Well, you'd want enough hollow braid to tie a bowline around the dolphin striker and then go around both front pylons to the rear pylons. With regards to how much shock cord, I'm pretty sure you'd want slightly more than that inside, but unless someone else responds it might be easier just to trial-and-error it... have a buddy hold the end of the shock cord at the rear pylon and then see how far forward you can bring the righting line...