🔍 Key Concepts

• Container stack behavior in heavy seas or during ship motions • Difference between crushing, racking, buckling, and toppling as structural failure modes • Purpose of lashings vs. interlocking fittings (twistlocks) on container stacks

💭 Think About

• Think about what interlocking fittings (twistlocks) already prevent by themselves before lashings are added. What extra problem do lashings specifically address? • Visualize a tall stack of containers when the ship rolls heavily to one side. How would the stack want to move or deform if there were no lashings? • Which of the four failure modes is mainly about the whole stack shifting side‑to‑side as a unit, rather than the walls of a container being crushed or bent?

✅ Before You Answer

• Be clear on the definition of crushing (compression failure), buckling (bending or instability of slender members), racking (distortion of a rectangular frame into a parallelogram), and toppling (overturning). • Ask: Do lashings mainly stop vertical compression, sideways frame distortion, local panel bending, or the stack from leaning and falling? Match that to the best term. • Remember that interlocking fittings already give vertical alignment and stacking. Lashings add restraint against lateral and overturning forces from wind and vessel motion.