This was a challenging topic to research. One of the best sources was a caving and vertical rescue article that was recently pulled from the internet - bummer. Fortunately, I found another less comprehensive source: Article on Rope/Knot Strength. Let's take a closer look at our most common rescue knots:
- Figure Eight Family: Strength 80%. This is a climbers and rescue workers first choice due to strength, ease of tying, and easy to inspect. It is also a very versatile set of knots.
- Bowline: Strength 60%. If you use this knot, add a backing knot so it will not come undone. This knot is easy to tie one-handed. Once stressed, it can be difficult to untie. In general, we prefer the Figure Eight Loop instead. The Bowlinwe is no longer in the SWR Curriculum.
- Water Knot: Strength 64%. This is an exceptionally good know when working with webbing instead of rope. It is very easy to inspect. Make certain you leave plenty of tail, as much as 3".
- Tensionless Hitch: Strength 100%. Friction and a very gradual bend are the keys to this knot. It is also very easy to untie.
- Alpine/Butterfly: Strength 75%. A very effective knot for a 90 ° pull. When used to bypass a rope defect, strength is 57%.
- Round Turn with Two Half Hitches: Strength 75%. This is a self tightening knot and a far better choice than the clove hitch which can easily slip.
- Double Fisherman Knot: Strength 68%. We use the double (or tripple) fisherman knot to tie our Prussic Loops. This is a very smooth knot that doesn't slip. It is also one of the strongest knots for tying two ropes together.
- Prussic Hitch: Strength varies. Actually this knot is meant to be the weaker part of the system. The prussic Loop fails by slipping along the larger rope giving us a warning sign to back off immediately. This is an important safety feature in mechanical advantage systems.