Let's get the ball rolling with square knots and half-hitches. When I was a lad, a mere tenderfoot, I was learning the lore of the Boy Scouts. I still have a lot of respect for them, even though I don't happen to agree with 100% of their ideas.
I remember the old story of a young Boy Scout who had just shown up at the scene of a crisis. A steeplejack was stranded high up on a tall chimney, and a crowd of 100 people stood around as he pleaded, "Does anybody know how to tie a square knot?" Apparently he had some ropes dangling down to the ground, and if any person knew how to tie a square knot, the steeplejack's life would be saved. If a "granny knot" or "false granny" were tied, he would probably fall to his death. And, nobody in the crowd was really confident about knowing how to tie a square knot.
This young scout had just passed all of the relevant tests. He spoke up with as clear, confident a voice as he could, and asked, "Where should I tie the knot?" After receiving the correct instructions from the guy on the chimney, the scout correctly tied the knot, and the steeplejack let himself down safely. The cheers of the crowd went to applaud the young Boy Scout. As we old scouts often say, "Shucks, Ma'am, 'twarn't nothin'..."
Tying knots used to be a standard set of tasks for young scouts. Making a display board of knots was, too. I never made a board to display all of the knots I knew. But I sure made a lot of knots. I still do today.
First of all, a square knot is much better than a granny knot, but I would never trust it for my life. A square knot with a half-hitch or two is much more reliable and trustworthy than a square knot alone. So, if a guy up on a chimney said I had to be sure to tie a square knot safely to save his life, I would request permission to put a couple of half-hitches on each side to be safe. See Figures A and A'. You should never make and use a granny knot, as shown in Figure X, as it's likely to either jam up or slip. But you should recognize it when you see one.
The square knot is similar to the familiar knot for shoelaces (not shown), which could properly be called a slip square knot because pulling on either one of the loose ends will untie it.
Similarly, a bowline, as shown in Figure B, is pretty good for making a loop at the end of a rope. But a bowline with a couple of half-hitches is better, and more trustworthy, per Figure B'. Note also that the slip half-hitch in Figure C isn't per se a good or trustworthy knot. But it can be used as part of a good knot, if you take good care of its loose loop and make it secure, as we will see later.
I have read that more people have died when a square knot slipped or failed than from using any other knot. So, a square knot with a couple of half-hitches is definitely trustworthy. Also, most knots have a tendency to get looser when you jiggle them. I tied some cords onto the door handle of my car using these knots, not tight, but just waving in the wind. After five months, the knots seem as good as ever. Coming up later: binding a bulky load onto a knapsack—or a truck.
All for now. / Comments invited!
RAP / Robert A. Pease / Engineer
Mail Stop D2597A
P.O. Box 58090
Santa Clara, CA 95052-8090