The Bunny Ears variation of the Figure-of-8 knot has become very popular with many technicians as an anchor knot. It is particularly useful when attaching a single rope to two points in close proximity. Below is an image of the Bunny Ears knot.
This video shows one way to tie both the Figure-of-8-on-a-bight and the Bunny Ears variation:
Notice that the “common strand” shared between the two bights of the Bunny Ears (in blue in the image below) can be used to adjust the relative lengths of the bights prior to loading. Once loaded, the bights will lock.
Security of the bights
People often question the security of this knot and specifically question what will happen if one of the bights is cut. The concern is that the other bight may pull through the knot and result in compete failure. It would be an arduous task to test every possible dressing and scenario but we did conduct tests on the dressing shown above and found it to be very secure. The full report of these tests is available to RopeLab members here. In short, with the dressing shown, cutting a single bight should not result in failure of the other.
This video is typical of the tests and shows failure at the single Figure-of-8 at the other end of the system:
Rethreaded Bunny Ears
Tying the Bunny Ears as a rethreaded knot is actually far simpler than it sounds.
This technique allows direct tying into ring bolts and other structures without the need for carabiners. As a result, using the rethreaded Bunny Ears in these scenarios has the following advantages.
- Uses less equipment.
- Allows operators to get higher on the rope.
- Is more secure.
- Does not have potential for adverse loadings of connectors.
- Is less prone to interference by others.
In summary, the Bunny Ears Figure-of-8 is an excellent knot and is certainly worthy of consideration when anchoring ropes to multiple points.
© Richard Delaney, RopeLab, 2016