FBI system 1 jib (plus mast, stays and spreaders)

The jib has a wire luff that joins a wire halyard, connected to the muscle box. The purchase in the box comes out on the low side and cleats off on the centre case. Muscle boxes were common a few decades ago. A more modern system would have two blocks of three sheaves beside the centre case with a single cascade by the mast to give 12:1. I am sticking with the box.

The side stays have adjusters at the base, and the spreader position is also adjustable. These alter mast rake and bend. Spreader position can't be altered on the water. It is possible to alter the stays between races, with the right setup, but we won't be doing that.
The jib sheets go to adjustable tracks to control slot depth.
The jib track, adjustable without moving forward

Work so far includes repairing the muscle box that is used for tensioning the jib halyard. This is an eight part purchase housed inside an aluminum section. The muscle box was jammed when I brought it.

Jib systems diagram


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