My book has Poco Barta inch measurements in fractions. Yes, you are correct, it is shown as 11 12/16.
Also, the 34" coaming offsets are found in the Curlew section.
Each bracket A dimension should be 4"+ the keel stringer Z dimension.
I ended up not using the bow & stern assemblies shown in the photo. They're built as designed, assembled with Titebond III and painted with 2 part grey polyurethane. You can have them for the cost of shipping.
I changed direction with my kayak and had custom laser-cut pieces fabricated.
There are several other Poco Barta related posts in this forum, some misspelled.