I've seen many keels with the chord getting smaller towards the bottom, is there a reason for this? Is there a 'magic number' or formula to taper the chord at the bottom?
I'm making my Footy fin. It's .040 brass sheet with a strip of 1/16" ply on both sides, glued with Gorilla polyurethane glue & sealed with Polyurethane clear. It's really stiff for the thickness. I sanded the leading & trailing eldges to get a good & thin foil-shaped cross-section.