Problem with the non-steel rigger lines is they don't work with the positive ion control on my Canon Mag 10s nor would it work with a Black Box. But non metal line would surely kill it.
Don't know about vibration damping, but you might make the rigger's "harp string" artificially too long to "sing" if you attached a metal wire with an alligator clip to the rigger wire, perhaps clamping the other end to a metal surface on the boat. Just a thought if anyone cares to try.
Pancake weight or more weight will help depends on speed. I have big jons when the noise gets to me I have small bungee cords I wrap around the boom, then both hooks on the cables adding a little tension. Ball still goes up & down no problem. Works OK. w-fat
