Luiz,

Selftacking jibs try early 1800 on traditional Dutch working sail boats. The originals that gave the US scow its name. But I bet it is even older than that. Any these used a curve steel bar over which a large ring could slide. On the ring was a large block that lead the jibsheet that came from the bow to the clew. In practice it is identical to the system now used on cats.

Wouter