Rigging math clicked after a 80 ton pick in Boise

I used to eyeball sling angles. Thought charts were for the office guys. Then last month we set a big HVAC unit on a hospital roof. I rigged it with four legs at a sharp angle. The site engineer stopped the lift. He showed me the load on each leg was double what I figured. We re-rigged it with longer slings. Took an extra 20 minutes. That pick went smooth. Now I double check every angle with the chart before I signal. Has anyone else had a close call that made them trust the numbers over gut feel?

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miab8718d ago

Same thing happened to me on a tank job, the math showed way more tension than my gut said.