F28R Daggerboard specs

I damaged my Corsair F28R daggerboard sailing in Mexico in the Spring. Because replacements are pricey, am planning to repair it. Had a neat plan and was about to put it into action when I determined that I wasn't sure what the original foil shape was. The foil is similar to a NACA 10 foil but since it is swept back, and I presume the "foil" needed to be perpendicular to the water surface. I was able to simulate both sections in my Cad-Cam program.
Anyway I took a number of measures and found that it wasn't a NACA 10 as the leading part of the foil was narrower than expected and this wasn't corrected when I rotated back 10 degrees.
I know this foil provides some lift because I had to keep it retracted during my trip home and found I had a lee helm. This boat sails in the 0-25 kt range.
What I don't know is: Do foil lift shapes change when placed in water (that is, would a slimmer entry be desirable in water compared to in air?) I wouldn't think so but ...
Does anyone know what the design specs for the foil shape were for this daggerboard? I have twice written to Corsair Vietnam and have been unable to get this information.

 

Generally speaking, foils perform the same in air, water, or any other fluid, as long as comparisons are made at equal Reynolds numbers.

The NACA 4-digit shapes are decent all-around performers, so you wouldn't go too-far wrong using the NACA 0010.

 

Thanks for your response. Helpful. I found Paul Zander had posted an article on Centerboards and rudders in 2010. Apparently, the correct NACA0010 shape would improve performance at wider angles of attack. I also learned he was experimenting with an parallel sided foil which moved the AOA back farther. But found n0thing on foils with a narrower than normal front of the wing config.
Re Air vs Water there are two differences. 1. cavitation, which as near as I could tell is not important unless you achieve 50 kt, and 2. separation which may primarily be a very slow movement hazard. I will say that at speed (15-20Kt), I sometimes loose rudder attachment.
The F28R is a rather unusual boat and I have learned to be very cautious about modifications.

 

Seeing as you are already looking at your foil's ; re the rudder problem.
is it the foil shape, wrong position on the boat, not enough leading edge, etc, etc, ?
curious ....

 

My concern is the shape of the foil. When comparing to standard NACA foils, it measures as a NACA 0010 foil, but the leading edge is narrower than the true foil shape by about 1/4 inch. The leading edge of a foil can be modeled by a series of overlapping circles, and the radius of these is quite a bit smaller than expected. Looking at pressure diagrams this suggest that the foil is underperforming at a number of angles. Not sure if it creates or reduces friction in a marine foil.