Makes sense - it's the ratio of two similar triangles:
View attachment 554590
WL/D = CD/H
The "Triangles" will always be the same when W = H
(Width definition: Back of tree to back of undercut) Its always a 1 to 1 ratio
As long as lift is greater than offset displacement at a 1 to 1 ratio it will pass COG. Providing it's not branch heavy to the back side. Marshy worked out that exact example; 12" back cut to pivot + 1" lift and it was just under 5°. That could prove to be helpful for me considering I can use my 5° ; 10" K & H wedges by holding the bottom of the wedges and straight arming them in front of me with the inside plumb and one eye closed standing on one foot chewing Wrigely's Spearmint Gum; I can convert my 1 to 1 ratios to degrees based off of now knowing a 12" back cut to undercut at a 1" WL = 5° offset.
At a 6" wedging point to pivot, (sideways wedging) the degrees doubles to 10° and 2ft undercut to pivot would be 2.5 °.
1" lift will correct them all to either plump or horizontal.
Or if they were all 5° then the '2ft backcut' would take a 2" lift and at a 6" wedging point a 1/2" would accomplish the same.
Judgment on Branch offset weight/weight of species, wind AND additional top sag 'if you created the lean ( eg. tall,small diameter sets back) VS angle and wedging point distance in conjunction with tecneque, wedges and axe
Is all relevant to experience.
Today's fun problem:
If it took Buckin' Billy a 2.4 " wedge lift to fell the tree. The back of tree to pivot was 2ft,
Based on a 12" back cut to pivot with a 1" WL = 5°
How many hits did it take Billy. .
Srry no that's not it...lol
How many degrees was the back lean he would have had to overcome?