Load safety6 min read
Blocking and Lashing for Crated Machinery: A Practical Guide
A container is a steel box that moves in six directions at sea. A crate is a mass with inertia. The gap between the two is blocking, bracing and lashing, and it is the part of the plan most often left to improvisation.
Start with the container, not the cargo
Lashing points are part of the container specification, and their positions and working load limits vary. Before designing the lashing plan, confirm what the box actually offers, including the condition of the D-rings. A plan that assumes twelve sound lashing points on a container with six is a plan that will be improvised on the dock.
Block before you lash
Timber blocking against the container walls, or against other cargo, carries most of the longitudinal load. Lashings hold the cargo down and stop it lifting or shifting laterally; they are not a substitute for blocking a 12 t unit.
For heavy crates, the sequence is: block the base against fore and aft movement, brace the sides so the crate cannot rotate, then lash down to the floor points. Nailing blocks into the container floor is not permitted on most boxes; use friction mats, purpose-made wedges or shoring beams instead.
Dunnage is not padding
Dunnage fills the gap between cargo and structure so that movement never starts. Airbags are effective for wide gaps and light cargo; they are not a fixing method for a machine. Timber dunnage should bear on the crate frame, not on a panel that will crush.
Watch the door end
The door end is where a load most often fails, because the last items loaded have the least blocking behind them and the doors open onto the destination yard. Keep a clearance zone of at least 100 mm behind the doors for opening, and brace the last row so nothing can lean out when the bars come off.
What the plan should show
- Lashing point positions in container coordinates, matched to the crate's own anchor points.
- The blocking pattern for each heavy item, with timber sizes where they are specified.
- Where dunnage or airbags are required, and where they must not be used.
- A note on the maximum gap allowed between the last row and the door.
Then check it on the day
The plan is a reference, not a certificate. The person closing the doors is the last control point: confirm the blocking is tight, the lashings are tensioned, the door clearance is real, and the seal number matches the paperwork before the container leaves the yard.
Put these numbers on a real plan
The calculator applies the 40% centre of gravity rule and the 60% half-load rule to your own packing list, free for three runs a month.