Sooner or later your shock cord will probably get a little stretched. One of the most common is the paddle bungee. You can buy the materials, but not a replacement finished product, so here's how to rebuild it.
Hobie screw in fitting tool PN # 71115101 (recommended)
1/4" Shockcord PN # RS014BLK
1/2" Hog Ring PN # 21180000 (may be able to re-use your old one)
Shockcord End PN # 71115001 (should be able to re-use your old one)
In most of the Hobies the bungee is secured with a screw-in fitting called a "shockcord end" (top center in picture below). You can unscrew this using a "screw-in fitting tool" (middle, picture below).
1. Estimate how much you need to shorten the bungee, and then unscrew the fitting
2. Cut the old bungee out. Save the parts for now.
3. You should be able to re-use your old shockcord end. Thread a loop of strong string through the hole, loop it around about midway through your new bungee and pull it firmly through as shown below:
4. You may be able to re-use your old Hog Ring. Position it around the cord as shown to give you your desired length, then crimp with pliers. It's better to have your new bungee too short than too long, as you can stretch it but not shrink it!
5. Your finished product should look like this. Snip off any extra cord and carefully re-insert the new piece, taking care not to cross thread the plastic.
6. To replace your original pull tab, tie a loop of small cord (shown below is "550 parachute cord) on the bungee. You should be back in business with a nice snug fit:
Replacing a single bungee (not doubled over), it's much easier -- all you have to do is push it through your shockcord end and tie a simple overhand knot on the end. Here, you can re-use your original pull tab.