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Why Knot?

Thursday, December 1, 2016

Why Knot?By Pat Furr, Safety Officer & VPP Coordinator for Roco Rescue, Inc.

As rescuers, we all have our favorite knots and our favorite ways of tying them. Depending on the application, there may be several knots to choose from that will perform slightly differently in terms of efficiency or knot strength. You can go online and order any number of books ranging from a couple of pages thick to 2’ thick with hundreds of knots in it. The trick is to decide what applications you will need to perform with your ropes and knots. If you don’t need to shorten a rope, then you don’t need to know how to tie a sheepshank. Or, if you use manufactured harnesses, then a tied Swiss Seat is not a needed skill in your inventory.


For the most part, we can break applications into 6 categories for rescue purposes: 

1) Knots that form a permanent loop in the end of a rope (Ex. Figure-8 on-a-bight)
2) Knots to tie around objects (Ex. Bowline)
3) Knots to join ropes together (Ex. Square Knot)
4) Knots tied in the middle of ropes (Ex. Butterfly)
5) Hitches binding and adjustable (Ex. Prusik Wrap or Clove)
6) Utility knots (Ex. Daisy Chain)

Why Knot?Whenever we tie a knot in a line we lose some of the efficiency in the rope or webbing we are using. Generally, the more acute the first bend in the knot, the more efficiency is lost.

Other factors such as angle deflection, direction of pull, and rope construction all have effects on a knot’s efficiency. Then, there’s the type of load the knot will see (two directions or three directions). The direction and critical angle applied forces may change the efficiency rating of a knot greatly. In rescue, we try to use knots with fairly small efficiency losses, generally between 18-37%.

There are some other considerations beyond knot strength when choosing which knot to use for any particular application.

Ease of Tying

Why Knot?

In addition to knot efficiency (strength), we also must think about many other things such as ease of tying especially in those hard to access places where you wish you had more Gumby genes. Where and under what circumstances will you need to be tying the knot? Will it need to be tied one-handed? Is speed a consideration? Take a calf roper, for example, he needs a knot he can tie quickly and securely. Would you be able to tie a Prusik on line for self-rescue with one hand if the other is stuck in the device? What about an emergency situation where you might need to bail out a window while blinded by smoke?

Say you want to clip into a fixed rope but need to do it one-handed? The Clove Hitch will be much easier to tie into a carabiner one-handed than most loop knots. Not only that, if you need to adjust your position after clipping in, the Clove Hitch is easily adjusted one-handed.

Ease of Untying

Not only ease of tying, but ease of untying a knot should be thought through, especially with wet rope or heavy loads. Once the knot gets loaded – or if it sees a heavy or shock load – will you be able to get the knot untied? Will you need to use a tool like the marlin-spike to get your loaded knot untied? How often will you be tying and untying the knot? Will the knot be wet or dirty? (Example: a loaded Bowline is easy to untie, while the Figure-8 Bend is more difficult.)

Knot Security

Knot security must always be considered but this is especially true if the knot will be subjected to tension and slack repeatedly. Will the knot be able to untie itself if it is cycled between tension and slack? (i.e., Square Knot vs. Figure-8 Bend) We know that a Butterfly Knot performs much better than a Figure-8 on-a-Bight if the knot is to be pulled in more than two directions. But what about some of the lessons learned over time that we know will make a difference in which knot to select based on other considerations. How difficult is it to untie a Figure-8 on-a-Bight after it has been loaded wet vs. a Two Loop Figure-8?

Tying a fixed line for a rappel? There are several choices to tie a fixed line instead of clipping it to an anchor strap. The Bowline, Clove Hitch, Figure-8 Follow-Through will all work, but if the line goes in and out of tension, how secure is the Clove Hitch compared to the Bowline or Figure-8? If security isn’t a concern, it will be easier to untie the Clove Hitch after it has been loaded followed by the Bowline, with the Figure-8 probably being the most difficult to untie, especially if the rope is wet.

Tying an anchor around a very large object? You will use up a lot more rope and time tying a Clove Hitch vs. a Figure-8 Follow-Through or a Bowline.

How will a knot handle a sustained load or shock load?

If you anticipate a heavy load on a Prusik Knot, consider making it a triple wrap instead of double. This will give you more friction, and it will definitely make it easier to untie later on. A little trick I use to loosen a loaded Prusik is to “push the bar.” By that, I mean to push the section of the knot that runs parallel to the rope that it is tied around away from the main line, which will loosen the knot.

The Water Knot is great for tying webbing together to form a runner or sling. But if it is really loaded, it can be a bear to untie. Try this, turn the knot so it is oriented vertically along its axis and place it between the palms of your hands. Rub your palms together squeezing on the knot and really be aggressive. After a few seconds, see if you are able to work a little looseness into the knot to start untying it. Same thing with a Figure-8 on-a-Bight, grasp the knot with both hands beside each other with half of the knot in each hand. Then, bend the knot back and forth as if you were activating a chem-light. Do this several times and see if you are able to milk a little slack into one side of the knot to start working it loose. Try to push slack into the knot instead of pulling the knot apart. Attack different parts of the knot until you see some movement.

Why Knot?

Fighting untying knots?

If you are fighting untying knots on a regular basis, it may be time to add a marlin spike to your kit. A marlin spike is a tapered tool that finishes with a blunt or flat tip. They have been around since ancient times and may be useful to get that first bit of looseness into the tight knot. The warning here is to never place the knot in a position that the spike could slip and puncture your leg or arm, always push the spike away from your body.

If you know you’re going to really load up your knot and especially if the rope is wet, consider clipping a carabiner into the bends of your knot between the lays. This works really well for the Figure-8 on-a-bight or follow-through. Once you are done with that knot, remove the carabiner – this may provide enough slack to work the knot out.

We generally advocate stuffing rope into a bag and working out of the bag, but sometimes we “coil” the rope to go from point A to point B. How often has this led to a bird’s nest of rope? To help prevent a coiled rope from tangling, hold the coil up in one arm and let it hang free. Uncoil the rope with the other hand not allowing the lines to cross. By holding the coil up, gravity will show you which sections are crossing. You will then be able to keep the line straighter than if you dropped the entire coil to the ground and just started pulling rope.

So, you can see there is a lot to think about and consider when choosing what knot you should use and why. As we said earlier, there are hundreds of knots to choose from and many of them do the same jobs. And many are called different names in different books. The key is to identify the category, the application and the circumstances where the knot will be used. Then consider the above and you should be able to identify the proper knot for the job at hand.

Visit our All About Knots page for videos on knot tying and much more!

Roco QUICK DRILL #9 - Belay Systems

Monday, November 30, 2015

Roco QUICK DRILL #9 - Belay SystemsDue to their relative simplicity, belay systems rarely see the dedicated training that is often given to the other elements of rescue, such as mechanical advantage or patient packaging. Just because you can rig a 540 Belay Device or tie a Munter Hitch does not necessarily mean you are proficient in their use.

It is important that the belayer can choose the proper belay system for the anticipated load and situation as well as understand the pros and cons of each system. Rescue teams must also be able to properly rig the system, troubleshoot any problems that might arise, catch the load and be able to safely transition from the "catch" to an emergency lowering system, if needed. 

There is a certain degree of finesse and anticipation involved with efficient belaying. It is an important skill only acquired through practice. Allotting more time to belay-specific training will provide payoff in smoother, safer operations during your next rescue.

1. As a team, discuss the belay needs of your environment (type of device or hitch, need for confined space rigging, high-point/low-point usage, one-person/two-person loads, etc.).

2. Divide your team into pairs and have each pair rig a specified device or hitch as a horizontal ground station.

3. While one member operates the device, the other attaches to the working end of the belay line and walks backwards to simulate a moving load. The team member on the line can also simulate a sudden load being applied to the rope at random intervals for the belayer to catch by pulling quickly on the working end of the rope.

4. If using the 540 Belay Device, develop proficiency in releasing a "stuck" load.

5. When using a Munter, work on body/hand position and tying off the Munter with a mule knot and releasing the mule knot while under load.

6. With tandem prusiks, practice converting to a lower system.

7. No matter what device or system, focus on maintaining a steady rate of rope progress through the device, while maintaining the proper amount of slack in the system (maximum 18 inches).

8. Have members switch positions and/or devices as they work on proficiency.

9. If time and training space allow, rig simple lower/haul scenarios where the emphasis will be on belay practice. In these scenarios, focus on the following:
       • Communication between the Rescue Master and the Belayer.
       • Maintaining the appropriate amount of slack in the belay system (no more than 18 inches).

Efficient belay skills are often taken for granted. Be sure to master the use of these critical, lifesaving systems!

 

Next in this series: QUICK DRILL #10 - Tripod Quick Drill

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Technical Rescue Incident Preparedness: Hazard Identification and Risk Assessment

Wednesday, July 8, 2015

Technical Rescue Incident Preparedness: Hazard Identification and Risk AssessmentWhether you’re a relatively new or a well-established Technical Search and Rescue (TSAR) organization, following an established Hazard Identification and Risk Assessment process is a great way to ensure you’re prepared for the “Big One."

The “Big One” is that incident where you’re called upon to deliver on the organizational investment of having a TSAR capability. A great deal of organizational time, money, and effort is invested in developing, maintaining, and deploying a Rescue Team. Plant Administrators, Fire Chiefs, and elected officials (private board members or public officials) want to see a return on that investment when their rescue service is called into action to save a life.  

The purpose of this article is to assist the Rescue Team Leader (RTL) and aspiring RTL (because we should always be developing our replacement) in establishing a Rescue Team, developing a new TSAR capability, or ensuring an established Rescue Team is adequately prepared for the “Big One."

Technical Rescue Incident Preparedness: Hazard Identification and Risk AssessmentFirstly, if there is a potential for a TSAR incident to occur within your jurisdiction, NFPA 1670 requires the authority having jurisdiction (AHJ) to address a number of “General Requirements” found in Chapter 4. The review and completion of these requirements are usually a function of the Rescue Team Leader along with key management personnel who authorize, budget, schedule, and equip the Rescue Team.

The format of Chapter 4 is useful for all Rescue Teams, whether newly formed or long established. It is an excellent tool for ensuring some of the foundational aspects of preparedness and organizational structure are (or have been) properly established.  Most “senior rescuers” (not those on Medicare but those that have the respect, time, and experience that makes them leaders in technical rescue) will tell you that the TSAR incident potential, including their hazards and risks, change as industrial processes are updated, installed, or eliminated. 

Key to all emergency response success is planning and preparation. However, incident preparation should be driven by the types of emergency incidents that have a potential for occurring within a given jurisdiction. This is the starting point for determining rescue capabilities, SOP/SOG’s, staffing, training, and equipment. 

Technical Rescue Incident Preparedness: Hazard Identification and Risk Assessment

The Hazard Identification and Risk Assessment is one method for assessing incident potential. NFPA defines:

•  Hazard Identification - The process of identifying situations or conditions that have the potential to cause injury to people, damage to property, or damage to the environment. 

•  Risk Assessment - An assessment of the likelihood, vulnerability, and magnitude of incidents that could result from the exposure to hazards. 

This process identifies the possibility of conducting TSAR operations within a jurisdiction by evaluating environmental, physical, social, and cultural factors that influence the scope, frequency and magnitude of a potential TSAR incident. It also addresses the impact the incident has on the AHJ to respond and conduct operations while minimizing threats to rescuers (NPFA 1670, 4.2.1 and 4.2.2). The standard lists a number of scientific methodologies in its annex but in the spirit of keeping it, we’ll approach this process using a Preliminary Checklist. (See Sample Checklist.)

Once completed, the checklist may have entries that require further analysis, identify a need to develop or expand a capability, or require entering into an agreement with an external resource. 

Technical Rescue Incident Preparedness: Hazard Identification and Risk AssessmentThis checklist is for day-to-day incident responses under predictable jurisdictional response conditions and should not be used for disaster scenarios where large scale regional and federal resources will be required to mitigate the incident. These scenarios should be addressed through Emergency Response Plans. 

Most fire departments and other emergency response organizations want to maintain a response capability that match potential incidents in order to be operationally effective, provide for rescuer safety, and have positive incident outcomes.  

A Hazard Identification and Risk Assessment is an excellent way to evaluate your organization’s preparedness level for technical rescue incidents based the potential for one to occur; it also aids in the development of specific capability. 

Roco QUICK DRILL #5 - Building Complete Rescue Systems

Thursday, October 16, 2014

Roco QUICK DRILL #5 - Building Complete Rescue Systems Due to time restraints in refresher training, oftentimes individual team members may only get to build a portion of a rescue system – for example, setting up a mainline or performing patient packaging. In order to have maximum team efficiency, it is important to keep all team members proficient in all aspects of the rescue operation.

1. Lay out enough equipment to build a mainline and a safety line system and for a particular type of packaging. Describe which system is to be used and how the patient will be packaged (i.e. vertical stokes raise, or horizontal SKED lower with attendant).

2. Identify what will be used as anchors. If working in a classroom or apparatus floor, a chair leg could be designated as bombproof or substantial anchor depending on the rigging the team member is being asked to do. If you are in the field, use whatever anchors are available.

3. Assign a team member to construct or rig the entire system on their own, including packaging the patient.

This drill allows a Team Leader to identify potential weaknesses in individual performance skills, while improving the team member's understanding of how the systems work. The knowledge gained will also help in planning future training sessions to correct any deficiencies. For the individual team member, this drill will reinforce all aspects of putting systems together and identifying weak points or areas of confusion that need to be corrected.    

 
Next in this series: QUICK DRILL #6 - Splitting One Rope Between Two Systems

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Can I Use a Crane as Part of my Rescue Plan?

Friday, October 3, 2014

This post has been updated and republished as of 30 Sep 2018.

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