How to tie a Sheepshank: Method 1
Make 3 turns that cross over themselves, all of them in the same direction
Put your hand through the back of the right hand turn and pull the centre turn through the right hand turn.
Put your hand through the left hand turn and pull the middle turn through the front of the left hand turn.
The rope that you pulled through either end now forms two loops. Pull these loops gently.
To tighten the knot and make sure it holds pull on the two 'standing parts'. That is pull on the two ends of the rope. Ensure that the knot is tight before use else it will slip.
How to tie a Sheepshank: Method 2
Arrange the rope into 3 equal 'lengths'. Often the two ends will be unavailable (e.g. they be secured at the ends to a tree) so you will have to loop the rope as shown. If you are using a sheepshank to relieve strain on a damaged portion of the rope make sure that the damaged portion is the middle piece of rope.
Take one end of the rope and form a crossing turn.
There is now a loop and a crossing turn at this end. Take the loop and push it through the crossing turn.
Pull the end of the rope ensuring that the knot is secure and tight. Note that there is no 'tying' a knot at the end.
Repeat for the other end of the knot. Make sure that the knot is tight before use else it will slip.