The Multi Chine Proa
Additional thougths to the GD rig (Gibbins/Dierking)
The sail is fixed between top and end of the boom with additional 'camber control lines'. By changing the gap between the 'clew sledge' and the boom's end you can (before/after) sailing adjust the sail position along the boom - and therewith move the CE dependend from the total boom length.
To control the camber during sailing you pull the halyard (with fixed 'clew sledge') for bending the yard. See also the additional use of the camber control lines.
Building the P5
Sailing the P5