My understanding is that upwind drive comes off of the front fins more than the rear. That is why race boards have two in front, one in back. The other factor is that they are more vertical, with less sweep, and are nearly perpendicular to the board -- at least relative to the "carve" fins.
So, if the wind isn't too light, your weight is balanced well, the board is flat, and you are still not going upwind, then try the front pair of fins from the quad set or the three (race) set. I bet you could still use the carve center rear with the front quad pair. Might make turns just dumb though.
- Droffats
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