As can be seen in the photos, the stern post has a number of repairs that have been made to it over the last 80 years. The blue tape represents a minimalist approach to removing the propeller aperture, which cuts into the aft piece of the stern post by nearly 2/3, seriously compromising the strength of the stern.
The final choice was to cut off the stern post parallel to the rudder stock roughly 6″ in, from the horn timber at the top to the shoe at the bottom. The stern post will then be renewed.