Cracks would
raise the impedance. The cracks could be located along the length of
the rod
by simply applying the pulse signal at one point.

Seems to me that for this to work well you'd need to remove the rod
from the boat and tension it is some sort of way, equally. Then you
might read cracks, but be unable to actually locate them, meaning a
small non-dangerous imperfection in the rod might give a false reading.
Seems like a tool that would get abused to sell a lot of uneeded
rigging..
Just about every rig failure I've ever heard of was wire. While I'm
sure rod has failed....I've never heard of it. Anyone know of a rod
rigging failure they can point to online? I'm too sleepy to google
today.

RB
35s5
NY