Re: [PUP] watermaker recommendations
We have had good luck with our no frills manual control 24 volt Village
Marine 8 GPH unit. We only have made about 4000 gallons so far but no
worries yet.
The VM is not as efficient as the Spectra as it requires about 20
watts/gallon whereas the Spectra is closer to 12 watts/gal. The Sea Recovery
units are in the order of 25-30 watts/gal. On sailboat's this makes a
difference but on a trawler not as much. We are aware of many folks who have
had issues with the Spectra and are not happy. Spectra's support is good but
if you are out of fresh water in outlying cruising areas or on a passage you
are SOL.
Village Marine's Little Wonder is really a minimalist unit like the
Katadyn's and as such is better suited to sail boaters needs, IMO. I.e. 5-10
gallons a day consumption..
I think the SCCA's list is skewed towards low power/production units as you
typically find in sailboats. So their experiences are not really as
applicable to trawler folks.
You need to understand your freshwater needs before you start shopping for
units. Trying to have a small unit make 200 GPD every day is not going to
work. OTOH, getting an 6-800 GPD unit will lead to maintenance & operational
issues if you only use 20 GPD. What power source(s) do you have and wish to
use to run it. DC is generally available at any time. The larger AC units
can run on inverter but consume so much that you'll need the genset on more
often that not to use an AC powered one. What is your charge regime on your
vessel? How does "making water" fit into it? Many questions ;-)
The units need to be run every three days to keep the water in them fresh
and for a few hours from our experiences. Yes some do have automatic systems
that will circulate, back flush and wash your back if you want but these all
add a level on complexity that invariable reduces the MTBF.
We run ours about 10 hours every 3 days which keeps it fresh, keeps the
water in our tanks fresh and keeps even with our 25 GPD consumption while
cruising.
As always YMMV....
Dave & Nancy
Swan Song
Roughwater 58
I'm glad this topic came up. One thing I've neglected to get a handle on is
my watermaker. The PO put a Katadyne PUR160 on the boat. We have yet to
settle into a charging cycle or to fully understand our water needs.
Someone a few months ago advised there were two things to NEVER discuss with
the wife. One was water useage and the other escapes me? Now don't get me
wrong, my wife thinks she uses water conservatively, but I suspect her idea
of conserving is very different that Patrick G.'s. We routinely run through
260 gallons of water in 4 days. This is without being conservative at all.
We take showers, wash dishes without soaking in saltwater first, we usually
take on water at a marina. So, in the back of my mind I've always thought I
be replaceing the watermaker with one of the newfangled units that flushes
itself every 3 days and is smarter than I am. Dave's caution about going
overboard on it are valuable, but there does seem to be some advantage in
selecting an intelligent unit. So here are some additional questions
someone may be able to help me with:
a. My manual says the watermaker can only make water from Clean, Open Ocean
seawater. It cautions against making water anywhere near land. If your on
the hook for a week, how to you make water? Do you use it as an excuse to
go to sea and fish for a few hours?
b. In this scenario, do you size the watermaker 2 or 3 times larger than
you would if you planed to be voyaging every other day for 10 hours or so?
I can see that the time you make water and the quantity are critical in
sizing. Is there a good compromise?
c. Is there any such thing as a set it and forget it watermaker? Mine is
in the lazarette and it's a PITA to get to. The thought I have to crawl
back there and flip valves open and closed is enough to make me sea sick.
Also, the amount of space dedicated to hoses and plumbing takes a lot of
storage away. But, on the other hand at least I can see everything!
d. Finally, would you try to make the PUR160 work, or would you vote in
favor of upgrading to a Village Marine with enough capacity to make 15 or 20
gallons per hour?
Thanks much,
Scott Bulger, Alanui, N40, Seattle WA
3 mi offshore San Francisco on the way to Half Moon Bay
My manual says the watermaker can only make
water from Clean, Open Ocean seawater.
Oil and chlorine will destroy the membrane over time,
grit and sand will clog it. As Dave Cooper said, a
pre-filter is invaluable. I have not seen a modern
watermaker installation without a pre-filter, so you
likely have one. Chances are, you'll know when it's
okay to run your watermaker just by looking out your
windows and surveying the environment.
I can see that the time you make water and the
quantity are critical in sizing.
I couldn't agree more! Rather than look at the
gallons-per-day rating, I'd say get the largest unit
(within reason) you can afford and will fit, then
budget your consumption to equal 2-4 hours per day of
running. Except for short run times, even the
low-power 12V units (160 gpd) will need a generator to
back it up. And most cruisers are underway under 5% of
the time, so 2-4 hours of watermaking a day will allow
long runs to catch-up. (e.g. 160gpd = 7 gph, so budget
25-30 gallons/day; 600 gpd = 25 gph, budget 100-200
gallons/day).
Is there any such thing as a set it and forget
it watermaker?
The modern watermakers are pretty well set/forget.
When you want to make water, you turn-on a switch at a
control panel. There's not much reason to go below and
fiddle with the valves, though it should be part of
your normal engine room check while running. And if
you move from warm water to cool water, the
hi-pressure valve may need some adjusting.
Finally, would you try to make the PUR160 work,
or would you vote in favor of upgrading to a
Village Marine with enoughcapacity to make 15 or 20
gallons per hour?
Personally, I'd make the one you have work. I don't
know the PUR so can't comment on it's durability, but
all watermakers seem fairly high maintenance
(especially those that aren't used daily). But if you
do replace (and are okay with the expense), go for at
least 300 gpd ---- if you have the space.
Overall, it appears watermakers benefit from heavy
use. I met one guy in the Caribbean who had been
cruising 20-years with the same watermaker, using it
almost exclusively for water due to the high cost of
marinas and water. His watermaker was rusty, and
occasionally cantankerous, but ran like a top. Like so
many other things on a boat, lay-up causes
deterioration.
Peter
Willard 36 (with watermaker)
San Francsico