Thursday, March 19, 2015

Knots - Figure-eight

Regular Figure-eight

The figure eight knot is a foundation knot that is useful in many situations. In its primary form it is simply a stopper knot. IE, a knot that creates a stopping point in the rope when it is travelling through a hole of some sort. 

In sailing, a figure-eight is often used at the end of a line (for example a jib sheet) to keep it from escaping through its block (pulley). It is used similarly in rock climbing.

While many knots are known to cause a degradation in the strength of the rope that it is tied in, the figure-eight fairs pretty well in this respect. It causes a reduction of 20% from the original breaking strength.

Tying the knot

Animated figure-eight
Animated Figure-Eight
  1. Make a "loop" by crossing the working end over the standing end
  2. Continue the working end around the standing end a full turn to make an "elbow"
  3. Bring the working end back up through the loop
  4. Tighten as needed

"Figure-eight on a bight"

The figure-eight on a bight is used any time that you need a strong loop tied in a rope and it doesn't need to be adjusted regularly. The figure-eight on a bight is strong and easy to tie.


Tying the knot

Use the exact same technique as above. However, before you start, double the rope back on itself to create a loop. Treat the loop as if it was a single rope and tie the figure-eight as you did before. You will be left with a loop in the end.

"Figure-eight follow through"

The "figure-eight follow through" is a form of the figure-eight that is often used in rock climbing as a way to tie into the the harness since it is:
  • Easy to tie
  • Easy to verify that it is tied correctly
  • Doesn't reduce the strength of the rope considerably
  • Doesn't slip
Once tied it is identical to a "figure-eight on a bight" (above) but is tied differently because it is often used around a closed object (like the anchor ring on a harness)

Tying the knot

  1. Start with a figure-eight tied at least 30cm up the working end of the rope
  2. Bring your working end around whatever object the rope needs to be fastened to
  3. Feed the working end back into the top of the figure-eight
  4. Follow the exact same path backwards through the knot. Make sure that you keep the working end tightly following the existing knot path. 
  5. Exit the knot through the standing end side of the knot
  6. Tighten
  7. Lock with half hitches, if required
Animated Figure-eight follow through
Animated Figure-eight follow through

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