Need Some Righting Line Help

Hi all,
I'm trying to make a righting line to replace the worn out sagging one I have on my Hobie 16 which is 200 miles away at Lake Mead. It is the kind that loops around everything from one rudder to the other. I have 36 feet of hollow half inch for the line and about 28 feet of 5/16 shock cord. So the questions are these:
What is the length of the shock cord to put in the middle and how much 1/2 inch do I thread on to it with my trusty fid, so it pulls out to the right length? I'll leave about 3 ft. on each end. I would use my old one for this, but the shock cord has lost it's stretchy. I know, I know, I should have just bought a kit...

Thanks,
Jim

See my reply on the other forum, for whatever it's worth.

_________________
Warm regards,

Jim

Thanks, Jim.
I don't have the Hobie 16 here. It is 200 miles away at Lake Mead where I store it. The plan was to make a new righting line up and install it on the next trip. I thought someone might know the lengths from a kit or because they just made one. It would make it easier. I might have to go the trial and error method, but don't like cutting anything until I'm sure.

Jim Douglas