What does the 3:1 cribbing rule relate to?

• A. The recommended maximum crib height relative to the base load to prevent tipping; often used as a guideline for stability.
• B. The ratio of rope length to height.
• C. The ratio of number of rescuers to victims.
• D. The ratio of cribbing width to base area.

Answer: (A)

The 3:1 rule is about keeping cribbing stable by limiting its height relative to the base footprint. In cribbing practice, you want the stack to be no taller than about three times the width (or footprint) of the base. This ratio helps ensure the setup won’t tip or shift when a load sits on it or when forces come from changing angles, making the support predictable and safer.

In practical terms, if your base width is, say, 6 inches, you’d aim for a cribbing height of roughly 18 inches or less. If you needed a taller setup, you’d widen the base or add more layers to keep the ratio within about 3:1.

This concept isn’t about rope length, the number of rescuers to victims, or base area measurements unrelated to height. It specifically ties the height of the cribbing to how broad its base is to maintain stability under load.