What is the device used to adjust the tension or length of rigging lines by turning the body or end fittings?

• A. Rope lock
• B. Turnbuckle
• C. Loft block
• D. Main line

Answer: (B)

Turning the body or end fittings of a device changes how far the threaded ends engage, which shortens or lengthens the line and thus adjusts tension. That behavior is characteristic of a turnbuckle, a hardware piece with a threaded barrel and opposite-threaded ends that you rotate to tighten or loosen the rigging. A rope lock merely grips rope to hold it in place, not to adjust length. A loft block is a pulley used to redirect a line, changing direction rather than tension. The main line is the rope itself, not a device for adjustment. So the turnbuckle is the tool used to finely tune tension and length in rigging.