Jib Car
From MITNA
The jib car, or jib lead, is a block that is mounted on a track on the deck of a sailboat. This block can be moved forward or aft along the track. This changes the angle that the jib sheet makes with the clew of the jib sail. By changing the angle of the sheet, you can adjust the amount of tension on the foot or the leech of the jib sail, which adjusts its draft and twist.
