Which of the following correctly describes a method to determine the minimum blocking surface area under outriggers?

• A. Multiply the outrigger float area by 3 and divide the maximum capacity by 5 (for square feet)
• B. Add 5 square feet to the outrigger area
• C. Use the crane's wheelbase as the basis
• D. Rely on experience without calculations

Answer: (A)

The idea is to ensure a stable base by linking the actual outrigger footprint to the load the crane is planning to lift. By multiplying the outrigger float area by three, you introduce a safety margin to account for ground unevenness, mat thickness, and dynamic forces during lifting. Dividing the crane’s maximum capacity by five translates the lifting load into a conservative minimum base area, recognizing that heavier lifts require more footprint to keep ground pressure within safe limits. Using both pieces together yields a dependable minimum blocking surface area that protects against ground failure or tipping, regardless of small variations in ground conditions. The other approaches don’t balance the footprint with the load: a fixed add-on ignores lift weight; relying on wheelbase misses how the outriggers and ground conditions interact with capacity; and doing no calculations at all ignores the safety margins built into practice rules.