Look up. If you are reaching or running and a portion of the sail is beyond perpendicular to your course you are spilling air and need a vang.
Keep it simple.
Charlie P. Mud Hen 17 #69 Mad Hatter
To travel hopefully is a better thing than to arrive - R.L. Stevenson
I suspect that, if you should go to the end of the world, you would find somebody there going farther . . . - H.D. Thoreau