By what percentage does fiber rope derate when tying a bowline knot?

When tying a bowline knot in fiber rope, the rope's strength is significantly reduced due to the nature of the knot and how it sits under load. The bowline is a type of knot that creates a fixed loop at the end of a rope, but it does not grip the rope tightly. This design allows for ease of untying but comes with a trade-off in terms of strength.

Research and industry standards indicate that tying a bowline knot can reduce the strength of the rope by approximately 40-50%. Therefore, a reduction of around 45% falls well within the commonly accepted norms for the bowline knot. This percentage accounts for how the knot creates stress points and alters the load distribution on the rope fibers, leading to a significant derating of its overall strength when compared to its unknotted state.