Rob:

You don't have to remove the rigging at all. On the TDR pulse you can easily
see the where the spreader touches to rod, you can run your hand up and down
the rod and see its location on the TDR. Since sound waves don't propagate
through cracks, the sound energy would be reflected back at the source and
the location of the crack could easily be identified.

All you need is a good piezo transducer that transmits and receives, a pulse
generator (a simple circuit) and some display like an oscilloscope. You can
even make a display on a laptop. With some signal processing you could
really do some great analysis of the rigging.

Think of a sonar with metal instead of water as the medium. One could even
spot cracks and corrosion in the end fittings. Also think of a musical
instrument. If the fret or neck on a guitar is damaged, it is easy to hear.
These same principals apply to the TDR.

Amen!

"Capt. Rob" wrote in message
oups.com...
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