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Nauticatarcher · 29-12-2007, 10:20

Quote:

Originally Posted by exposure

Rough calculations for the pump are about 3hp required. This is over 2000 watts or over 150 amps with a 100% efficient motor. Even if I am off by a factor of two, 75 amps is not practical for an electrical system on a boat. It must be engine driven.

Woody

Most power calculations for HP pumps are for continuous use at max rated pressure, running a 3000 psi pump at 750-900 psi will be possible with less horse power, on our unit the manufacturer's rating is for 3hp for 2000 psi but we get by with 2hp and I reckon 1.5hp would do as we run 2 4' membranes we only run it one hour a day for 120l of water, our 2400W inverter will start and run motor and if we are doing alot of motoring we can do it that way without having to run genset.
One thing with watermaker membranes is to avoid fouling they like a raw water flow of approx 10 to 15 times there product rate, generally a 4' membrane will produce on average 1lmin even though in manufacturer's ideal world it's rated at 1.5lmin, output is affected by raw water temperature and salinity and it is a good idea to have a flow guage on product water side to make sure you dont exceed max rated flow for membrane which will irrepairably damage it if you try to run it in water that has too low a salinity, eg around river mouths etc.
FILMTEC MEMBRANE DISTRIBUTOR has best price for membranes and pressure vessels that I know of. you want a SW2540 for a 4' unit

jheldatksuedu · 29-12-2007, 13:07

I just found this on another thread. Not a watermaker but could be a life saver. It produces a salt free energy drink from seawater without work. Called forward osmosis.

http://www.noonsite.com/General/Safety/SeaPack

Randyonr3 · 29-12-2007, 19:30

When it all comes down to money spent and what you get out of it, remember, you get what you payed for.. and yes, you can build your own watermaker, but you have to drive it. and most of the time your not sailing, your at anchor, so it cost fuel to run it, now its a loss.. The "water log" works well while your sailing, but not at anchor..
The ideal unit is one that will run off the boats electrical system and re-charge with solar or wind-charger..
This is what many watermaker companys are looking for... a system that does not strain the boats power systems.....
I sell and service Spectra Watermakers.. and yes,they are pricy. But you push a button and they work, and the more they work, the better they work.. The only mantiance is periodioc cleaning of the pre-filters.. And the wife loves it.......

jheldatksuedu · 29-12-2007, 23:28

Concerning building your own system, money is not the only thing to enter in the equation. I enjoy learning a system inside out, the way you have to when you build something up from scratch, I feel I'm a better judge of what I need than somebody else that has to design and build for the masses. For me when I'm at anchor I can haul water from shore, granted most people are not like me, I'm a strange duck in pond full of swans that is for sure. I'll admit not many 45 foot sailboats have a full machine shop on board or a 10 kw generator and an arc welder, but I do. I feel the need for a water maker is when you're at sea, far from land, but if I decide to need it at anchor I only need to add a low pressure pump to make it work there also. If I built it I sure know how to service it, that to me is most important in a cruising sailboat. That is also how I've managed to get where I'm at with very little money. Thanks for your input, I will admit it applies to most, but maybe not me.

Sometimes you get more than what you pay for. At least I always try my darndest too... Now about the wife, maybe that's why I'm still looking... Somewhere there is a swan for me....

Randyonr3 · 30-12-2007, 08:19

I think building your own systems is great, I've re-built everything on this boat,
And the funny thing is, I was planning on doing the same thing you are, building my own system.. A great part of being able to cruise is to be able to repair what you have, or build it..
Short story, I stopped in Spectra watermakers to pick their brains about the systems and how they work.. I had also mentioned that I had built my own systems throughout the boat.. They made an offer to me.. to teach me how the system works from one end to the other. in detail, over 40 hours (5 days-8hours) in class room form.. sell me a system AT COST, and let me go cruising..
Spectra has odd way of dealing with service and repairs by training 4 to 6 people each year that are out cruising or have plans to cruise. you become a roving dealer, and operate within the cruising community, thus, taking care of the service for spectra and get this.. I'm now making a few EXTRA bucks while I cruise..
A half a dozzen times over the past 4 years I've pulled in some place and run across someone looking to install a watermaker.. So I get the sale, and most of the time, the instalation and a enough money to keep me going for another couple months... pretty good exchange in my book.
I stock enough parts to rebuild a couple units and a pretty good stock of Pre-filters...
I keep in contact with Spectra and all the roving dealers are listed so if a repair is called into the office, the word gos out to the dealers and the one closest has the option to do the repairs... so as I travel around the world, spectra will help support the trip, and at the same time, spectra dealers are out there to service units..
If you have the skills to build your own system, you also have the skills to repair and service other units... you might give it some thought.

jheldatksuedu · 30-12-2007, 08:39

Interesting
I think I might look into it. Thanks. Jon

**GordMay** · 30-12-2007, 11:10

Spectra Roving Technicians
Spectra has them! These folks perform a valuable service for us as they cruise the world’s waters providing repair, advice and parts for our customers. These technicians have attended our “Watermaker 101” school to become proficient in the application, repair and maintenance of Spectra watermakers. They have often assisted us in resolving a technical or installation problem that would have been difficult for the yacht owner to deal with. Many of these representatives have sold and installed systems making a few dollars to fatten the cruising kitty. This program has been so successful that we areminded cruising people to provide service in remote parts of the world.
If you are mechanically inclined, have the time to be trained and are interested in joining the Spectra team please contact our manager of technical services, Glenn Bashforth.
Phone: (415) 526-2780
Fax: (415) 526-2787
Email: techsupport@spectrawatermakers.com

Watermakers 101: PowerPoint Presentation

jheldatksuedu · 30-12-2007, 14:56

Thanks for the info on Spectra, I'll check it out.

I'm also planning on learning more about the sea-pack stuff and figure out what's in the sugar solution, should be no reason I can't make that up myself. I think one unit would last a lifetime.
Sea-Pack Emergency Desalinator

dpex · 13-01-2010, 22:03

I'm warming to the idea of DIY especially because, a while ago I bought...simply because it was available cheap.... an Italian, single cylinder diesel (12hp and affectionately known as an "Old Thumper") which uses about .6 litres per hour.

My original thought was to use it installed in a box on the fore-deck for my anchor winch.

And so, here's the question a) Given OT maxes out at about 1200rpm, is likely to shatter the deck at 200rpm (Hence "Old Thumper") and runs smooth as a nut at 900rpm....can I gear up a pulley arrangement to drive the pump from a water-blaster unit?...BTW: damn clever thought, that one.

Qb) What other components are required? I know I need a filtered water supply, and an SS tube for the RO filter, a method of back-flushing the RO filter, and an outlet for the fresh water. Apart from these bits, what else is needed?

Randyonr3 · 14-01-2010, 08:18

something to think about.. the system of using a RO filter works off of preasure and not volumn.. your pump may put out large amounts of water but will it develope the preasure needed to opperate..
The system I use has a pump that delivers around 100 psi to the clark pump which multiplys the preasure up to around 900 psi.. Thats the force it takes to push water through 2 24 inch filters and gives me 6 gallons per hour.. and even though we use the term "Back Flush" when you build your own system, you dont want to back flush it.. just set up a valve to switch from salt water to fresh and flush the system.. put the valve between the pre filters and the pump and pull the fresh water off the tank..
Thats one of the draw backs to using a system as mine that only delivers 6 gph as it takes about 5 gallons to flush the system.. so I allways waste a 5 gallons of water after filling my tanks just cleaning up the system..
when you flush the system, all you are doing is cleaning the membrane of salt.. when pumping in fresh water, it will wash the membrane..

Brent Swain · 14-01-2010, 14:10

Quote:

Originally Posted by Randyonr3

When it all comes down to money spent and what you get out of it, remember, you get what you payed for.. and yes, you can build your own watermaker, but you have to drive it. and most of the time your not sailing, your at anchor, so it cost fuel to run it, now its a loss.. The "water log" works well while your sailing, but not at anchor..
The ideal unit is one that will run off the boats electrical system and re-charge with solar or wind-charger..
This is what many watermaker companys are looking for... a system that does not strain the boats power systems.....
I sell and service Spectra Watermakers.. and yes,they are pricy. But you push a button and they work, and the more they work, the better they work.. The only mantiance is periodioc cleaning of the pre-filters.. And the wife loves it.......

"You get what you pay for" is a used car salesman's line, used to sell lemons to suckers. Don't be such a sucker as to always believe that line, or your cruising will cost you far more than it needs to, and like the suckers who believe that line , you will spend a lot more time on the treadmill, lining the pockets of marine equivalents of used car salesmen, and a lot less time cruising.

dennisail · 06-06-2010, 15:14

Any news on cheap water makers?

dennisail · 06-06-2010, 15:40

Reckon you could just feed a RO membrane with something like this pressure cleaner? At this price they are disposable. 1350W 95gph 1400psi $100. Would it last any length of time flowing salt water if you flushed it with fresh water after each use?

How much does the membrane cost? House hold ones are around $100. But I take it they wont be any good with salt water...

1350W High Pressure Cleaner Water Blaster -360L/Hour - eBay Pressure Washers, Outdoor Power Equipment, Gardening, Home. (end time 04-Jul-10 12:46:38 AEST)

I found that original pump here for $237 free shipping in US. Would probably cost me over $400 by the time I had it here. Then I have to find a way to run it.

http://www.pressurewasherauthority.c...mp-tt9111.html