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**Tellie** · 05-10-2009, 08:06

Quote:

Originally Posted by thatboatguy

One last thing... can I look through your box of "didn't work so well" when we come down this winter? heh heh

George

I believe the bag of water up the mast was posted here on CF awhile back. The tow behinds are fairly impractical for most. Can't make a lot of water with them at anchor.
...and yes you can have a look. I have offered before here, that anyone who's looking to make their own WM should put up a want list of parts and that perhaps I might have a part or two that will suit them for cheap. I guess I should just compile a list and post them.

canucksailor · 05-10-2009, 09:16

Interesting thread - you guys have some amazing info....I read somewhere of inexpensive 120 volt units meant for non marine use....cheap, like $300 or something foolish like that. At that price, even if it lasted a year, you'd be getting off cheaply. I could see buying a small genset - say a 1300, they cost about $200, and using that for watermaking to spare the diesel.

Wally

**anjou** · 05-10-2009, 09:18

ive had a good day as I went to see a hydraulic firm i used to use for repairs and parts years ago, chatted to one of the guys about desalination. He keeps tropical fish at home and has to pass tap water through a membrane to remove chemicals etc, so was not only clued in but very helpfull. Hes going to look for a pump which will deliver the pressure and volume needed with the most economical motor for the job.

They also sell pressure guages, by pass valves, pressure regulators etc as well as prefilter polycarb bodies and elements.

WHat he did say was, most pressure washer pumps now run at 1500 ish PSI and are usually coupled to larger 2kw single phase or 3 phase 240v motors and so i need to find an older type pump that only delivers 800 ish PSI, which then will be ok on a 24v motor. Also newer pumps are designed to give more pressure but use less water, so its going to be running a lot longer to get the throughput, bearing in mind you need to pass 5 times the total volume compared to the final product volume.

Finding the right pump is the key, after that, the anciliaries are more easilly sourced

**anjou** · 05-10-2009, 09:20

Quote:

Originally Posted by canucksailor

Interesting thread - you guys have some amazing info....I read somewhere of inexpensive 120 volt units meant for non marine use....cheap, like $300 or something foolish like that. At that price, even if it lasted a year, you'd be getting off cheaply. I could see buying a small genset - say a 1300, they cost about $200, and using that for watermaking to spare the diesel.

Wally

But a non marine type unit wont desalinate. to remove salt, you have to pass water through a membrane thats even finer than a virus molecule, and that can only be done with high pressure.

canucksailor · 05-10-2009, 09:30

...see what I mean, you guys have all the answers. Thanks, I'll follow this thread as I'm interested in one day having a watermaker, without the cost of buying one.

Wally

thatboatguy · 05-10-2009, 09:38

I wish we could take Tellie's post a few above and make it a "Read this first" somehow. A very good summary.

George

**hellosailor** · 05-10-2009, 10:02

So, George, you have to use Miracle Whip instead of mayonnaise?? (G)

At a certain point one has to wonder if it wouldn't be simpler to skip the membranes, use wind/solar/genset power to hydrolize sea water, let the H+O recombine, and collect the nice pure drinking water from that.

I'd hate to think of what the energy bill would be...but I suppose part of the "bang" could be used for getting some of the power back out of it, too.

"Dop you have any weapons on board?" BOOM! BOOM BOOM BOOM!
"No sir, that's just the watermaker."

Ahuh.

goboatingnow · 05-10-2009, 11:20

Quote:

WHat he did say was, most pressure washer pumps now run at 1500 ish PSI and are usually coupled to larger 2kw single phase or 3 phase 240v motors and so i need to find an older type pump that only delivers 800 ish PSI, which then will be ok on a 24v motor. Also newer pumps are designed to give more pressure but use less water, so its going to be running a lot longer to get the throughput, bearing in mind you need to pass 5 times the total volume compared to the final product volume

your expert doesnt really know that much, the PSI output of a displacement pump is a max rated number, the actual PSI developed is a function of the pressure regulator, a 1500 PSI pump will happily generate a system pressure of 800psi, or anything from zero to max rated ( assumming you can supply the input power).

Thoughput is a function of the displacement of the pump and the speed it runs at again a function of the max rating the pump can take and the available power source.

**s/v Jedi** · 05-10-2009, 14:28

Guys,

That "how to build to own watermaker" PDF linked to earlier in this thread is quite a good document. It also explains why it's better to put the membranes in series for the high pressure plumbing. There's some things in there that I think can be done better, like using a March pump as boost-pump and flushing by using the boat's pressurized fresh water system instead of always messing with a bucket. But the principles and components description looks good to me!

cheers,
Nick.

**anjou** · 05-10-2009, 15:09

Quote:

Originally Posted by goboatingnow

your expert doesnt really know that much, the PSI output of a displacement pump is a max rated number, the actual PSI developed is a function of the pressure regulator, a 1500 PSI pump will happily generate a system pressure of 800psi, or anything from zero to max rated ( assumming you can supply the input power).

Thoughput is a function of the displacement of the pump and the speed it runs at again a function of the max rating the pump can take and the available power source.

Sorry, im having a blonde moment, can you say that again in a diferent way cos i dont understand

**s/v Jedi** · 05-10-2009, 15:33

What he means is that when you leave the pump's outlet open, you get 0 psi regardless of the pump's rating. It's only when you almost close it's outlet using a pressure regulating valve, you get the high pressure. That valve can be adjusted so that you create 800 psi pressure from a pump that's rated for 1500 psi. My AquaPro titanium pump goes well beyond 1000 psi but I operate it around 800 psi that way.

cheers,
Nick.

SV THIRD DAY · 05-10-2009, 16:11

We have a home build 50GPH water maker aboard THIRD DAY and love it. The 6.5hp kubota diesel off ebay for $500, $1000 high pressure water pump, and $800 for two 40in membranes and pressure vessels. Everything else is just was off the shelf parts that came to maybe $1000 tops. We may not have the fastest, newest, prettiest boat, but we haven't came across a 36ft boat with a water maker as big as ours!

You can see photo and info about it here:

View topic - Frankenmaker progress : Cruisers Forum : Latitudes & Attitudes Magazine

and

View topic - Frankenmaker MK II : Cruisers Forum : Latitudes & Attitudes Magazine

Rich
SV THIRD DAY
Blog:Today or Tomarrow | SV THIRD DAY

thatboatguy · 05-10-2009, 17:05

Hey Rich! I've already posted those links but thanks for the plug.

Everybody this is Rich Boren, my partner in crime.

George

Martinini · 05-10-2009, 17:20

Take a look at this How To Make Your Own Watermaker Instructions

svcattales · 05-10-2009, 19:20

This company has good prices for modular H2O makers and I saw the 10GPH on Ebay for $2,600. Clean Water, Water Treatment, Home Water Cleaners, Quality Water Works Inc., Winston-Salem, NC They also use a Wanner Hydra Cell pump for high pressure pump as I did in my system. I chose a lower output (6.5gph) so I could use a 12V motor to drive the pump instead of an 120V motor.