🔍 Key Concepts

• Relationship between line diameter and sheave diameter in standard rigging practice • Rule-of-thumb for sizing a sheave for natural fiber lines (like manila) • Difference between cheek size (overall block length) and sheave size (wheel diameter)

💭 Think About

• First, convert the 3-inch circumference of the manila line into its approximate diameter. What simple formula relates circumference to diameter? • Once you know the line’s diameter, recall or look up the common rule-of-thumb: the sheave diameter should be how many times the line diameter for manila? • Compare that recommended sheave diameter to each choice and decide which option best matches standard safe practice for manila line.

✅ Before You Answer

• Be sure you are sizing the sheave, not the cheek – cheek length is usually larger than the sheave diameter. • Verify the circumference-to-diameter conversion before you apply any rule-of-thumb. • Check that the chosen sheave size is large enough to avoid sharply bending the manila line, which can weaken it.