Line from keel to rudder

[davidsamuelson]

Hi,
I need some suggestions, please.
On an aluminium boat I want to put a line from the bottom of the keel back to the bottom of the rudder to prevent things catching in the prop. I do not want stainless since the hull is aluminium. What line is the best and how would I tension it? Should I put bottom paint on it? Is there already a tried and tested solution out there?
Any thoughts would be appreciated.
Thanks, David