Thanks everyone. I think my past failures were from the rope being to thin.Will pick up some thicker rope.
There's some short footage in this vintage video (Potter's of Japan, Party II by Richard Peeler) which shows how Shimaoka used rope to impress a decoration in his pottery. You can skip to 10:00 to see it. Notice the ropes below the paddles. They are fairly thin in diameter and are used by rolling across the pot.