Previous Articles on Rescue Rope

• A Rescue Rope and Cord Overview
• Rescue Rope Construction
• Rescue Rope Frequently Asked Questions

Rope Diameter

The rope diameter refers to the width of a rope, measured in inches or millimeters. While American manufacturers commonly use inches, European manufacturers rely on millimeters. NFPA 1983 standards use metric sizing and round up to the nearest half millimeter.

Key Considerations for Rope Diameter:

• Larger Diameter Ropes: Provide greater strength and more friction, which slows rappelling.
• Smaller Diameter Ropes: Lighter, less expensive, and ideal for applications requiring portability.

Choosing the right diameter depends on your needs—whether it’s strength, weight, or cost efficiency.

Sheath Construction

The design of a rope’s sheath influences several key factors:

1. Torque Resistance: Higher strand count sheaths exhibit less rotation under load.
2. Flexibility: A 16-strand sheath is more flexible but prone to knot jamming, while a 48-strand sheath offers superior handling with reduced kinking.
3. Knotability: Higher strand count ropes tend to knot more efficiently and jam less.

Sheath Slippage One common issue with kernmantle ropes is sheath slippage, where the outer sheath slides past the core, particularly at the rope ends. This can:

• Increase the rope’s diameter and jam pulleys or prusik hitches.
• Be mitigated by choosing well-constructed ropes or trimming and sealing affected areas with a hot cutter.

Abrasion Resistance

Abrasion resistance determines a rope’s ability to withstand wear and friction, which is critical for rope rescue applications.

Factors Influencing Abrasion Resistance:

• Fiber Content: Synthetic fibers like nylon and polyester excel in abrasion resistance.
  • Nylon: Strong, durable, and smooth, offering high resistance to abrasion.
  • Polyester: Durable with minimal stretch but slightly less abrasion resistance than nylon.
  • Kevlar®: Exceptionally strong and abrasion-resistant, ideal for extreme conditions.
• Yarn Structure: Twisted yarns resist abrasion better than braided yarns.
• Fabric Structure: Tightly woven sheaths outperform loosely woven designs in abrasion resistance.
• Treatments: Lubricants, wax coatings, or polymer treatments can enhance resistance.

Elongation

Elongation (or stretch) is the rope’s percentage increase in length under load. It is a key factor in technical rope rescue:

Static Rope

• Elongation: 6-10% under 10% of Minimum Breaking Strength (MBS).
• Use: Anchors, rappelling, and hauling systems where minimal stretch is required.

Dynamic Rope

• Designed for energy absorption, with higher elongation to cushion falls.
• Use: Applications with fall potential, such as belay systems.

Practical Considerations:

• During rappels, load transfer from the ground to the rope causes descent proportional to elongation.
• Awareness of elongation ensures controlled operations, whether lowering a litter or arresting a fall.

Energy Absorption

Energy absorption distinguishes static and dynamic ropes:

• Static Rope: Minimal energy absorption, making it unsuitable for dynamic loads (e.g., falls).
• Dynamic Rope: Designed to absorb fall energy by stretching, reducing impact forces and preventing injuries.

For technical rescue, understanding energy absorption ensures the correct rope selection for safe and efficient operations.

And Now Something on Webbing!

Courtesy of CMC

Flat Webbing

Flat webbing is ideal for situations requiring secure knots. Its suppleness allows for:

• Easier knot setting.
• Simplified untying after heavy loads.

While bulkier than tubular webbing, flat webbing provides higher strength and knot reliability, making it a preferred choice for anchor systems.

Tubular Webbing

1” Tubular Webbing is popular for its strength and durability, especially in military and rescue operations. Key benefits include:

• Mil-Spec Webbing: Meets strict standards for extreme durability.
• Strength: Tested to breaking strengths exceeding 4,000 lbs.

Use Case: Tactical and high-stress environments where reliability is non-negotiable.

Sewn Slings

Sewn slings are favored for anchors due to their:

1. High Strength: Capable of holding heavy loads up to 5,000 lbs or more.
2. Ease of Use: Quick to adjust and secure at anchor points.
3. Portability: Lightweight and compact for easy transport.

Examples:

• CMC Texora Sling: Ultra-strong for life safety applications.
• Sterling 1” Flat Nylon Sling: Durable and versatile for technical rescue needs.

Key Takeaways

• Rope Diameter: Affects strength, weight, and handling.
• Sheath Design: Influences flexibility, knotability, and torque resistance.
• Abrasion Resistance: Determined by fiber type, weave, and treatments.
• Elongation: Static ropes offer minimal stretch; dynamic ropes absorb energy for fall protection.
• Webbing: Choose flat or tubular webbing based on strength, knots, and application needs.

For further exploration into rescue ropes, webbing, and technical rescue systems, visit Rigging Lab Academy.

Previous Articles on Rescue Rope

• A Rescue Rope and Cord Overview
• Rescue Rope Construction
• Rescue Rope Frequently Asked Questions

Peace on Your Days
Lance