I am a first-time builder, Shearwater 17, and am ready to start the beveling, but I don't feel like I fully understand it yet.

Here is a very basic question that would help a lot.  The idea is to shave off the inner corners, so that the outer corners of the two abutting planks of plywood can more-or-less meet, and there is less of a visible gap on the exterior of the hull/deck between the planks. Also, the butt-ends of the plank would face each other better, and not just meet on the point of the corners. 

Is that correct? 

Also, the angle that is listed in the manual - which angle is it?  The outer face/edge of the panel?  The inner face/edge of the panel?  Or something else.

Thanks for any help or guidance.  A good diagram would be worth gold!!

Alec