Chances are you have heard of the humble Granny knot! It's a
general-purpose knot which is useful for tying two ends of a line
together. I suppose grannies from many generations have used it for
tying up a parcel with string...
As a child, the Granny is one of the first knots you learn. I can certainly remember using it with coarse twine or string.
And yet, this knot does not do a great job of fastening 2 lines together. Try it - and see how the knot tends to slip through when you apply a lot of strain.
Despite being a bad choice for fixing your flying line (!), the Granny Knot does come in handy in less demanding kiting applications.Now, if you really want to go overboard with knot-tying...
Back to the Granny...
For my kite designs, I mainly use this knot for tying a completed keel to its vertical spar. The 2 lines already have a Simple Knot tied in next to the keel's edge, so the Granny pulls the edge tightly against the vertical spar, but does not distort the keel edge.
In this situation, fixing the knots with glue is a good idea, so the keel can't shift along the vertical spar. Of course, you need to use enough glue so it contacts the spar as well as the knot itself. As a side benefit, the Granny can't come loose either.
In a keel, the flight load is shared among several lines, so a fancier stronger knot is not required. Well, I've never had one let go yet! When I say 'stronger' here I mean 'less likely to weaken the line'.
The first half of this knot is also handy for attaching
shoe-lace ties to dowel. By not completing the knot, there is less of a
bump to interfere with the other dowel when it is laid across and
secured. A drop of glue ensures that nothing shifts.