What size rigs are you using?
If you use the same size in the front that's on the back, and the front sailor does not "undersheet" a bit (keeping the front sail opened up a little more) the Gemini is a little hard to get headed really high and fast upwind as the front rig tends to drag the nose off the wind.
If you use a smaller rig (1-2 m2 is a good number) on the front, then the front rig acts more like a jib on a sloop rigged sail boat, if the front sailor watches the "slot" between the sails.
Often the front sailor will want to sheet in more a close the slot, but that shuts off a lot of drive from the rear (larger) rig.
When fully planing, and with a good balance between the front and rear rigs, the Gemini can be sailed upwind "on the fin' just like a giant shortboard.
When sub planing, put the center board down and "rail" the board to leeward and run upwind on the lift from the centerboard.
Until you have mastered sailing upwind on the fin (fully planing) you can always have both sailors step slightly off center on the upwind side to roll the board slightly upwind rail down and the Gemini will charge upwind on the rocker line.
Hope this helps,
Last edited by Roger; 17th August 2007 at 09:48 AM.