One other comment. I do remember another article in Soaring about
making tow ropes. I can visualize the pictures in the article; he
used a hand made copper fid, puts the tow rope through some black
tubing, and used electrical tape at the business end. But I cannot
find the article in the archives. I searched for "tow rope" without
luck. I think the search engine may be not quite right because
putting in "water knot" got zero hits. Hmmmm.