How to Pack a 40ft Open Top Container
Step-by-step loading guide - crane loading, tarpaulin securing, OOG cargo handling, and weight distribution for a 40ft Open Top container
Internal dimensions
12.03m × 2.35m × 2.33m
Usable volume
66.0 m³
Max payload
26,630 kg
Tare weight
~3,800 kg
Max load height
2.33m (open top)
Step-by-step packing guide
Plan crane access and lifting sequences
Open Top loading requires careful crane planning. Determine whether cargo will be loaded through the doors (standard forklift), from the top (crane), or both. Book crane capacity in advance — you will need a crane with sufficient reach and lifting capacity for your heaviest single piece. Plan the loading sequence so that items loaded by crane go in first (they will be at the bottom or back), with door-loaded items last.
Inspect the container, tarpaulin, and roof bows
Check the container body for structural damage, especially the top side rails which bear the tarpaulin load. Inspect the removable roof bows — they must lock securely into position. Examine the tarpaulin for tears, holes, and grommet damage. Check that all tarp tensioning ropes and toggles are present and functional. A damaged tarp means water damage to your cargo — reject any container with a defective tarpaulin.
Load over-height cargo by crane
With the roof bows and tarpaulin removed, lower cargo in from the top using appropriate slings or spreader bars. Position over-height items first, centered left-to-right for stability. If cargo extends above the side rail height (2.33m), it is classified as Out of Gauge (OOG) and will incur surcharges and special stowage on the vessel. Ensure no cargo contacts or damages the side rails during crane operations.
Protect cargo from weather exposure
Unlike standard containers, Open Tops expose your cargo to rain and sea spray during loading, port storage, and any time the tarp is removed. Wrap sensitive cargo in waterproof sheeting before loading. For machinery and metal goods, apply corrosion inhibitors and use VCI (Vapor Corrosion Inhibitor) packaging. Never assume the tarpaulin alone provides adequate weather protection — it is a secondary barrier only.
Secure cargo to lashing rings and side rails
Open Top containers have additional lashing points along the top side rails specifically for over-height cargo. Use heavy-duty ratchet straps or chains rated for the cargo weight. Cargo must be secured against movement in all six directions — forward, backward, left, right, up, and down. For OOG cargo extending above the rails, coordinate with the carrier for vessel-specific securing requirements.
Refit tarpaulin, seal, and document
Replace the roof bows in their correct positions and spread the tarpaulin over the top. Tension all ropes and toggles evenly — a loose tarp flaps in transit and will tear. Ensure the tarp overlaps the side rails with no gaps. Photograph the loaded container from above (if possible) and from the door end. Document OOG dimensions precisely — the carrier needs exact measurements for vessel stowage planning.
Weight distribution rules
Center heavy cargo for crane stability
When loading by crane, heavy items should be placed as close to the longitudinal center as possible. Unlike door-loaded cargo where you work front-to-back, crane-loaded items land wherever the crane places them. An off-center heavy item creates a dangerous imbalance during subsequent crane lifts of the container itself.
Secure against uplift — there is no roof
In a standard container, the roof prevents upward movement. An Open Top has no structural roof — only a tarpaulin. Lighter items on top must be lashed down, not just wedged in. Wind forces during ocean transit can be severe, and anything unsecured can lift out of the container.
Account for OOG cargo weight above the rail line
If cargo extends above the 2.33m side rail height, the weight above the rail line creates additional tipping force. Inform the carrier of the exact over-height dimensions and weight. The vessel stowage planner needs this data to assign the correct cell and lashing configuration.
Floor load limits with crane impact
When lowering cargo by crane, the dynamic load at touchdown can be 1.5-2x the static weight. Factor this impact load into your floor load calculations. Use timber dunnage to spread point loads from machinery feet, and always lower cargo gently — never allow free drops.
Loading Patterns Library
Optimize your container space with proven loading patterns for different cargo types
Column Stack Pattern
A simple and straightforward loading pattern with boxes stacked in vertical columns. Ideal for uniform cartons with good stacking strength.
Best For
- • Uniform, rigid cartons
- • Boxes with good stacking strength
- • When load stability is a priority
Efficiency
Pro Tips
- • Ensure columns are aligned vertically to maximize weight-bearing capacity of boxes
- • For added stability, consider plastic wrapping each column or adding corner protectors
- • Leave minimal gaps between columns to prevent shifting during transport
Interlocking Pattern
An advanced loading pattern where each layer alternates orientation, creating a more stable structure. This "brick-like" arrangement distributes weight more evenly and prevents collapse.
Best For
- • Cartons with moderate stacking strength
- • Medium to long distance shipping
- • When preventing collapse is critical
Efficiency
Pro Tips
- • Alternate the orientation of each layer by 90 degrees for maximum stability
- • Ensure boxes can support this load pattern - weaker boxes may crush despite interlocking
- • Creates better resistance against shifting during transit, reducing damage risk
Pinwheel Pattern
An efficient pattern where boxes are arranged in alternating orientations within the same layer, creating a pinwheel-like appearance. This maximizes space utilization and provides excellent stability.
Best For
- • Rectangular boxes with non-square dimensions
- • When maximum space utilization is needed
- • Shipments requiring both stability and efficiency
Efficiency
Pro Tips
- • Works best when box length is roughly twice its width (2:1 ratio)
- • Can improve stability and prevent shifting compared to simple stacking
- • For heavier goods, limit stack height and consider layer separation with slip sheets
Cargo Securing Techniques
Proper cargo securing is essential for safe and damage-free transport. Learn best practices for different cargo types and conditions.
Lashing & Tie-Down Techniques
Proper cargo lashing prevents movement during transport, reducing the risk of damage and ensuring safe delivery. Container ships can experience significant forces during transit, making secure cargo essential.
Understanding Lashing Points
Standard shipping containers come equipped with built-in lashing points in the floor, walls, and ceiling. These anchor points are designed to secure cargo with straps, ropes, or chains.
- • Floor lashing points can typically handle 2,000-5,000 kg of load
- • Wall and ceiling points usually have lower capacity (1,000-1,500 kg)
- • Always check the specific lashing point capacity in your container documentation
Effective Lashing Techniques
Diagonal Lashing
Straps run diagonally from the cargo to the lashing points, creating tension that prevents movement in multiple directions.
Loop Lashing
Straps form loops around the cargo and attach to lashing points on the same side, providing lateral stability.
Cross Lashing
Straps cross over the cargo in an X pattern, providing excellent stability against both lateral and longitudinal forces.
Direct Lashing
Straps connect directly from the cargo to the nearest lashing point, offering simple but effective restraint.
Pro Tips
- • Always use lashing points on opposite sides to create balanced tension
- • Check strap tension periodically during loading to account for settling
- • Use edge protectors where straps contact cargo edges to prevent damage
- • For heavy cargo, combine multiple lashing methods for redundancy
Essential Tie-Down Equipment
Lashing Straps
- • Breaking strength: 2,500-10,000 kg
- • Available in various lengths
- • Typically made of polyester
Tensioners & Ratchets
- • Working load limit: 500-5,000 kg
- • Look for smooth ratchet operation
- • Choose appropriate size for strap
Hooks & End Fittings
- • Claw hooks for lashing points
- • J-hooks for various attachments
- • Safety latches prevent disengagement