"Stephen L. Cain" wrote in message
om...
"Tim Carter" wrote in message
.. .
"Peter Charles" wrote in message
...
On Sun, 13 Jun 2004 20:02:52 -0600, Willi wrote:



I know, but think a bit about what sort of fish can bend open a
heavy
guage, 2/0 sal****er, stainless steel hook, even if it is a Mustad.
My tippet was 14.75 lb. test Daiichi fluoro btw.


A FINE fish, I'm sure. But that hook bent before a 15lb tippet broke.
I
would expect a salt hook that size to be stronger than that, but then
I
know **** about salt water.

Willi


Leverage probably, plus the better tippet usually tests out a fair bit
stronger than their ratings.

Does anyone know of any studies done on the effects of tying a fly on a
hook? I generally try to hold my hook as I'm winding anything around
it,
especially when I'm wrapping tightly with thread. It seems to me that
the
hook undergoes quick and repeated bending while I'm tying; very similar
as
to what I do when I want to break off wire ribbing. I assume each brand
uses a different alloy and that each might be affected by that
particular
type of stress (I can't remember/find what it's called).

Fatigue.

Usually fatigue damage is followed by fracture, rather than yelding:
the hook would have cracked rather than straightened. If you get a
magnifying glass and look at the broken end of your ribbing, you'll
see a slight necking (decrease in diameter) and a jagged fracture.

Interesting. If a hook experiences fatigue, but only half as much as
required to cause complete fracture, wouldn't the metal would be weakened
and be more susceptible to bending??


If you get more interested, the phenomenon of failure from cyclic
variable-amplitude loading and cycles-to-failure is called the
Palmgren-Miner Rule.

Steve