Glass Tthickness Helo

[mattygreen86]

Hey guys. Started building my stand for my plywood tank this mornin, so now I've got all my materials and wood cut I know what my final dimensions are gonna be I was wondering if anyone could tell me what thsickness my glass needs to be. my tank is gonna be 72x36x34high. The glass will be 64x24. The bottom of the glass will be 4" from bottom of tank and top will be 28" from the bottom. Anyone know what thickness I'll need?
Secondly I'm gonna coat the tank with fibreglass Matt. Will I be able to silicone the seams inside before I fibreglass it or not or is there no point in doing that at all.

 

[BrianMcC]

id go with 10mm heavy but don't want it breaking!

 

[DrRob]

Hmmmm, interesting question. I've not made a ply tank yet, but I suspect that the glass calculators that we generally use don't apply (they're generally aimed at making sure that the surface area of the joint is large enough to handle the water pressure (hence the higher numbers for braceless). You can have huge surface areas so you need the glass itself to be structurally strong enough.
 
I'll have a ponder, but I'll be googling with the rest of them.

OK, found a calculator, can't promise it's reliability, but it does offer plywood options.
 
http/www.garf.org/tank/BuildTank.asp

 

[mattygreen86]

The garf calculator won't tell you anything over 48 long and 24 high

 

[DrRob]

Aye, noticed that after posting. Back to the drawing board.

 

[mattygreen86]

Any1 also know?