R-301 Untrimmed Length

The actual length (as delivered) of the edge of the R-301 x .016 rudder skin is 40 3/8", Van's callout on SK-7 is 40 7/8". All other dimensions called out on the "sketch" appear to match the skin. If you do the math - using the callouts as a "given" - the dimension in question is 40.323". This is so close to the delivered dimension I am wondering if the drawing is in error, some of the other dims are wrong or ?. Any enlightenment would be appreciated. OBTW - I have already built a -4 and and HR II, so I am familiar with the "adjustments" needed once in a while with Van's plans.

Thanks in advance for the advice!

I recall the same confusion doing mine. As I recall, the lower edge of the skin will just cover the lower full rib. It won't leave any material to attach the fiberglass tip. I inserted a 1 inch wide doubler between the skin and rib that gives a flange to rivet the fiberglass to.
Mike