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Old 03-09-2010, 14:20   #1
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Question Potable Water Tank Material

After a botched epoxy coating job on the existing aluminum tanks on our '78 Westsail 43 by the previous owner we now have crazy algae infused bubbles and hence a need for drastic measures. This is going to be a fairly intensive project so am looking to do something that is cost effective yet enduring, the tipping point... Seeing the way these tanks have weathered their 30+ year existence i am a bit reticent to replace with new aluminum but see its price point far below that of stainless, though not necessarily potable. The fiberglass/epoxy option seems strong enough, if properly build and painted could it hold 130 gal? Or would it be possible to correctly epoxy a new aluminum tank and enjoy its structural strength? what are the thoughts out there on best material for potable tanks, keeping in mind they are anything but standard sizes?
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Old 03-09-2010, 14:57   #2
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Why can't you have a tailor made plastic tank. These folk are UK based but there must be a simlar US tank manufacturer.

Tek-Group Ltd Tek-Tanks

I have had to replace an aliminium water tank in a previous boat, like you I won't have another and stainless steel is getting expensive this side of the pond too.

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Old 03-09-2010, 15:49   #3
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these guys are in California and have hundreds of styles/sizes.

Ronco Plastics - Marine Water Tanks, RV Water Tank, Auto Detail Tanks, Water Tanks
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Old 03-09-2010, 16:38   #4
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Welded polyethyene?

I had a tank made up by a local shop here in Sydney from welded polyethylene. Fitted under the forward cabin berth.

Cost (from memory) about $800au.

No worries with taste or quality.
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Old 03-09-2010, 16:52   #5
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FWIW Gougeon Brothers do not recommend their epoxy for potable water tanks;

EPOXYWORKS

"We have adopted the broad policy of not recommending epoxy for drinking water tanks because of regulatory and safety issues. The potential problems outweigh the benefits. To date, none of Gougeon Brothers' epoxies meet FDA regulations or any other drinking water certified approval. The major long-term concern with any plastic water tank is extractives leaching out in the water. Off-ratio, poorly cured epoxy can release extractives, as noted above. In the fabrication of water tanks and food handling equipment, the successful use of epoxy requires thorough mixing and adequate elevated temperature post-cure to assure the maximum cross-linking and cure of the polymer. These process controls are not always possible with the home-built tank."

I don't know if other epoxy manufacturers have similar reservations but would not be surprised if they do. I originally planned to build my own but decided on plastic after reading the above.

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Old 03-09-2010, 16:54   #6
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Further to Borcat's post, plastic welding is quite easy, and the tool used is not expensive. Making a suitable tank is a worthwhile DIY project. Try Googling ' Hot air plastic welding' and you will fine plenty of info.
Regards, Richard.
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Old 03-09-2010, 17:35   #7
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Thanks for posting that, Mike. Looks like I'll be getting plastic tanks too. The problem with the Ronco tanks is they don't have baffles as far as I know, so I'm looking for another USA supplier.

Do you have a supplier who has plastic tanks with baffles?

Quote:
Originally Posted by mikereed100 View Post
FWIW Gougeon Brothers do not recommend their epoxy for potable water tanks;

EPOXYWORKS

"We have adopted the broad policy of not recommending epoxy for drinking water tanks because of regulatory and safety issues. The potential problems outweigh the benefits. To date, none of Gougeon Brothers' epoxies meet FDA regulations or any other drinking water certified approval. The major long-term concern with any plastic water tank is extractives leaching out in the water. Off-ratio, poorly cured epoxy can release extractives, as noted above. In the fabrication of water tanks and food handling equipment, the successful use of epoxy requires thorough mixing and adequate elevated temperature post-cure to assure the maximum cross-linking and cure of the polymer. These process controls are not always possible with the home-built tank."

I don't know if other epoxy manufacturers have similar reservations but would not be surprised if they do. I originally planned to build my own but decided on plastic after reading the above.

Mike
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Old 03-09-2010, 20:15   #8
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Quote:
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Thanks for posting that, Mike. Looks like I'll be getting plastic tanks too. The problem with the Ronco tanks is they don't have baffles as far as I know, so I'm looking for another USA supplier.

Do you have a supplier who has plastic tanks with baffles?
I don't believe there is such a beast. I suppose this is as much to do with manufacturing difficulties as with lack of concern with "foaming" of water as opposed to diesel. If noise is a concern you could use multiple smaller tanks. I have unbaffled plastic tanks on my Catalina and they are very well mannered.

I need to come up with tanks for my cat and was planning on just using what stock tanks I could find, but Richard's post about making your own has got me thinking.

Mike
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Old 03-09-2010, 22:49   #9
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I don't believe there is such a beast. I suppose this is as much to do with manufacturing difficulties as with lack of concern with "foaming" of water as opposed to diesel. If noise is a concern you could use multiple smaller tanks. I have unbaffled plastic tanks on my Catalina and they are very well mannered.

I need to come up with tanks for my cat and was planning on just using what stock tanks I could find, but Richard's post about making your own has got me thinking.

Mike
If you are OK with unbaffled tanks, you can probably find some at Ronco for your cat. They have a lot of stock tanks.

My concern with unbaffled tanks is for both noise and strength, especially with the tanks I will need which will be about 6 feet long, fore and aft. Are the tanks in your Catalina that long?
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Old 04-09-2010, 03:44   #10
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For what it's worth, I've had plastic (HDPE) welded tanks made and they have baffles.
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Old 04-09-2010, 06:00   #11
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Tank baffles are used to control liquid surge.

LIQUID TANK BAFFLES

The “Trail Creek Baffling Strips” demonstrated in the above article could be easily home fabricated, for use in un-baffled plastic tanks.

Liquid stabilizing baffle system - US Patent 6308856 Full Text
Jim Spickelmire
Trail Creek Inc.
617 Cunningham
P.O. Box 66
Grangeville, ID 83530
Web site: http://www.trailcreekinc.com
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Old 04-09-2010, 07:24   #12
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For a 130 gal tank, at least one baffle is what I'd recommend. I'd also recommend at least 2 inspection ports and substantial support and securing measures. A 130 gal tank is about 1000 pounds of water. One thing you might consider is 2 65gal tanks.

When My fw tank went south after 20+ years, I put in an aluminum one primarily due to structural issues. Nowadays, I'd probably go for the welded plastic but oversize the material and reinforce the corners and bottom.
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Old 04-09-2010, 10:58   #13
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Sounds like plastic is the go to these days. Very little noise from the metal camp...
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Old 04-09-2010, 20:26   #14
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langdonpierce,
I just coated my starboard tank with FDA approved epoxy in my water tank. It is potable water certified and is fairly easy to apply. It needs to be 20 to 40 mils thick after your done. The only thing is that you need to have the boat empty or tent the area and blow the fumes out of the boat. I know it doesn't seem like it is FDA approved if you need an organic chemical mask to apply it but it is. Go to www.armorpools.com
If you need any questions answered, PM me and we'll talk
WD
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