>>475237Your sheep shank is best tied with pic related or climbing rope. The key is that the rope has to conduct friction against its self or else it will fall apart. I remember the first time I tied it and it kept slipping apart with synthetic rope. It's kind of a gimmick because to keep the knot together requires constant tension. So if you were in a situation that you needed to shorten your rope and didn't want to cut it and it was for holding up a tarp? I dunno.
Most important knots I can think of are:
Square knot (joining knot for joining rope of equal size)
Two half hitches (for loops that need to be tight)
Taut line hitch (For loops that need to hold lines tight)
Bowline (For loops that need to stay put, can be tied one handed "rescue knot")
Clove hitch (for starting lashings, tying around logs/large sticks)
These are the top 5 I use. Also useful:
Timber hitch (for wrapping around logs)
Figure 8 (follow through)
Sheetbend (for joining rope of unequal size)
I used to know more, but it's been years since I got out of scouts.