Loops et estropes

In the realm of rigging and sailing, spliced loops and strops play a crucial role, providing secure and reliable connections in various applications. Understanding the differences between spliced loops and strops, along with their break strength and important considerations, is essential for ensuring safety and efficiency in rigging operations. Below we discuss these aspects, offering valuable insights for both novice and experienced riggers.

Key Differences Between Spliced Loops and Strops

We refer to Dyneema® Spliced loops which are a loop of continuously wound fiber, with a braided cover, which can be used in a number of different configurations, as anchor points. These are different to what we, at Upffront refer to as Dyneema® Strops which are a length of Dyneema® fiber with an eye at each end and more commonly used as a link in a system. Key Differences:

• Construction: Spliced loops are created by winding a two (thread) of usually Dyneema® fibre in a continuous loop, and covered by a braided cover layer, forming a seamless and strong connection Strops can be formed in two main ways. A long continuous loop can have the two legs braided together through the central section, leaving at loop at each end or a simpler, more cost effective solution is to use a length of single braid Dyneea® core and making an eye splice at each end. These are quick and simple to make and provide an incredibly flexible and versatile tool for integrating into many sailing systems.
• Strength and Durability: Spliced loops tend to exhibit higher strength and durability compared to strops due to their seamless construction. The absence of knots in spliced loops eliminates potential weak points, ensuring uniform strength throughout the loop.
• Versatility: While both strops and spliced loops serve similar purposes as attachment points in rigging operations, spliced loops offer more integrity and safety for structural rigging applications. Strops on the other hand ca be quickly built and adapted for more dynamic applications.

What is the Break Strength of a Dyneema Spliced Loop or Strop?

The break strength of a strop or Dyneema spliced loop refers to the maximum amount of force it can withstand before failing or breaking. This critical parameter determines the safety and reliability of the loop in rigging and lifting operations. However, Strops and spliced Loops should be specified to a Safe, or Maximum, Working Load (SWL/MWL) in line with other elements of the system. This SWL may be 10-25% of the Break Load (BL), the difference between the two being the Factor of Safety (FOS). 

The break strength of strops can vary depending on factors such as the type of fiber used, construction method, and quality of materials. Spliced Loops and Strops can both be used in various configurations, the primary of which are Straight, Basket and Cow-hitch. If we take a 6mm diameter loop (i.e. the cross section of the fiber bundle) a straight loop will have roughly double the break strength of a standard 6mm Dyneema® rope, because there are x2 legs of 6mm fiber carrying the load. The basket configuration will have twive the break strength of the straight loop because there are x4 legs of load carrying fibre, The cow-hitch itself is a weakpoint and generally will have approx. 20% less breakstrength than the straight confuration.

Dyneema spliced loops, crafted from Dyneema® fiber renowned for its exceptional strength-to-weight ratio, offer impressive break strengths. These loops undergo rigorous testing to ensure they meet specified strength and performance standards, making them reliable components in rigging and sailing applications.

Important Considerations When Using Soft Connections

1. Load Distribution:

   Proper load distribution is crucial when using soft connections like spliced loops or strops. Ensure that the load is evenly distributed across the loop to prevent excessive stress on any single point.

2. Radius of anchor points:

Dyneema® has one weaknesses – it doesn’t like sharp corners. Special care should be taken to ensure as large a radius as possible for the Dyneema to sit on. However, on the test bed, it has been proven that a minimum radius of 1:1 will not negatively impact loop strength.

3. Inspection and Maintenance:

   Regular inspection and maintenance of soft connections are essential to identify signs of wear, abrasion, or damage. Having said that, soft connections are very maintenance friendly i.e. if there are no signs of abrasion then you can be confident of the loops structural integrity. This is not always the case with wire and rod where problems can be hidden out of sight until a critical failure occurs.

Replace any worn or damaged loops immediately to maintain safety and reliability in rigging operations.

4. Environmental Factors:

   Consider environmental factors such as UV exposure, saltwater corrosion, and abrasive anchor surfaces when selecting and using soft connections. Choose materials and constructions that are resistant to these elements to ensure long-term durability and performance.

5. Proper Sizing and Configuration:

   Select the appropriate size and configuration of spliced loops or strops based on the intended application and load requirements. Avoid overloading as this can compromise its strength and reliability.

6. Professional Guidance:

   When in doubt, seek guidance from experienced riggers or industry professionals. They can provide valuable insights and recommendations for selecting, installing, and using soft connections effectively and safely.

In conclusion, spliced loops, strops play vital roles in rigging and sailing applications, offering secure and reliable attachment points for various tasks. Understanding the differences between these soft connections, along with their break strength and important considerations, is essential for ensuring safety, efficiency, and performance in rigging operations. By adhering to proper practices and guidelines, riggers can harness the full potential of Dyneema® spliced loops and strops, enhancing safety and reliability in any rigging endeavor.