Why is there a bungee running thru micro blocks inside the front beam on the Nacra I20?

Could be to keep tension on the front trapeze-wire set.

At the end of each of those lines, you cat attach a sister-clip. On the bitter ends of your sheets (downhaul, rotation) you add the other clips. By attaching the clips together, you can have the ends of the sheets tucked into the front beam. Keeps the tramp clean and neat, no tangles. Be sure and get a preventer line for when you trailer, so as not to lose the bungee inside the beam.

Have fun!

It's for the secret missle launching system that Nacra offered as an option on the big-powerful-fast 20 foot boats (read: not for f18). Pull up next to your competitor, flip the switch, and a rocket with a chum payload ejects onto their boat, causing much destruction and smell. It is very effective, and I plan to have my beams loaded for tybee this year.

Inter Michael got it pretty well described. Dont do what I did in ignorance which was to undo one of the tied off elastics (tied off because not in use), and then promptly let it go to watch it hurtle into the front beam not to be seen again. At this point you find the downloadable Inter 20 manual is useless! Then you have to find someone who knows how to reconstruct the system to come over and help you fix it. You can either use the system to stow any loose line from the main downhaul system, or the mast rotator control system. Perhaps it could do both at the same time if you were clever with lengths of line?
Regards
Chris

Trey, I can't wait to see the video!

Video? That's called evidence...and we can't have any of that!