WATER TANKS

[Tantramar]

I have a sailboat with two 200 liter Plastimo flexible water tanks (bladders). They are fairly new but require continual patching due to leaks that develop. Although I am becoming quite accomplished at this it is time to move on. I looked at water tanks from Ronco and they appear to be good but even with their extensive selection of sizes the most I can fit in the existing lockers would be two 120 liter units at $384.00 each (plus shipping, exchange, etc.) I am considering building tanks that actually fit the lockers so I can maximize the available space and have increased water storage. My idea is to buy 4' x 8' sheets of 3/16" fiberglass, cut it into panels then fiberglass the joints (from both inside and outside) to form tanks close to the desired shape (no compound curves). I think this would work but I am concerned about the residual fiberglass odour that I am sure the stored water would absorb. There must be coating available that would seal the fiberglass and it would have to be "food quality" so the water in the tanks doesn't become contaminated. Does anyone out there have any experience with this, suggestions or ideas?

[wrwakefield]

Tantramar,

You can create truly waterproof and odor-free tanks by coating the inside with epoxy. [The odors come from polyester resin...]

Although the epoxy manufacturers don't recommend this because some individuals may not wash off the amine blush, I know several individuals who did and have great results over the years. It may be one needs a 'food grade' epoxy product to avoid the disclaimers.

Here is West Systems write-up regarding this.

You could also weld your own polyethylene sheets and perhaps get even better results.

Cheers!

Bill

[Cheechako]

There are places that will custom build plastic ones not too bad a price either. Tank depot?
I have found fiberglass tanks in boats I've had terrible smelling/tasting. If the right Gel is used maybe better but frankly, why do all that work and be disappointed.

[bil56]

for not having unpleasant odor or taste, use an epoxy resin and a special coating for food products.
Another solution is to build tanks in welded PE plastic.
don't forget the anti-roll partition bulkheads

[peghall]

Welding PE isn't as easy as most people think till they've tried to do it. There's more to it than just melting the edges and sticking 'em together...you have to know how much of each edge to melt and also inject new melted material to blend with the melted edges so it all runs together into a single reinforced mass. Leaks are common in DIY welded PE tanks. PP is a lot easier to cut and it can be "glued."

I'd go with 3/8" polypropylene instead of FG. That's what Triple-M Plastics uses for their custom welded water and waste tanks, which are rated top quality. They have a pretty good series of photographs showing how they do it on their website:
Triple 'M' Plastics » Our Process

Knowing which "glue" to use may be the most important thing to know.

[Grateful]

MAS claims that their Epoxy has no amine blush. I'm using the product to build some holding tanks, but I really don't car whether or not the resin imparts an off taste ;-)

[lonesoldier0408]

I'll have to research it further, but I had a, "Spray in bedliner," sprayed into my 07 Dodge 3500. 3/8ths inch thick + or -. No smell, that I can recall. Anything placed on it wouldn't move. I did spill bleach on it and can't recall where exactly, also can't see where it was spilled.

[CGirvan]

I'm considering a similar project incorporating the boats hull and plywood bulkheads, bonding with epoxy resin. I got some good info on this site:

Atom Voyages - Integral Watertank Construction

Also intend using this paint for the inside lining:

Low VOC, FDA rated epoxy coating for brewery tanks linings, potable water tanks and food processing.

Hope this helps.

Colin