Tony,

I'm no expert but it seems that your sail was too full for the light winds. Did you feel like you were heeling over rather than accelerating on the upwind legs ?

It would be a good idea to play with the sail shape on the beach before you set out. Adjust downhaul, mainsheet tension, outhaul and mast rotation for the upwind closehauled setting. Each sailmaker has their own designs so it's hard to say what works best for your sail.

Get Darryn to have a look at the sail shape and mark some positions on the mast, boom, mast rotation and mainsheet for reference. It will only be an indicator due to it being a static measurement with no boat speed and minimal wind force on the sail but it will put you somewhere in the ballpark to begin with.

Regards,

Peter