Sheepshank is a type of knot.
Canonical Name: sheepshank.
Variant Name(s): None.
Category: bend.
Origin: Ancient.
Related knots:
Releasing: Non-jamming. Holds shape under tension but may fall apart if the tension is removed.
Efficiency: 46%.
Caveat: spills if not under tension from both ends.
Uses: The main uses of the knot are (in decreasing order of usefulness):
- secure a load in a way that can be easily undone when no longer needed, but provides a block and tackle mechanism allowing a load to be secured much more tightly than is otherwise possible.
- shorten a rope (though there are better ways to do this)
- bypass a section of frayed rope - useful in poor economies where rope is expensive
Comments:
Structure:
Tying:
The knot is constructed as follows:
- pull a section of rope back and lay it alongside the rope, so that the rope forms a Z approximately 20 cm long.
- flatten the Z so that there are 3 sections of rope lying alongside each other, with two U-bends where the rope reverses direction.
- at each U-bend, grasp the U-bend in one hand, thus holding two of the rope sections. With the other hand form a small loop in the remaining section and draw it over the U-bend so that the loop forms a half hitch and stays there if the free end of the rope is pulled taut.
- repeat at the other U-bend.
This knot is extremely useful for tying loads down such as on a trailer or truck. The knot has two features which make it invaluable here:
- it provides two loops, one at each end of the knot which can be used to pass a rope through.
- the knot remains secure under tension, the coarser the rope the more secure it is
- the knot falls apart easily when tension is removed.
Typical use in tying down a load on a truck is:
- start with one end of the rope tied in a clove hitch around a rail. If the rope is reasonably coarse and this clove hitch is held under tension then it will remain secure.
- pass the rope over the load, around a rail on the other side of the truck and back over the load to near the original clove hitch
- pull the rope reasonably taut and then form a sheepshank about one metre from a rail on the side of the truck.
- pass the free end of the rope around the rail on the side, then back through the loop on the sheepshank nearest the rail, then back to the rail.
- pull hard on the free end of the rope to tighten it. The structure of the knot provides a leveraging effect like a block and tackle, so that considerable tension can be brought to bear to secure the load.
- when the tension is sufficient to secure the load but not damage it, pass the rope around the rail and tie it in a series of half hitches. If the rope is likely to bind and be difficult to untie then use a loop of the free end, so that each half hitch can be undone by pulling on the free end of the loop.
- clove hitch
- sheepshank
- half hitch