The blocking in the centre of the rudder butts up against the front blocking and makes the top section solid and very strong.
This is also where the cheeks will be fitted, giving more strength to handle the torque from the tiller and the rudder itself.
The lower, rear area of the cheeks blocking is chamfered where the side panels will curve to the trailing edge, giving the necessary aerofoil profile.
This required a bit of thought and practice on some scrap ply to make a test piece. Here it is.
You can see how the profile changes from the front to the rear of the blocking.
A dry test assembly then followed, like this.
It all seemed to fit together as intended. Here is a closer look at how the test piece fitted.
Happy with this I then marked up the blocking on the edge-glued piece of Ash, as here.
Having cut it out I then scribed in the line for the chamfer, using one of the cheek pieces as a pattern. Like this.
The chamfer was made using the rotary sander and a P40 grit to grind the blocking to shape.
This is the finished piece in a test fit with the rest of the blocking.
So far, so good! Next step is final assembly.