control block understanding

[Nocalsolo@xxxxxxx]

To anyone,

My control blocks are the right size
and exactly the 23 degree bevel
But don't look anything like the photo which looks more pyramid like. 45 
degrees would be more like it.

It is placed along side the centerboard trunk. What goes on it? What does it 
do? Can't tell from the manual.

Thanks 
Ken (#28)