the need to protect a watermaker from flying objects throw into the lazarette).
- Purchase a watermaker from a factory trained and certified installer, even if you've decided to install it yourself.....(you'll be very glad you did!) I chose to have my unit professional installed by the dealer who sold it to me. I was there on board the whole time (staying out-of-the-way), and ran the power wires / hooked up a new circuit breaker myself weeks before the watermaker installation. I was able to see how it all fit, and how it all goes together....and how to get at everything to test / service it. It was NOT complicated, and I feel I COULD have done it all myself, BUT it would've been a pain...and I'm GLAD I paid the money to have it installed professionally.
- Go with a popular, name-brand unit and especially one from a manufacturer that has an excellent reputation and customer support!

Having already decided to purchase a High-Efficiency unit (such as a Spectra or new HRO unit). In my situation the AMOUNT of water I needed to make was a SECONDARY factor in determining what size and style watermaker. My MAIN factor was the ability to make water WITHOUT any significant impact on electrical power, thereby eliminating any necessity to run the Yanmar or Fischer Panda just to make water (or to charge batteries, after making water), this also complimented my requirement to have a watermaker that I would use regularly.

Having a large solar array (520 watts), and a towed-water-generator for use on long passages (no photos yet, but just get in touch for the details), made my choice of a 12 Volt DC watermaker easy!

Keeping all my water tanks intact (at least for now!) allows me to store and carry 200+ gallons of fresh water, and using only approx. 10 - 15 gallons of water per day, means that if I got a big watermaker (300+ GPD), I'd not use it too often and its power consumption (~ 20 amps) would take most of solar panel output, not allowing much for battery charging on that particular day.

And then the third determining factor, the SPACE I had available, came into play.

And last, but certainly NOT the least factor...... Ability to be easily maintained! Yes, I wanted a EASY TO MAINTAIN foolish am I???? Well the truth is that if you actually use a watermaker properly (use it often and keep the filters clean), and use a fresh water flush (which does use some of your precious fresh water) on a regular basis, you'll find maintenance to be minor......typically just changing the pre-filters!!

And when I added up the different factors, for my boat and my on-board lifestyle, here's what I got:

- A high-efficiency 12 volt DC unit, one that make a gallon of water on about 1.2 - 1.4 amps of 12 volts (costs extra $$$).
- A 150 - 200 GPD (6 - 8 gallons per hour) unit, allowing me to run the unit for 3 - 6 hours, every other day (or so) during good battery charging time (higher voltage = higher efficiency).
- A unit that would FIT under the main salon cabin sole, in the bilge, allowing ease of use and servicing, AND NOT interfere with anything else on board.
- A unit with automatic control functions, especially an automatic fresh-water flush every 5 days but can still function in a manual mode (costs more extra $$$).
- A unit with good manufacturer support.

So, I chose the Spectra Ventura 150 MPC. A 150 gallon per day unit, that draws about 8 amps @ 12 volts, and makes about 6.5 gallons per hour. (I've actually seen mine do as much as 7.4 GPH, see the photo.) It will FIT in the bilge area, under the main salon cabin sole, AND allow for ease of service and access to everything else as well. It has a fully automatic control, as well as the ability to use it manually, completely without any control panel. Should the automatic functions fail, you can still make water the old fashioned way...LOL. Spectra WILL stand behind their product, and has a reputation of excellent customer support.

I took the photos of my installation, prior to cleaning up the bilge, but they show the installation is very well done, and even though you can't tell, it DOES allow for easy servicing.

I hope you all enjoy.

(Click on picture for full size)


Intial mounting


Intial mounting, feed pump


Final install under main salon sole (in bilge)


Final Install (in bilge)


Final Install (pre-filters)


Final install (feed pump + filters)


Final Install (product water into tank manifold)


Control panel


7.4 GPH


Salinity 248 PPM