Display Mesh query

Hello All,

I am drawing up a blank core for a kayak rudder that I will 3d print and then cover in carbon/epoxy.

The surface is shite in that it is a 2 rail sweep (I am writing you a long letter because I don’t have time to write you a short one). The points look Ok, but it shows this on surface analysis:

I am assuming the defect is only in the display meshes and is not there in actual fact.

Am I correct?

If not, can this surface be corrected, or do I need to go back and study James Carruthers’ tutorials again?

Kind regards,

Hugo.
Boat Rudder.3dm (769.1 KB)