Hi Seeker,

I just meant the low drag portion of the lift vs drag plot for the section.

The 6 digit series airfoil sections have pressure distributions that encourage laminar flow over a good portion of their surface at low angles of attack. Laminar flow reduces the skin friction so they have lower drag when it is present. It shows up as a "bucket" on the lift drag plot for the airfoil section.

This turns out to be not so important in the overall lift to drag ratio of a catamaran. I could not see the forest because there was a tree in the way.

-colin