Go up to Lowe's, Home Despot, wherever, and purchase any of the following that you don't have on hand:

1) About 20'-30' of rope
2) A 3-4' long 1/2" wooden dowel
3) A plumb bob
4) Some kite string
5) A 1/4-20 bolt about 3" long, and a 1/4-20 blind nut
6) A 1x2 board.
7) A small string level
8) A pulley
9) A hook


Then, [link=http://home.mindspring.com/~the-plumber/Vanessa%20CG%20Machine.htm]use all this stuff to build a Vanessa CG Machine[/link].

It's simple, elegant, inexpensive, and will determine the CG AND the impact of any amount of weight added anywhere on the plane for ANY airplane. About a month ago, just to prove it was possible, I balanced a < 4oz foamy on it, and JUST YESTERDAY balanced a GP Ultimate 1.60...and you better believe I'll be balancing the 102" Edge on it soon.