by Robert “SP” Parker
Over the last few years at courses and exams there has been considerable discussion over the use of the clove hitch in guiding situations. Reported, but unconfirmed, testing by the Department of Defense indicated that it was possible for the knot to slip at 700 to 1200 pounds of load and for sheath destruction and core damage to occur at 1200 to 1400 pounds. Consequently some guides felt that there was little point in having a secure, bombproof anchor if the attachment to it was the weakest point of the system. It was better to use an alternative knot in all circumstances.
To get more information the AMGA contacted Bluewater, who agreed to test the clove hitch. The tests were performed under the following conditions:
- An HMS style carabiner was used
- Test method Mil.Spec 191A was followed
- All rope was new and of Bluewater manufacture
- All hitches were tied so that the load was applied next to the spine of the carabiner
- A slow static pull was used rather than a dynamic load
When the knot was tied incorrectly, with the load strand farthest away from the spine of the carabiner, it was found that the knot tried to align itself with the spine at 250 lbs., and carabiner failure occurred–before rope breakage–at approximately 38% below the carabiner’s rated strength.
- Sheath melting is not a major problem. Even if the sheath were to be damaged, the core would probably tend to lie flat and grip the carabiner.
- Strength of the knot varies between 63% and 77% of the static breaking strength of new rope (compare this to 75%-80% for a figure eight and 60% for a bowline), with thinnest rope having the highest percentage. This is attributable to the greater difference between the size of the rope and the object around which it is tied.
at 1100 lbs
- The knot must be tightened down before use. A knot that isn’t will slip immediately, in which case sheath damage becomes a possibility. Slippage, however, depends upon a large number of factors, some of which include: the braid pattern of the sheath, the coating on the rope, the stiffness of the rope (i.e., a stiffer rope will slip more), the water content of the rope, and whether or not the rope is frozen. Additionally, a loose knot will have a greater tendency to distort and climb either the spine or gate side of the carabiner. Here the knot is extremely weak, with a great possibility of opening the gate accidently. This becomes more of a problem with a stiff rope or when a series of hitches are tied, such as when setting up a series anchor.
- Incorrect tying of the knot will result in substantial loss of carabiner strength. This fact is little appreciated by most users of the clove hitch. The UIAA recommends use of the Munter Hitch in the same configuration with load next to the spine to maintain carabiner strength, but the clove seems to have been ignored to date. Bill Griggers of Bluewater considers incorrectly tied clove hitches to be of far more concern than rope slippage or melting, and all users, professional and recreational, would be advised to note this and to tie the knot correctly. Incorrectly tied, carabiner failure becomes a real possibility.
So where does this leave us?
The clove is a useful knot that has limitations, but so do many of the techniques and equipment that we use in climbing and guiding. It is not substantially weaker than other commonly used knots, but extra care must be applied to its use. It must be tightened down, and it must be oriented with the load on the correct side. It is up to the discretion of each guide to assess these results and decide if s/he can use the knot correctly in the field. And clients should be instructed in its use and limitations, rather than believing it to be a knot for all situations.