What to do about Water? tankage, requirements, watermakers.... etc.

[matt195583]

Just to add something to the earlier part of this thread. The Guy who owns the 30 footer i would like to buy had a built in tank in the bow . he was not happy with the quality of the water sot he cut the top out of the tank and got a Turtle Pac custom made to fit the space. this has been in place for 5 odd years and he is extremely happy with it. One other thing he told me is that Turtle pac made 3 tanks before they were happy with the fit in the space. He only paid for one.

[Old Shoe]

That's handy information. Thanks.

[Bubba the Pirate]

Squirreling away bottled water is a decent idea, but the empty bottles should be squirreled away as well until you reach some destination where you are capable of recycling said bottles. 

My current philosophy is to try to eliminate as much waste/trash/recyclables before I leave.  I will likely use some jerry jugs or collapsible tanks to augment my water tank.


Todd

[Old Shoe]

Are you kidding?  :)  I'd never throw my water bottles overboard, or anything else for that matter. And, since the whole Ches. Bay is soon to be a total NDZ, the only place I'll empty my head is during the Atlantic leg if I'm far enough out.

[Skipper Dan]

Just to add to this thread a little. I am new here and used to be in water treatment. It is not that hard to make an RO that would work. I am not by the ocean so it will be hard for me to test it other than trying to make some sea water. RO's have come a long way and you do not need all that much pressure. One of the 12 vlt pump should work just fine. Total cost should be less than $300.00 including pump. Add a UV unit for a little more.

Dan

[CapnK]

Welcome to sailFar Dan :) I think it would be very interesting topic, your knowledge about making a small & simple 12V RO watermaker. I am clueless about them, pretty much, other than a general knowledge of how they work, so feel free to share - if it is not too complicated, I *am* near the ocean, and would give it a try. :)

Would you necessarily have to use an electric pump, or could you use pressure developed by a hand pump, say for instance like the pump on those garden sprayers?

[LooseMoose]

Well color me VERY interested on where you can pick up the components for a watermaker for around $300. I've been pricing out the various bits and I can't seem to get the overall price below $1200.

Maybe I'm looking in the wrong places?

Do point us in the right direction...

Bob

http://boatbits.blogspot.com/
http://fishingundersail.blogspot.com/
http://islandgourmand.blogspot.com/

[Capt. Tony]

I have no idea what a decent pressure rated 12V pump draws but it probably falls outside my energy budget.  I do know that R.O. membranes are far more efficient as the supplied water pressure approaches 100PSI.  So I dont think a simple (or should I say readily available) hand pump will do the trick.  Even your low GPD membranes still like high pressure for efficiency. 

I used to want a watermaker on board.  Now I think they would be a maintenance hog for a small boat.  I work with several everyday and have built all but our first one.  They are simple in design and construction.  At work, here, they get used a lot and that affords us the opportunity to keep the membranes flushed and we switch out the 0.5 micron carbon blocks as needed to prevent chemical degradation.  On a boat, I think keeping the unit flushed, keeping the prefilter from clogging and preventing biological degradation of the membrane just makes them more work than they are worth.

Having said that, a hand pump unit might be a life saver in a ditch kit.

[CapnK]

1) What is "GPD"?

2) "Biological degradation" - sounds like you mean "stuff in the water growing on/clogging up" the membrane? Do you just wipe that off, or flip the membrane and use pressure to get rid of it? How hard is it to do?

3) Is the process of desalination somewhat like charging a battery to 100%? Where the first 80-90% of the process is relatively quick and easy to complete, but getting that last 10% of salt out is a good 50%+ of the effort? (Told you I was clueless. ;D )

OK, the thought occurs - I should do some research/reading - 'cause I am asking the noob questions that people in the know hate to hear over and over... :)

[LooseMoose]

Here is a link to a very simple and basic DIY watermaker...

http://www.westward-ii.com/PDF%27s/D%20I%20Y%20Watermaker.pdf

Bob

http://boatbits.blogspot.com/
http://fishingundersail.blogspot.com/
http://islandgourmand.blogspot.com/

[CapnK]

..and here's a $200 (!!!) water-making beach ball...

http://www.landfallnavigation.com/memss.html?

I know that if you are floating in a life raft, thirsty and have no water to drink, that you would burn $1000 bills for a cuppa fresh water.

But do they really have to charge $200 for this $0.35 plastic thing? Ridiculous.

Here's something that begs for a reverse-engineered, KISS, Creative Commons solution for the masses...

[Capt. Tony]

That does seem a little high for a 'beach ball'!!!  Scale of economy hard at work there.  I gotta think a distiller would be one of the first things I set to work after immediate medical attention once adrift.

GPD is gallons per day.  Under lab. conditions your typical 25gpd membrane will give you about 20 gallons of good 'product' water and 100 gallons of waste/reject water.  That is why we run recapturing loops and extra membranes here, but, I still loath the waste. Granted, on a boat the waste merely returns to the sea.
Product water is an actual yeild vs. theoretical yeild.  Variables that influence product output of a membrane are temperature, pressure and disolved solids in the input water.  The last of these would be a concern.

Biological degradation is 'cooties' growing on the membrane and  in the membrane housing that actually breakdown and compromise the intergrety of the Thin Film Composite membrane that does the 'separating' against the concentration gradient.

You can't backflush a membrane like yu can some types of filters.  'Flushing' an R.O. membrane is really rinsing off the outside of the membrane in situ on a regular intervals.

Again, it's not that I don't think they work, it's just gravitating away from K.I.S.S. principles.

[Skipper Dan]

Here is a link to a very simple and basic DIY watermaker...

http://www.westward-ii.com/PDF%27s/D%20I%20Y%20Watermaker.pdf

Bob

http://boatbits.blogspot.com/
http://fishingundersail.blogspot.com/
http://islandgourmand.blogspot.com/

That is way to much stuff. most if not all is not needed. you need a simple 12vt pump, membrane housing, prefilter and some kind of germ treatment, (UV, Ozone, Chlorine, Or just boil it. I will work on this today and see what I come up with. As with anything sold over the counter they have to many goodies attached. As far as a hand pump every thing helps create pressure. If you pump up a tank with water and air you have a certain amount of PSI. Put a pump after that and it adds to the total. Put two pumps inline and you now have twice the PSI. Put a pump on your engine and you can get plenty of PSI and charge the battery to boot. Also the more flow you run to drain the cleaner the membrane will stay but the more water you will use. A membrane works on high side pressure vs low side pressure. The pure water will migrate to the low side by osmosis. If you totally plug up the drain you will just have a big filter and it will plug up rather quickly. More water running across the membrane keeps the contaminates flowing to drain.

Dan

[LooseMoose]

Dan... My bad I thought you were talking about a watermaker  for $300 as opposed to a water filter system in which case $300 is something like over kill as the Sawyer (http://www.sawyer.com/products.htm) provides all the filtering anyone would would need fr between $50-$130 off the shelf ( and good for a million gallons!)

The DIY system I linked to is a watermaker capable of turning seawater into freshwater and while it can be simplified a bit you still have to deal with a high pressure pump, some means to drive it and a membrane in a pressure vessel.

Bob

http://boatbits.blogspot.com/
http://fishingundersail.blogspot.com/
http://islandgourmand.blogspot.com/

[Skipper Dan]

Bob I was, but I did run into a snag. It could have been a misprint in my catalog. I had seen a 1.8" membrane listed now I cannot find it. Doing an online search the smallest I found was 2.5"x 14" membrane alone is $168.00. A pressure vessel is $200.00 something. But this is a 150 gpd RO. You need 300 psi which is not hard to do with a RO booster pump. I am still going to keep looking. The big RO's they are quoting are for lots of water and we only need gallons per day. I still have plenty of contacts in the industry so I may get some answers. Housings are not that hard to make. I will only need a valve on the drain to regulate pressure.

Dan

[skylark]

How do you store water aboard?  Do you have permanently mounted tanks? bladders?

How much tankage is enough for staying aboard for longer periods?

Do you use water jugs?  What size?

How do you fill the tanks or jugs?

[CharlieJ]

Aboard Tehani we have two tanks, both bladders. 27 gallons under the cockpit and about 17 or 18 up forward for a total of 35 gallons. Laura also stows 1 and 1/2 gallon jugs in various places around the boat, depending on where we need trim ballast.

When we head out to prmitive anchorages, we carry an extra 5'or 10 gallons in folding jugs storeroom the cockpit seats against the cabin. Nothing on deck-ever.

We figure we can stay away from civilization for about a month with no particular extreme water saving measures.

We carry 4 foldable 5 gallon jugs for refilling tanks when we carry water in the dinghy.

As a matter of practice, we try to refill when the after tank is empty when we can.

[Tim]

Aboard Tehani we have two tanks, both bladders. 27 gallons under the cockpit and about 17 or 18 up forward for a total of 35 gallons. Laura also stows 1 and 1/2 gallon jugs in various places around the boat, depending on where we need trim ballast.

Mariah carries  about the same in bladders, but I have maintained the raw water thru hull for rinsing, washing etc.  Since  she will most likely only be seeing coastal cruising, this seems adequate.

[Godot]

Back when I was planning on building a boat, I thought it would be a good idea to just keep a five gallon (or whatever was appropriate) jerry jug plummed straight to the sink, with spares kept in storage.  Coincidentally, Loose Moose just had a blog post describing the exact same system (http://boatbits.blogspot.com/2011/02/simple-water-system.html).  Godot currently has a twenty gallon tank under the v-berth.  I think the jerry jug system is better.

[Auspicious]

I have never heard anyone say they had too much water capacity.