What is the efficiency of a round turn with two half hitches?

The efficiency of a round turn with two half hitches is typically around 75%. This efficiency reflects how effectively the knot can hold a load while minimizing the potential for slippage or failure under tension.

A round turn essentially provides friction and distributes the load across a larger surface area, reducing stress on any single point. The addition of two half hitches secures the knot further, enhancing its ability to resist load movement and helps maintain stability.

While options representing lower efficiencies suggest that knots may not hold significant weight securely, the round turn combined with the two half hitches benefits from the increased friction and secure nature of the hitches, allowing for that higher operational efficiency. Thus, 75% is a practical and commonly accepted value for this knot's efficiency in rigging applications.