Swiftwater Rescue Mobility Techniques: Line Crossing and Diagonal Traverse

Swiftwater rescue operations require precise techniques to ensure the safety of rescuers and victims. Besides traditional wading or swimming, two advanced techniques stand out: line crossing and diagonal traverse. Both methods utilize a rope line or throw bags, adding an extra layer of control and stability when moving across fast-moving water. This guide explores these techniques in detail, providing specialized knowledge on their application, advantages, and potential risks.

Line Crossing: A Stable Method for Crossing Water

Line crossing is a method where a stationary rope is stretched across the water to provide stability while crossing. The rope is tied securely to natural anchors such as trees or rocks on either side of the river. In rescue operations, a belayer is often involved. The belayer, a person responsible for securing the rope, uses a sitting belay, a technique where they sit while anchoring the line. This method helps prevent the belayer from being pulled into the water by sudden force, such as a person losing balance in fast currents.

To secure the belayer, a backup is critical. A carabiner can be used to further stabilize them, ensuring that they don’t fall into the water. This adds an extra layer of safety, particularly in rescue situations where the terrain or water conditions are unpredictable.

Tips for Effective Line Crossing

One of the most important aspects of line crossing is applying the right tension to the rope. Adequate tension ensures stability for those crossing. If the rope is too slack, it can wobble, making the crossing unstable and dangerous. The line should be tight but not overstretched, allowing some flexibility.

When wading across using the rope, it’s important to avoid crossing your legs, as this can reduce stability. Instead, rescuers should move one foot at a time: advance the left foot, then bring the right foot closer without crossing them. This technique minimizes the risk of stumbling and helps maintain balance in the fast-flowing water.

Advantages of Line Crossing

Stability: The rope provides a firm anchor point for individuals crossing turbulent waters, reducing the risk of slipping or losing balance.
Versatility: This method can be adapted to various water conditions and can be used with minimal equipment.
Safety: By anchoring the rope to solid structures and securing the belayer, this method significantly reduces the risk of falling into the water.

Disadvantages and Cautions

Complex Setup: Finding appropriate natural anchors on both sides of the river can be challenging, particularly in rough terrain.
Belayer Risk: Despite backup systems, there’s still a risk of the belayer being pulled into the water, especially in strong currents. Proper training is essential to mitigate this risk.

Diagonal Traverse: Harnessing the Power of the Current

In contrast to line crossing, diagonal traverse leverages the power of the river’s current to aid in moving a swimmer across the water. This technique involves setting a rope at an angle relative to the flow of the river. By maintaining this angle, the current can help push the swimmer along the line, reducing the physical effort required to cross.

To set up a diagonal traverse, a rope is tied at an angle to natural anchors on either side of the river. A belayer may also be used, and the same safety protocols as line crossing, such as the use of a carabiner, should be followed. The primary difference is the length and tension of the rope. A diagonal traverse typically requires a longer rope, often exceeding the length of a single throw bag. Multiple throw bags should not be tied together, as this could interfere with the carabiner’s ability to slide smoothly along the line. However, the line can be extended by attaching additional throw bags at either end.

How Diagonal Traverse Works

Once the line is set, the swimmer attaches their rescue vest’s carabiner to the rope. By positioning their body correctly and maintaining a ferry angle—a technique where the swimmer angles their body against the current—they can use the force of the water to carry them across the river. The swimmer should keep their head facing the bank and adjust their body angle to ensure a smooth and controlled crossing.

Advantages of Diagonal Traverse

Efficient Use of Current: The diagonal traverse allows the swimmer to take advantage of the river’s natural flow, reducing physical exertion.
Longer Reach: This technique is ideal for wider rivers where other methods may fall short due to rope length limitations.

Disadvantages and Cautions

Longer Setup Time: Setting up a diagonal traverse requires careful planning and adequate rope length, which can slow down rescue operations in urgent situations.
Risk of Misalignment: If the ferry angle is incorrect, the swimmer may drift off course, potentially increasing the time spent in the water and heightening the risk of fatigue.

Line Setup Methods: Throwing, Swimming, and Boating

There are multiple ways to establish a line across a river. The most common and efficient method is throwing a rope. A throw bag is tossed across the river to a person on the opposite side, and the rope is anchored. The higher the thrower’s position, the further the bag can be thrown. If the throw doesn’t reach the opposite bank, a paddle can be used to extend the reach.

If throwing isn’t successful, swimming across the river may be required. The swimmer carries the line across the river, attaching it to their quick-release tether on their rescue vest using a carabiner. It’s important not to tie the line directly to the swimmer, as this can restrict movement and increase the risk of entanglement.

A key technique during swimming is the rescue dive—where the swimmer enters the water belly-down, protecting their face with both hands. Aggressive swimming is needed to overcome strong currents and reach the opposite bank. Once the swimmer secures the line, slack can be adjusted, and additional throw bags can be clipped to the line to extend its length if necessary.

Final Thoughts

Both line crossing and diagonal traverse are essential swiftwater rescue techniques that add safety and control to potentially hazardous situations. While each method has its advantages, proper training and equipment are critical to their successful application. Rescuers must also be aware of the challenges and risks involved, taking the necessary precautions to ensure the safety of everyone involved.

References
Kaufman, R. (2015). Swiftwater rescue packet. McHenry, MD: Garrett University.
Walbridge, C. and Sundmacher, W. (1995). Whitewater Rescue Manual – New Techniques Canoeists, Kayakers, and Rafters.
Camden, Maine: Ragged Mountain Press.

FIRE RESCUE CLUB

Swiftwater Rescue Mobility Techniques: Line Crossing and Diagonal Traverse