The attachment of the vertical fin is completed.
The exact positioning was done by the help of a laser  beam before the holes were drilled. That’s 41 (fourty one!) holes that needed to be drilled and reamed. Unfortunateley my highly overpriced SnapOn drill failed half way through the job.

The construction is a true pice of engineering art.
The reason for the asymetric structure and the additional stiffening construction however remains misterious to me.

Now I look forward to see the rudder control cables run exactly through the provided holes.

Update 28. Oktober 2021: The control cables fit exactly through the holes.

The main bolts have a diameter of 16mm (!) and are made of CrMo steel.

The base of the stiffening construction is made of CrMo steel, the stiffener bars themselfs are of AL2024