Tanks, tanks & more tanks

[knottybuoyz]

So decision time. The kid is entering an industrial metal fabrication and welding trade school in the fall. I've spoken to another father who's son was in this program a few years ago and he had them fabricate a number of items in their shop class. He paid for the materials, gave them the basic dimensions and they did the design and fabrication. I'm considering doing the same if we can. So can I have them make aluminum tanks for fuel, fresh water and waste? The tanks will be approx. 35 gal, .125 5052 marine grade aluminum. I've heard aluminum tanks aren't all that great if you put clorinated water in them so should I stick with a poly tank for F/W?

[Stranded Mariner]

Why would you use aluminium tanks? If you want to go for metal tanks, I would suggest stainless steel.

[knottybuoyz]

Originally Posted by Stranded Mariner

Why would you use aluminium tanks? If you want to go for metal tanks, I would suggest stainless steel.

I don't know. What would be the cost difference?

[Alan Wheeler]

Difference in cost is staggering. The SST being very expensive. Aly is fine for all tanks except blackwater. It is too acidic and I am not sure I would want to trust SST in that role either. Although you could internally coat it with a liquid rubber type coating, Like PRC or similar liquid coating. Aly is certainly light and easy to work with.

[Charlie]

If I had my way I think I would do Stainless on the water tanks, Aluminum on the fuel tanks, and poly for the waste tank. Here is my reasoning. I've tasted water from stainless and aluminum tanks. The stainless tastes better. Aluminum seems to be good for fuel tanks no logic to that one except to save $$$. I would buy a poly tank for the waste b/c they are not as suseptible to the caustic materials that they are used for. Another thing would be on the poly tanks I would use a standard size so that if I had to replace it it would be easy to do.

[Weyalan]

stainless, in my opinion, is worth the extra cost.

[DeepFrz]

Would the school (instructor) ensure that they meet all relevant guidelines and regulations?

If so then aluminum fuel tanks, stainless water tanks, and plastic waste tanks. Although a good filter will remove the taste from the water tank, so could be aluminum as well. Make sure you have pickup and return lines for polishing as well as for engine and generator (?). These should all be kept separate. Welding bosses in the clean-out hatches are great for attaching the pickup/return tubes.

Get the article "Diesel Fuel Tank Design: Materials, Maintenance and Connections" in the April 2007 PassageMaker Magazine.

Life expectancy of any tank has a lot to do with the way it is mounted and cared for. If the tank is mounted and cared for properly it will likely last the lifetime of the boat.

[Stranded Mariner]

I remember there were studies linking aluminium in drinking water to Alzheimer's disease. Don't know how much aluminium would dissolve when you use it for fresh water tanks. But I would not like to take the risk.
Stainless will be more expensive, but for me it would be worth it.

[Alan Wheeler]

I remember there were studies linking aluminium in drinking water to Alzheimer's disease.

Who ever did the studies, now say that it has no relevance. But SST could also be considered Toxic. Chromium is very toxic and no one has ever tested SST to see if we get Chromium from the alloy.

[Pblais]

Probably best not to drink water and avoid all manners of problems.

[Stranded Mariner]

Originally Posted by Pblais

Probably best not to drink water and avoid all manners of problems.

I can agree on that mate!

[Charlie]

Originally Posted by Pblais

Probably best not to drink water and avoid all manners of problems.

I agree and to misquote a song by Bobby Bare: "Forget the water there are carsogenics in it. Stick to Women, Whiskey and Sweet . . . Red . . . .Wine." And Boats

[DeepFrz]

Stick to Women, Whiskey and Sweet . . . Red . . . .Wine

Oh, oh, they are all mostly water!