Søren Andresen (DEN) uses this interesting arm winch setup on his boat.
The idea is that by attaching the jib and mainsheet at different points wrt. the block on the arm you can get unequal travel on the sheets. As shown here the mainsail can be adjusted virtually independently of the jib sheet when close hauled.
A number of people were interested in it at the Euros in Arcos so Søren has made a detailed drawing and kindly allowed me to publish it