Blocking / bracing / dunnage refer to the materials and methods used to secure cargo within a shipping unit (such as a container or flat rack) or a vessel’s hold to prevent movement, shifting, or damage during ocean transit. They are mandatory safety components required by U.S. carriers and regulatory bodies.
- Dunnage: Inexpensive, loose material, such as wooden planks or inflatable air bags (air dunnage bags), used to fill small voids, absorb shock, and protect the cargo from direct contact with other surfaces or with the vessel’s structure.
- Blocking: Using solid lumber or custom-built wooden chocks to create rigid structures that physically block the movement of cargo away from the container walls or the floor.
- Bracing: Using steel strapping, wire, or heavy nylon straps anchored to lashing points (bull rings) to tighten and brace the cargo against the blocking or container structure, preventing forward, lateral, or vertical shifting.