Center board Bungee

I haven't had any luck getting answers here before, but I'll try again. My new to me 1984 14.2 has a double braid line from the centerboard to an eye on the transom to keep the board down. I'm sure this should be a bungee to give shock absorption in case of impact with something. What size bungee is used and how far is it stretched for proper tension?
I used a loop of 3/8" or 7/16" bungee. I ran it through the loop on the top of the CB and a shackle. I played with the tension until the board stayed down under normal sailing conditions. I started by measuring the distance from the top back of the CB to the loop on the stern, doubling it, and then subtracting a couple of feet. I suggest starting a little too long and finding what works.
Best of luck, Karl
I believe the instruction manual for the 14.2 has a diagram that shows the factory length (not sure if it gives the diameter but it may). I think the manual is shown on this site.
It would be easy to make, but if you want the easy route (as I chose) you can order from Catalina Direct. I Figured I'd make my next one!