Fuel Tank Support?

[ericsil]

Nothing special to clamp my tank. I looked long and hard at the straps they sent and couldn't figure out how I could attach them so that they were going to help much. I just put a couple wooded bars across the top, wedged under the cleats, with some padding to avoid abrasion. Maybe with a secure shelf under the tank you could run tie down straps through the shelf and end up with a tie down that is more in line with the manufacturer's suggestions. That might avoid the sliding corner brackets altogether.

[Daddy]

Do those tanks swell at all. I know that my 18 gallon tank swelled so much one summer that it got wedged under the stern seat and I had a heck of a job getting it out. Could that swell and push up on the sole, just wondering??

[Cracker Larry]

Yes the plastic tanks do swell. If I remember correctly Moeller says you have to allow 5%, or something like that, in every direction. I don't remember the exact number.

[Matt Gent]

Kracor recommends 1/4" per foot in all directions: http://www.kracor.com/support/fueltanks.pdf

This is roughly 2%. I've seen 3% elsewhere.

[Uncle D]

Yea, Moeller says 3%.

[TRC886]

There was a big long discussion about this "recently". I believe this is the link I was thinking about, and there are several pages. I've linked part-way through the discussion, where the builder first specified that he had a poly tank. Previous pages show his coffin box and supports, later pages detail more specific mounting specifications. Hope this helps. BTW, be careful about taking TomW's advice It may/may not be accurate
http://forums.bateau2.com/viewtopic.php ... &start=230

[Joe H]

Thanks TRC, That's a good read, covers all the bases, I have about an 1" clearance on both sides and 1/ 1/2" on top under the sole.
I haven't done the math yet but I think I'll have enough room for expansion.

Joe H

[Daddy]

Some where I think I read about installing a tank by lightly foaming the corners (nothing on the sides). The foam will hold in in place and still allow for expansion. Might work. I am still unsure how you can vent the space in the coffin to get rid of the outgassing through the skin of the tank. I wonder how many tanks simply get installed and the space not vented?

edit: found this in the link above and it refers to pre conditiong the tank to expand it and then using foam to hold it in place

"That's interesting How about pre-conditioning the tank for 30-45 days, then mount it. FWIW, I put a tablespoon of expanding foam into each corner lock it in place. 2 years later and it's still locked I ran it by the Inca engineer before I did it though."

[KAndre]

D*** glad I'm a year or two from retirement and building an xf20 or gf18. Reading all this stuff on fuel tanks, gives me an corn field size head ache and says get a tank built after 1/2011 or EPA approved. Glad I don't have to deal with the ventilation of the tanks that TRC brought up and the pages after his link. Cl and Fitz must have gone through He** to get the proper ventilation. Glad I joined this forum. The info is great.

God bless, Keith

[Joe H]

D*** glad I'm a year or two from retirement and building an xf20 or gf18. Reading all this stuff on fuel tanks, gives me an corn field size head ache and says get a tank built after 1/2011 or EPA approved. Glad I don't have to deal with the ventilation of the tanks that TRC brought up and the pages after his link. Cl and Fitz must have gone through He** to get the proper ventilation. Glad I joined this forum. The info is great.

God bless, Keith

Welcome to Bateau Keith ,

This is a great site and top notch advise, I know exactly how I'm going to install my tank now and I know it will be done right with no worries.

Eric, Daddy, I'm going to go ahead and use foam supports on the corners, now I just need to find a local supplier of expandable foam.

Joe H