Watermaker

S

Shadowcruzr

Active member
exMember
Joined
Jan 1, 2000
RO Number
1702
Messages
1,621
Looking for a watermaker recommendation for a 1976 Hatteras 48 LRC for an extended trip into the Bahamas and Virgin Islands.

2 adults onboard, lots of washdowns and occasional laundry. Owner is a clean freak. His nickname is Capt Swiffer.
 
Nice boat, we almost bought one but the new paint job was flawed. Anyway, we have been struggling with village marine and note their membranes are not industry standard size. They have so far made good on free upgrades and a few membrane swaps. Think 3M or GE I believe who manufacture the same sizes and are interchanable.

Given the input I'm thinking a large unit and 220v. 10-14 gph isn't enough for them.
 
how much water you make per hour will be driven by how much time you will be in open ocean or relatively clean harbor water each day and how much time you will be on generator/shore power each day. based on your description you will likely need to make on average some where around 75-100 gallons per day of water. more on laundry days. if you are on shore power at all times in very clean harbor you can use a smaller GPH unit 7-12 GPH size. if you only want to run the generator a few hours a day and need to be on the ocean to get clean water something in the 20-30 GPH will work. the membranes are extremely sensitive to dirt so clean water is paramount. best way is to use large multistage prefilters and not run the unit in an area that has silt or any kind of pollution like unburned fuel/soot etc.
 
good point water quality although typically in the bahamas and in the islands you spend quite most of the time in clean anchorages. In most marinas i dont run the WM although it depends on where you are, sometimes i run the WM on an incoming tide. another concern besides oil is bacteria from waste... i dont' really trust that others won't discharge!

if they have room (I'm guessing they do in an LRC with smaller engines), make sure they get the larger prefilters. again, in the bahamas i've gone weeks without having to replace them, but in some places the smaller ones get dirty in as little as 5 hours.
 
Don't forget to include a portable tester of some sort. This way the quality can be measured to ensure a certain amount of safety.
 
Remember, reverse osmosis involves forcing water molecules through a filter to remove the aqueous salt. The salt size is about 0.001 microns (micron is one millionth of a meter) and cannot pass through the membrane. But water molecules are much smaller at about 140 picometers will pass through the membrane, 1 picometer is 1*10^-12 meters.

Pathogenic bacteria, bacteria that causes infectious diseases range in size from 0.2-0.6 microns, viruses range from 0.02-0.03 microns...........they will not get through the membrane. A reverse osmosis system will remove virtually all pathogens from drinking water. The water produced by reverse osmosis is practically pure water. I plan to use ultraviolet filtering in my system to protect against surprises. Dissolved substances need to be absorbed by activated carbon which I will use.

OK, although I believe it is safe to use an RO system at the dock, there are things to watch out for obviously. Things that don't pass though the membrane can certainly plug it up. So good filtering before the membrane is needed. My intention is to use a combo of a 10 or 5 micron in front of a 1 micron. Again, this is just my goal, if there is too much pressure dropped at the 1 micron filter, I will be forced to go to something larger. Have not yet gotten to the filtering part of my design.

Foggy
 
Thats why my Spectra unit has the optional Z Brane unit to protect from pathogens and also cloging the membranes from biological growth. My unit works well in Brackish water but the pre-filters need more attention when used in Brackish water.
Bill
 
I use the standard 20 micron followed by a 5 micron filter assembly recommended by Spectra. I also have the active filter off of the stariner to catch fuel contaminated water as a precaution.
Bill
 
quote:
Originally posted by Billylll

I use the standard 20 micron followed by a 5 micron filter assembly recommended by Spectra.
Click to expand...


+1

Bob
 
I use a schenker, had a pur previously. It makes 8 gallons an hour, far below your needs. the unit worked fine for 4 years now and was my sole source of water during that time. Spectra and schenker require a little over 1 amp hour per gallon. Village marine is a joke (sorry, but its true). What you need is an engine driven unit. These typically make 60 to 100 gallons per hour and have far less trouble then an electric unit like spectra, schenker, village marine. Many places make these or you can do it yourself by buying the pump, a few valves and as many membranes as needed for your needs. You could also easily cut back on your water use. 4 gallons a day per person will include laundry, showers and an easy life style if you use the water wisely. I know people doing it on 1 gallon a day but they subsitute salt water and I don't like that. I would have used an engine run watermaker myself but I don't run the engine (sailboat) and don't want to just to make water. A power boat doesn't have this issue. If you go electric you'll need to run the engine to charge the batteries and it will be about twice the cost. JMO
 
Engine driven watermakers also have problems. For example, the output from a pump is directly related to RPMs so the engine's RPM must be controlled. There is also the mechanical challenge with belts, pullys along with mounting which is not small by any means. But life is filled with trade offs. One needs to weigh his needs against cost, hourly product and other associated factors. There is no one ideal solution. OH, electric operation is not limited to charging batteries. I have a 2HP electric motor for my high pressure pump that will be powered from my 7.5KW generator.

Foggy
 
THanks you all for some great info and insight. Don (the Hatteras owner) is greatful as well. It is really helping him in makeing a decision. I'll let you know what he decides on.
If you have any more info please send it along.
 
Having been living with Village Marine for 2 years now, Peleka summed up their capabilities well, at least in our instance. Others are happy with them but they don't even test their water quality.
Now that we are 220 VAC, I can at least switch to another membrane and pressure vessel to see if that helps.

Any thoughts on the other membrane manufacturers?
 
You must log in or register to reply here.
Back
Top