CONFIGURATION
POSSIBILITIES
Changes as of 4/2024
Boost pump - Jabsco Water Puppy Bronze Pump or
Groco Continuous Duty Centrifugal Pump - CP-20
There is no single right way to configure all boats to make
water. There is just the right way for
you and for your circumstances. You
could go with 12 volt, engine driven or a 110 motor, with multiple membranes or
just one, or with automated controls or manual.
You could even use a hand pump to make fresh water from salt water, if you
are trying to stay in shape, take very few showers and plan to do nothing else
with your time. But then you would not
be reading this post.
We have our reasons for the choice of configuration we made,
or at least ended up with. Some things
at the start were different than at the end.
But it works for us and you have to figure out what will work for
you. As we describe our configuration,
we will try to also give reasons, which may help you make decisions as to your
particular setup.
*** Whatever you do, it is yours
to do. We have simply described our setup after multiple requests for this information from cruisers. We are not responsible for your
work! ***
OUR CONFIGURATION
Our first time cruising was on the U.S. west coast and in
the Sea of Cortez back in the 90’s. We
had a small 12 volt water maker that produced under a gallon an hour. We supplemented this noisy trickle by
purchasing questionable water from local sources and hauling it back to the
boat in our dinghy. In setting up our
second cruising boat, many things we previously considered luxuries were
promoted to necessities. Having a lot of
water on board was at the top of the list.
As many of our sailing friends know, we are not in a perfect sailing world. We may have to turn on the engine until the
wind comes up or after the wind dies out.
We have found this to be true especially in the Bahamas and the eastern U.S. Based upon the fact that we recognized
motoring would be a part of our cruising life, that we did not have a built in
generator, and that we wanted to make a lot of water per hour, we chose the way
of an engine driven water maker.
We have an 80 HP Ford Lehman motor in Hold Fast. That motor lugs along and presents no
noticeable difference in performance if we were to run a pump to push water
through one membrane or through three.
We found a bulkhead where we could mount three membranes and it seemed
to us that three was better than one.
Not only could we make 55 or 60 gallons per hour with three membranes as
opposed to 24 GPH with one, but it would also allow us some redundancy in the
event one of the membranes failed.
There are nice 12 volt systems out there than almost run
themselves. They run for a period of
time and then flush themselves. On Hold
Fast, we have tankage for almost 300 gallons of water. This allows us a period of two weeks or so
between making water. Given that simple
is better when building something yourself and that manual is more simple than
automated, our system is manual. First
of all, there is no clutch on the pressure pump. When we want to make water, the engine is
shut off and the belt is installed, then the engine is turned back on. To stop making water, same thing: engine off,
belt removed, and the engine is restarted unless we are sailing. Secondly, all product water goes down the
sink until our total dissolved solids reads 300 or less AND the water has been
personally tasted and approved by the captain.
Once approved, the product water is manually switched to fill one of the
three tanks aboard Hold Fast. And
finally, we flush the system by manually turning a valve and turning the water
on for a timed period, the timing of which is dependent upon whether it is an
initial flush after making water or a secondary flush.
Now you see the reasons for our choice of an engine driven,
three membrane, manually operated water maker system. We also have a secondary RO water system for
drinking and cooking water, but that is a matter for a different post.
PARTS LIST
Feeder Pump – We have a Shurflo Blaster 3.5 Washdown
Pump, purchased from West Marine. It
pumps 3.5 gallons per minute. We no
longer see the part number sold, but a pump along these specifications will do
the job. The primary concern with this
pump is that it must have output that is greater than the input requirement of
the pressure pump. The pressure pump must
never run without water. In our manual
process, the feeder pump is turned on before we start the motor and turned off
only after the motor is stopped. We put
a Y-Valve on the feeder pump and use it alternatively as a wash down pump. We did not choose a centrifugal pump, as that
type of pump can sometimes lose its prime.
We are on our fourth year utilizing the same pump for both wash down and
to supply water to the pressure pump.
20 Micron Filter Housing and Filters – The raw water
must be filtered of any large particulates that might damage the high pressure
pump. Our 20 micron filter is the first
in a series of two. We purchased the
housings and all our filters at US Water Systems, particularly Harmsco Water
Better pleated filters SKU 545-WB-20W.
Their inexpensive filter housings are just under $12 each.
5 Micron Filter Housing and Filters – The 5 micron
filter is the second in the series of two between the feeder pump and the high
pressure pump. Again the housing and
filters were purchased at US Water Systems, only the 5 micron filter is SKU
545-WB-5W.
Here is a picture of the Filter Housings. The Feeder Pump (Blaster) is below the housings with a yellow handle on the valve to select water maker or wash down.
Here is a picture of the Filter Housings. The Feeder Pump (Blaster) is below the housings with a yellow handle on the valve to select water maker or wash down.
Pressure Pump – We used General Pump, model number
TT941, with a flow of 3.43 gallons per minute at 2,800 RPM. It was purchased from
Pressure Washer Authority. This pump
is a forged brass manifold pump. We know
it will not last the life of the membranes, but at $232.99 each, you can easily
carry a spare (or two) as opposed to paying about $1,500 for a stainless or bronze
pump. This pump has lasted 10 years and made over 10,000 gallons of water as of 4/2024.
Alternatively, Model TT9111 ($248), which runs at 3 GPM,
should match up with some electric motors if your configuration involves a
generator. If you plan to start with one
membrane and expand, you should consider the small additional cost of a higher
flow pump. Dow Water and Process Solutions has a free software for download: Dow R.O.S.A System Design Software, that you may use to help size
your pump.
Here is a picture of the Pressure Pump with belt installed for operation:
Here is a picture of the Pressure Pump with belt installed for operation:
Engine Bracket – This part of the installation
required some technical expertise in designing the pump bracket. We laid out where we wanted the pump and the
pulley alignment, and then drew the bracket design. We had our friend and master craftsman, Rich
on Morning Star, tack together the bracket, which we then installed, made some
adjustments, and then had him weld it together.
Membranes and Housings – Our membranes are 2.5 inches
by 40 inches, purchased from American RO, part number SW30-2540. The price for the membrane is $180 for quantities
1 through 5. The housing we used,
PV-2540-SW (ACT) cost about $415 each.
We got the ACT ends because they will not corrode in our environment, which
is a possibility with the aluminum ends.
As a side note, American RO also had a link to the Dow R.O.S.A System Design Software, something mentioned above.
As a side note, American RO also had a link to the Dow R.O.S.A System Design Software, something mentioned above.
Mounts – We used pipe wall mounting hardware from
McMaster Carr to secure the membrane housings to the bulkhead. Our best space on the Whitby42 was below the galley
floor just forward of the engine room.
Here is a picture of where we mounted the membrane housings. You can also see the blue pressure tank for the secondary RO system, again a subject for a different post. 
High Pressure Line and Fittings – After measuring the
lengths required, we ordered high pressure braided chemical hose, SKU 52515K3,
FDA food grade, from McMaster Carr. We
used the brass flared fittings. These
same items may also be ordered from Discount Hydraulic Hose.
Pressure Gage – The control of pressure controls the
quantity of water produced. We ordered
our high pressure gauge from McMaster Carr.
The gauge goes up to 1,000 PSI and is glycerin filled.
Needle Valve – The needle valve is used to increase
or decrease the pressure on the membranes.
We now use a 316 stainless steel needle valve called a Mini Valve,
purchased from McMaster Carr for about $62, part number 7833K96. We recommend 316 stainless because we tried a
brass needle valve and it did not last very long.
Water Quality Monitor – Our water quality monitor is
inline and gives the total dissolved solids of the water exiting all the membranes. We purchased this quality monitor from Wateranywhere. It is a Dual Total Dissolved Solids Meter
(Dual TDS) made by HM Digital, part number DM-1 at about $30. You could use something similar, like an SM-1
which is $25. Or you could use a hand
held meter, but we wanted ours inline, and the price is not that much
different.
Flow Meter – Our flow meter shows how many gallons of
product water are flowing out of the membranes.
We did not put a meter on the flow of the brine water. Ours is a panel mount flow meter made by King
Instrument Company that shows up to 75 GPH.
We purchased it from McMaster Carr for about $58. You can select Part #4351K121, and then you
must choose the flow rate to suit the system you are building. A meter with a smaller flow rate could be
used for a one or two membrane system.
Coconut Charcoal Filters – You will need a filter fit
for removing chlorine from your tank water for the flushing of the pressure pump
and the membranes. It is prudent to
always assume that chlorinated water has made its way into and resides in your
tanks. We use a coconut charcoal filter
purchased from the same place as our other filters, US Water Systems.
OPERATION
Start Up – As mentioned earlier, before start up of
the engine, the belt is put on the high pressure pump and the feeder pump is
turned on. We check to make sure the
feeder pump is working water through the system by confirming that water is
flowing out the brine through-hole and that there are no air bubbles. The portion of the system that feeds water to
the high pressure pump is visually observed for leaks. Once the engine is started and engine specs
check out normal, the RPM is brought up to 1,300 or just below. The high pressure pump is designed to run at
2,800 RPM, therefore we sized the pulley on the high pressure pump so that the
RPM on the Lehman would be 1,300 RPM, a good motoring speed for Hold Fast,
which would run the high pressure pump at 2,800 RPM. This 1,300 RPM represents the top end limit
for motoring when we are making water.
Applying Pressure – By turning in the needle valve,
pressure is increased to the membranes.
Dow recommends you take 60 seconds to bring the membranes up to operating
pressure. If you are using your
membranes for the first time, you should consider taking two minutes. Operating pressure for us depends upon the
salinity of the water. We bring it up to
make 50 gallons an hour and let it stabilize for about 10 seconds, making sure
the pressure on the guage never goes over 1,000 PSI. Normally the pressure is 750 to 800 PSI. Once stabilized, the needle valve is again turned
in until we get 55 to 60 gallons per hour and that is normally at 800 PSI. If we only had one membrane, the rate would
be about 24 GPH, and if we had two membranes, the rate would be about 40 to 42
GPH.
Product Water to Tanks – Once the water maker is producing
55 gallons per hour, the Dual TDS Monitor is turned on. When it is first turned on, the TDS will read
somewhere above 300, but it will quickly move down to 300. When it hits 300, the water is tasted, if it
tastes good the water is diverted from the sink to the tank. A note is made as to the rate of water
production, say 55 gallons per hour, and a timer is set. We have our ways of knowing when each tank is
full. A valve is turned to change which
tank receives water until we have made our desired amount of water, or until
all the tanks are full, or until we are done motoring.
Here is a picture of the TDS Monitor, Flow Meter, Needle Valve and Pressure Gauge. Please note this picture was taken while we were making water on the Chesapeake, which has less salt and requires less pressure (under 400) and the water product has fewer TDS (061 parts per million).
The picture below was taken when making water during a passage from Provincetown, MA to Shelburne, NS. The water temperature was about 47F. In accordance with the membrane manufacturer's specifications, cooler water will give a product with less TDS. The rate of production is just under 60 GPH, at a pressure of around 750, producing water with 114 TDS.
Here is a picture of the TDS Monitor, Flow Meter, Needle Valve and Pressure Gauge. Please note this picture was taken while we were making water on the Chesapeake, which has less salt and requires less pressure (under 400) and the water product has fewer TDS (061 parts per million).
The picture below was taken when making water during a passage from Provincetown, MA to Shelburne, NS. The water temperature was about 47F. In accordance with the membrane manufacturer's specifications, cooler water will give a product with less TDS. The rate of production is just under 60 GPH, at a pressure of around 750, producing water with 114 TDS.
Please note, when the membranes are used for the first time
after pickling or the first time ever, it will take 45 minutes (or more) to
clear the pickling solution from the system.
We flush after pickling only using the feeder pump, as recommended by
Dow.
Shut Down – Prior to shutting down the water maker,
the product water is diverted to the sink again and the needle valve is slowly
backed out, taking about 60 seconds to do so.
With the needle valve completely back out, the system is run for 3 to 5
minutes, giving the system a saltwater flush.
Flushing – Within 24 hours of running the water
maker, both pre-filters are removed and rinsed with fresh water. The charcoal filter is placed in one of the
pre-filter housings. The tank water is used to flush approximately seven
gallons through the system. The charcoal
filter typically flows at one gallon per minute, therefore the flush lasts
seven minutes. After flushing, the
charcoal filter is removed and rinsed with fresh water.
PICKLING
Whether or not we are away for the summer, we still pickle
the water maker system once each year.
The annual pickling is recommended by Dow to keep the biological count
down in the membranes. We use the same product
used in the wine industry. It is called Sodium
Metabisulphite and we purchased it in bulk from LD Carlson Company out of Kent,
OH. We say ‘in bulk’ because what was
delivered to us will last ten years or more since we only use 2 ounces per
gallon of water and it only takes five gallons per pickle (or ten ounces of
sodium metabisulphite). If you have a
pressure pump from Spectra, DO NOT use this chemical for pickling, it will
damage the pump. There are no
pre-filters in the housings when we pickle.
COMMENTS
We have no delusions that we have answered all your
questions. You must spend time to study
the subject on your own. If something we
have written seems unclear, please leave us a comment on the blog along with
your email address. We would be glad to
get back to you.
May you have fair winds, following seas and fresh water.
