Two-Rope Offset System

The two-rope offset system is a practical and efficient technique for moving loads across challenging terrain, such as canyons or gaps, without introducing the high tensions typical of highline systems. By leveraging two rope systems on either side of the gap, this method ensures a safe, controlled transfer of the load while minimizing the risks associated with high tension. Here’s an in-depth look at the setup, operation, and advantages of the two-rope offset system.

What is a Two-Rope Offset System?

At its core, a two-rope offset system combines two independent two-rope setups working together to lower a load down one side of a gap and haul it up the other side. Unlike a highline system, this technique does not require the load to remain elevated above the gap; instead, the load stays close to the terrain, simplifying the system and reducing tension.

Key Components:

• Lowering System: Operated by the team on the starting ledge, this system manages the descent of the load into the gap.
• Hauling System: Managed by the team on the opposite ledge, this system pulls the load across and up the other side.

The difference between a two rope offset system and a highline system is there’s much lower tensions involved. Only the amount of tension required to keep the load off of the terrain and moving down and then across and then back up the other side of the terrain, only that amount of tension is required. We’re not trying to span any gaps by keeping the load elevated above the gap itself.

We basically have is a two rope system, whether that’s the two tension rope system or a traditional loaded main and unloaded belay system for lowering the load down one side of the gap.

The way the  two ropes system will work together is as a load is lowered down one side of the gap, it’s going to be hauled up on the other side of the gap. If for instance, our load started here on this ledge, the black circle is just to symbolize whatever the two rope system is that we’re working. Again, it could be a two tension rope system working through two super munters or two MPDs or it could be a loaded main working through a break bar rack and an unloaded belay within a tandem prusik setup.

The load’s going to be lowered down the side of the gap. We’ll call this a canyon, and it’s going to be simultaneously hauled up the other side of the canyon.

The team that’s working here on this ledge (Ledge 1), they’ve got a lowering system in place. They lower the load down. The team over here on this ledge, they have a haul system in place. They begin by hauling the load out from the face of the side of the canyon. When the load gets to the bottom of the canyon, the the team over here starts to haul. They haul the load across the canyon up to the other side, and then it starts to look like a more traditional just vertical haul.

With the team over here (Ledge 2) continuing to just apply enough tension to the load to keep it off the face over here. The key with the two rope offset is you always want to keep the load as close to the terrain as possible. We’re not looking to fly the load across the canyon. We just want to keep it off the terrain. We have water at the bottom, for instance, just keep it above the water and then keep the load just off the other side of the canyon.

The benefit of doing this is that we avoid introducing the high amounts of tension that are associated with high line systems. You’ll notice here the angle that the two lines form at the litter, is an acute angle. We’re not approaching at 120 degree magic angle that we shoot for with highline systems. It tends to stay a much tighter angle throughout the evolution.

So to conclude, the two rope offset system, it’s a system that we can set up to move a load across a gap, for instance a canyon. The system requires a team operating a two rope system, a main and belay or a two tension rope system on one side of the gap, and a team operating an identical two rope system on the other side of the gap. One team is going to lower out while the other team simultaneously hauls in.

Communication is going to be really important in this because there needs to be a lot of coordination between the two teams. The objective, again, is to keep the load just off the terrain. We’re not trying to fly the road across like we would with a high line and the benefit of this is that we’re going to have much lower tensions involved and this could be a much safer system to operate.

How the System Works

1. Lowering the Load:
   • The load begins at the starting ledge, where the lowering team uses a two-rope system to control the descent.
   • This system could include:
     • A two-tension rope system using devices like super munters or MPDs.
     • A loaded main and unloaded belay setup, utilizing a brake bar rack and tandem prusiks for safety.
2. Hauling Across the Gap:
   • Simultaneously, the hauling team begins to pull the load out from the canyon face and towards their ledge.
   • The load is kept just above the terrain or water at the bottom of the gap.
3. Transition and Vertical Haul:
   • Once the load reaches the bottom of the canyon, the hauling team transitions to a vertical haul.
   • The lowering team maintains just enough tension to keep the load from making contact with the terrain on their side.
4. Key Objective:
   • Keep the load close to the terrain, avoiding unnecessary elevation. This minimizes tension on the system and ensures smoother operation.

Advantages of a Two-Rope Offset System

1. Lower Tensions:
   The acute angle of the ropes at the litter reduces the tension compared to highline systems, making it safer and more manageable.
2. Efficient Use of Terrain:
   The load is kept close to the ground, leveraging natural contours to guide the transfer.
3. Simpler Rigging:
   Without the need to keep the load elevated, the system avoids the complexity and high forces associated with spanning a gap.
4. Versatility:
   Works equally well in water rescue scenarios or terrain-based extractions.

Critical Considerations

1. Communication is Key:
   • Coordination between the lowering and hauling teams is crucial for a smooth evolution.
   • Consistent communication ensures proper timing and tension control.
2. Equipment and Setup:
   • Use reliable devices for progress capture, such as MPDs, brake bar racks, or prusiks.
   • Ensure ropes are appropriately tensioned to prevent slack or excessive force.
3. Acute Angles:
   • Maintain a tight angle at the litter to avoid the high forces seen with wide-angle setups in highline systems.

Real-World Applications

The two-rope offset system is particularly useful in scenarios where:

• High tension is a concern: Such as in unstable anchor environments.
• Minimal elevation is needed: Keeping the load close to the terrain reduces the complexity of the operation.
• Terrain dictates the approach: For example, water at the base of the gap or steep canyon walls.

Conclusion

The two-rope offset system is an essential tool in the rigger’s and rescuer’s repertoire. Its ability to safely and efficiently move loads across challenging gaps, combined with its simplicity compared to highline systems, makes it a versatile and effective choice. However, its success depends on precise communication, proper rigging, and a thorough understanding of the terrain and load dynamics.

To explore this technique further and see a demonstration, visit the resources available at Rigging Lab Academy.

Peace on your Days
Lance