For optimum rope efficiency, the maximum fleet angle should be what?

• A. 0.5 degrees
• B. 1 1/2 degrees
• C. 2 degrees
• D. 1 degree

Answer: (B)

Keeping the fleet angle small is key to rope efficiency. The fleet angle is the angle between the two portions of a rope as it exits or enters a turning point like a capstan, block, or fairlead. When that angle is larger, the rope bends more around the drum and there’s more rubbing and slipping between the rope and the sheave surfaces. That extra bending and friction waste force as heat and can cause uneven loading, reducing the effective pull you get from the rope.

For optimum efficiency, you want that angle limited to about one and a half degrees. Staying at or below this keeps friction losses to a minimum while still allowing the necessary routing. Angles larger than about 1.5 degrees raise friction and reduce efficiency, while smaller angles (though safer) are not the maximum efficiency limit. So the best maximum value to aim for is one and a half degrees.