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 07-16-2010, 08:52 #30 tjm Senior Member   Join Date: Sep 2008 Location: Auburn, MA Hammock: JRB BMB Tarp: JRB 11'x10' Insulation: JRB TQ / UQ set Suspension: JRB tri-glide Posts: 411 a little math All other things being equal, using 6x6 posts rather than 4x4 posts will make the posts "6 times more resistant to bending due to lateral loads [i.e. the hammock]" Deflection of post at location of hammock connection d = ( f * h * h * h ) / (3 * E * I) d = deflection of post at connection of suspension f = lateral force on post from suspension h = height of connection of suspension E = modulus of elasticity I = moment of inertia Moment of inertia for rectangular cross section I = d * b * b * b / 12 I for 4x4 post = 12.5 inches4 I for 6x6 post = 76.3 inches4 76.3 / 12.5 = 6.1 These equations also shows that A - using a material with a higher modulus of elasticity, E, than wood would allow for a small cross section [say a metal fence post] B - the lower to the ground you hang the lesser the bending moment Good luck. Last edited by tjm; 07-16-2010 at 09:03..