On Friday, August 18, 2017 at 6:44:09 PM UTC-4, Terrance D McCarty wrote:
I am building a stand for one of my rain barrels, (full capacity 50 gallons,
or ~ 420 lbs).
I am using 3/4 inch plywood, and plan on supporting it every 60 degrees of
circumference with 2 x 4's with 2 or 4 in the middle of the circle.
Think this will hold 420 lbs.of water, plus 25 lbs of barrel weight? (Total=
~455 lbs)
Thank you.


You need to use the Sagulator.

It will calculate the sag of more species of wood than I knew existed based on
total load, load distribution, support method and a few more factors.

http://www.woodbin.com/calcs/sagulator/