What is the maximum included angle for hooks with a row sling rigging?

What is the maximum included angle for hooks with a row sling rigging?

• A. 45°
• B. 60°
• C. 90°
• D. 120°

Answer: (C)

In row sling rigging, how spread the sling legs are directly affects how much force each leg must carry to lift the load. When the legs diverge, the load path creates more horizontal pull on the rigging and increases the tension in each leg. For two equal legs, the load W is supported by the vertical components of the leg tensions, so W = 2 T cos(θ/2), where θ is the angle between the two legs. Rewriting, the tension in each leg is T = W / (2 cos(θ/2)). As θ increases, cos(θ/2) decreases, so the required T rises. Up to 90 degrees, cos(θ/2) is at least cos(45°) = 0.707, keeping the leg tension within typical ratings (about 0.707 of the load per leg). If the included angle goes beyond 90°, the required tension grows more quickly and can exceed the hook and sling ratings, increasing the risk of failure and instability. That’s why the practical maximum for a row sling is 90 degrees—staying at or below this angle helps maintain safe, rated capacities and stable load handling.

In row sling rigging, how spread the sling legs are directly affects how much force each leg must carry to lift the load. When the legs diverge, the load path creates more horizontal pull on the rigging and increases the tension in each leg. For two equal legs, the load W is supported by the vertical components of the leg tensions, so W = 2 T cos(θ/2), where θ is the angle between the two legs. Rewriting, the tension in each leg is T = W / (2 cos(θ/2)). As θ increases, cos(θ/2) decreases, so the required T rises. Up to 90 degrees, cos(θ/2) is at least cos(45°) = 0.707, keeping the leg tension within typical ratings (about 0.707 of the load per leg). If the included angle goes beyond 90°, the required tension grows more quickly and can exceed the hook and sling ratings, increasing the risk of failure and instability. That’s why the practical maximum for a row sling is 90 degrees—staying at or below this angle helps maintain safe, rated capacities and stable load handling.