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wgh52 · 01-11-2012, 16:02

I'm in the process of replacing my 30 year old stainless steel water tanks which have developed a leak. My initial thought was to replace with new stainless tanks, however, someone in the boat yard mentioned that their boat had fiberglass tanks. I'm wondering the pros and con's of fiberglass versus stainless steel. The tanks are under the teak and holly sole so this is not something I would like to do this again anytime soon.

I thought the experience of this group might help me with this decision.

Seren y Mor · 01-11-2012, 16:19

Maybe not fibreglass but certainly polypropylene. Some manufacturers are now using this medium due to lower cost, lower weight and the ability to be formed easier to complicated shapes.

I have made some myself and can certainly say it's a better replacement . . . BUT . . . I already had and could use the "heat gun" equipment and knew how to weld metals. The construction technique, you see, is similar.

With a special foot to the gun you weld a profile of PP to the seams of two pieces to weld them together. As in welding steel cleanliness ans some beveling may be required. Before welding on the tops the "baffles" actually stiffen the construction as well as adding any other support needed. Where inlets and outlets are needed the PP thickness is once again stiffened by welding on a patch of PP before the holes are cut. Access panels using gasket material are no problem either.

Remember this material simply bends to any curve easily unlike steel which needs tool forming! So . . . you make the tank/s fit the full space available. No need to be concerned about reliability, when the job is done simply use a simple pressure tester over a set period and you'll know if you have any leaks.

Good luck with your search!

Target9000 · 01-11-2012, 16:22

I would take poly over SS. Wouldn't bother with actual fiberglassing.

**David M** · 01-11-2012, 16:29

Polyethylene does not leave a taste nor does it oxidize. You can also get them in a huge variety of shapes and sizes.

LakeSuperior · 01-11-2012, 17:11

Make the tank out of monel, it will last forever!

marshmat · 02-11-2012, 09:52

For fresh water, linear polyethylene would be my first choice. Easy to fabricate, not too pricey, darn near indestructible in normal use.

I'd consider fibreglass for built-in tanks where the rest of the structure is also composites, but they are labour-intensive.

For integral tanks in a metal boat, the same metal as the hull is the obvious choice. I don't see any reason to choose metal otherwise- aluminum, SS and steel all have potential corrosion issues that require careful design and fastidious installation to avoid, and monel is expensive.

Polyethylene (linear for water, x-linked for fuel) is simultaneously the easy, cheap and long-lived choice in many applications.

Stumble · 02-11-2012, 11:01

WGH,

I would go poly unless you have some specific reason not too. The ease of installation and lightweight make them my favorites.

Most metals are frankly unsutable for water tank usage (stainless, Monel, and aluminium) and are at best a problem waiting to happen, with a lifespan of "how well was it installed, and how many unexpected issues will you have." I have seen aluminium tanks that needed replacing in 5 years due to corrosion, and stainless that lates as little as 7. On the other hand yours lasted 35, so who knows. I you want to go metal I would of course recommend titanium (not nearly as expensive as many think) but metal tanks wouldn't be my first choice really.

**minaret** · 02-11-2012, 21:56

A properly built fiberglass tank will last forever, and is the best option out there IMHO. Of course it is also the most expensive. I've seen too many failed welds in poly tanks for my taste.

tunnels · 04-11-2012, 21:45

As a fibreglass person i would suggest stainless with a guarentee !!
glass tanks for fuel and waste water ok not a problem but the only glass tank i would drink out of would want to be a fully hot air welded hippoline plastic tank with a glass reinforced outside .! the cost and making you could probably buy two s/s tanks !!

HopCar · 04-11-2012, 21:57

This is the place to buy water and holding tanks. Ronco Plastics - Marine Water Tanks, RV Water Tank, Auto Detail Tanks, Water Tanks
My Ronco water tanks are over twenty years old and like new.
I believe these tanks are roto molded not welded. They have about 450 different sizes and shapes.

tunnels · 04-11-2012, 22:06

Yip that even better !! deffinately not glass tanks to drink out of !! no way !!

**minaret** · 04-11-2012, 23:21

Yes, but roto molded tanks have no baffles and are therefore only good up to a fairly small size. Fine for small boats. There are some great epoxy coatings for the inside of water tanks, FDA approved. No chemical taste at all. I have built some very high end examples.