Finalizing the outline

Suffice it to say, there were many hours on Swaylock's, with Surfboard Design and Construction, and practicing with scrap 2x4s before starting to cut away on the rails.  Anyone who's built a board before (not me) would know to define exact end dimensions before placing the rails and before cutting the ribs - on a hollow wooden board, rib outline defines the board outline to a large exten. With the Grain method, they appear to define it almost entirely. With the stacked triangular strip rails, there's ~1" of wood that can be planed away so there's some leeway late in construction to modify board outline.  That's a blessing and a curse as there's temptation to modify the outline more than is wise.  Lesson learned: fix the target outline dimensions before building anything so rib dimensions and rail strip placement supports the exact outline.  
Here's how I finalized the board outline:
1) Snapped a chalk line to establish the center. Marked it every 1/2" for the first 3" from tail and nose; every 1" for the next 9"; and every 6" after that. All these marks will sand out but don't press too hard (or use a Sharpie).
2) Figured out the half width, i.e., distance from the center line to the edge to establish the exact outline of the board. This meant figuring out dimensions in 1/2" increments in board length for the first 3" of the tail and nose; 1" increments for the next 9"; and 6" increments through the rest of the board. I knew target dimensions for length, 12" from nose and tail, and max width. I needed to figure half widths for all the intervening intervals.  I found a similar board design in Surfboard Design and Construction (SD&C) which gave the half widths at multiple increments, but the SD&C board wasn't exactly the same nose and tail dimensions as my target. Since SD&C's nose and tail shapes were what I wanted, I normalized those measurements to mine, i.e., I wanted 14.5" for the tail (@12") so my half width was 7.25".  SD&C had a 7.58" half width for the tail (@12") so my dimension was 95.65% (7.25/7.58) smaller. I multiplied SD&C tail dimensions by 95.65% to get my half widths. I did the same with my target nose width and theirs.
3) With my Excel half width worksheet in hand, I marked  nose and tail outline points on the top deck using the digital calipers - this task alone made the $30 for the digital calibers seem like an incredibly good deal. Used a ruler to connect the dots.  Did the same all the way along the top deck, using the metal right angle lined up with the center line. I thought about doing this on butcher paper to get a half outline to lay on the centerline and trace, then flip to do the other side, but went direct instead. 
4) These lines were the board outline, i.e., the outer edge of the rails.  It was time to do lots of planing and do my best to hit the lines so that each side was exactly the same width from center to edge. My first tail outline was a rounded squash, but after planing, the way the rails flowed to the tail didn't look right, so I changed it to a rounded tail which was consistent with the SD&C design.

5) Once I planed to the lines and made sure each side was even, I discarded the half width dimension table and focused on feel - looking down the board, running my hand down the outline to plane out bumps and irregularities.

This pic on right is after all planing has been done to establish the board outline.  The rails are basically right angles to the decks at this point.

Next step, shaping the rails.