Garrison invented an own simplified calculation method for taper
calculations. Consequently the parameters he used in his
calculations where fictive. In fact the stress curves that he used
didn't reflect reality. His method however was well suited for his
purpose. By adjusting his parameters, testing and building flyrods,
Garrison finally produced excellent rods. Should a more
sophisticated method of calculation come into use, there are such
methods available today, adjusting the parameters would still be
called upon in order to end up with the desired character of the
final rod. Therefore the following reasoning is based on Garrisons
method since it is simple and practical.
Casting length is one of the variables that have to be
established before the taper calculation can take place. Casting
length is therefore a personal matter to be faced as well as the
type and class of line that the rod will be calculated for. See more
about this further down.
The "Tip Impact" that Garrison used, and which he defined
himself, is the product of the weight of the line (plus the weight
of the tip guide) and a dynamic factor. But once the rod bends,
which it will in reality, the theory that Garrison used becomes
false. In fact I am just saying that Garrison adjusted his
calculation method to suit the type of rods he aimed for. However,
his method provided a comfortable and consistent way to calculate
tapers for different lines and casting length. Personally I like
this kind of "engineering". See the page on "Theory in Brief" below.
Rod action or the character of the finally flyrod is entirely
determined by the choice of stress curve. Herein lays the secret in
Garrison's theory. Or the Art. The rest is pure matemathics.
Some trivial basics about definitions in mechanics and stress
analysis for those interested are to be found here: About stiffness,
bending inertia, bending moment, bending stiffness and bending
stresses, neutral layer etc.
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