a Gab..

Already during dry fitting of the main deck I discovered an gab between the main deck and the first frame which was impossible for me to fix at the time.

Now after gluing the main deck into place I decided to bridge this gab with an extra plank and a piece of cardboard to simulate caulking

Even knowing that it will not be visible later on, I decided to glue cardboard on the other side of this extra plank as well before planking the front.