Jim - the point at which the line is tangent to the curve is the max L/D speed. The minimum sink speed is at the bottom of the curve. The issue is: which one if the best glide speed? Some say it is the speed that gives the max time to stay aloft (which is min sink; max time to evaluate a landing spot and prepare for the event), others say the speed at which you glide the farthest (max L/D; max distance to hunt more landing spots?). Tomato, tamato maybe?