This is a cache that I have wanted to do for a long time, I did one similar in Minnesota where you had to identify parts of statues.
What you need to do go to the following coordinates and identify which knot you find there, take the number of the knot and replace the letter. You do not need to find them in any order. I have also include the location of the knots that are not used. (USE THE LATEST IMAGE OF KNOTS IN GALLERY)
Final location N 41,E(A+B).GFA - W 112,EB.DGC
All of the knots are in the confines of the Freeport Center. The Freeport Center is a manufacturing, warehousing, and distribution center located in Clearfield, Utah, United States. It was originally built in 1942 as the Clearfield Naval Supply Depot, which was decommissioned in 1962.
Thanks to del2u and dix1 for validating this cache, they get the FTF.