Figure 8 as a stopper knot.

Figure 8 on a bight - for creating a secure loop on the end of a rope.

Clove Hitch - Good general that can be tied and untied quickly

Butterfly knot - An omni-directional loading knot. Useful for creating a loop anywhere in a line that can be loaded in any direction. Great for creating a 2:1 mechanical advantage in taking up slack in a line. It can take a little practice to tie, but once learned, a most useful knot.

Pete
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