Last season I purchased an 18' solar cover, which was a square so it had to be cut to become round. I, the scholar, decided to fold the cover up and trace 1/2 a circle and cut it out to open into a round circle.

Well I did not plan this very well as I had two 1/2 circles after I was done.

After being frustrated, I realized that this was a good idea. It makes it a lot easier to put on and off.