In answer to all the questions I've gotten in my private email,
a stress curve basically tells you how a rod will bend when
a load (the line) is applied. The tip of the rod is on the left,
the handle is on the right of the x axis. The higher the stress
(up the y axis), the more the rod is bending.

The values drop off drastically at the tip because as the lever
arm approaches zero (the tip top) there is less and less for the
line to exert any force on. This is reflected in real life. Hold a 
rod steady and pull the line 90 degrees to the rod. Look at the 
last few inches of the tip. If you don't believe its more or less
straight, hold a ruler up to it.

Garrison was basically reverse calculating from a stress curve
to get diameters. His stress curves do not show true stress
values. What he was doing was taking what he believed to be
stress values for a "progressive" bend in bamboo, and trying to 
calculate diameters from the stress value. Garrison's stress
curve will not look like a stress curve calculated from true 
diameter measurements.

There is no tensional force on a fly rod. The only way you will
get tensional force is to tie the line to the tip top. All the forces
in casting are angular or compressional.

Darryl Hayashida

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