The surfer/spotter problem of Geometry is answered on page 290 of the Enhanced Teachers Guide for Geometry by Jacobs (ISBN: 0716756072). Since we no longer use this book, here are the two pages that solve the spotter problem.
Geometry: Surfer and the Spotter (PDF)
FYI – We now use a smaller version called “Solutions Manual: Answers to Exercises for Geometry” which leaves out some of the old classroom teacher materials, including the above Sufer and Spotter solutions, but is cheaper and smaller. The older, larger version is no longer in print.