Here is a pattern correction. You need to make a 5th border to add to the bottom of the quilt (to get to 79” in length). Your quilt will be square if this last border set is not added. Step 7, a and d should read:
Step 7 – Borders Use remaining strips and letters to make 5 border sets.
a. Layout strips around the edges of the quilt, auditioning for color. I chose to put white at the top, med down the left side, dark down the right side and the bottom. Pretty much like the block and adding a 5th dark set to the bottom. Place the letters of the word Sea in different places in the border to see where it reads best to you, vertical, horizontal…
d. Sew the side borders to the quilt top – sewing from centers out. Press seams out and repeat for the top and bottom borders. Add the 5th dark strip set to the bottom of the quilt and press seams out.