The first rib for the vertical fin is in progress. It consists of a plywood spar and strips made of poplar wood. I can only explain the choice of poplar wood by its weight advantage. So, I need to find a sawmill that stocks this type of wood, purchase it, cut it to size, and glue it on. The strips are glued on with excess on the outside, and then they will be milled together with the spar to match the rib profile. The milling of all the rib parts takes place on a self-built (!) computer-controlled router at a colleague's workshop. This way, the individual ribs are guaranteed to be perfectly accurate to the profile.