On your vessel, a wire rope for the cargo gear shows signs of excessive wear and must be replaced. In ordering a new wire for this 10-ton boom, what safety factor should you use?
• Safe working load (SWL) vs. breaking strength of wire rope • Typical safety factors for cargo handling gear (booms/derricks) used for lifting loads • Regulatory/standard practice requirements for wire rope used in cargo gear on merchant vessels
• Think about how critical a 10‑ton boom is for safety: would regulations allow a low, medium, or high safety factor for lifting heavy loads over the ship and pier? • Compare common safety factors for standing rigging, towing wires, and cargo-lifting gear— which one usually requires the highest margin of safety? • Consider what would happen if the load swings or shocks the wire: how much extra strength above the working load should the rope have?
• Verify what safety factor is commonly specified for cargo derrick/boom wire ropes in merchant marine exam study guides or regulations • Confirm that the chosen factor means: Breaking strength = safety factor × safe working load (10 tons) • Eliminate any option that seems clearly too low for lifting people or loads over a working area, given potential shock loading and wear
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