OOG Cargo
Is Your Cargo Out of Gauge?
Enter your cargo dimensions and weight to instantly see whether it exceeds standard container limits, which OOG equipment it requires, and what to expect.
Standard container internal limits
| Container | Length | Width | Height | Max payload |
|---|---|---|---|---|
| 20ft Standard | 5.89 m | 2.35 m | 2.39 m | 21.8 MT |
| 40ft Standard | 12.03 m | 2.35 m | 2.39 m | 26.68 MT |
| 40ft HC | 12.03 m | 2.35 m | 2.69 m | 26.33 MT |
Enter cargo dimensions above to see OOG assessment.
OOG Equipment
Equipment Types for Out of Gauge Cargo
Choosing the right equipment is the first and most critical decision in OOG shipping. Each type has different dimensional capabilities, lashing points, and operational requirements.
Open Top 20ft
Platform: 5.89m × 2.35m × open
Payload: ≤ 28,000 kg
Standard 20ft footprint with removable roof bows and a tarpaulin cover instead of a solid roof. Ideal for overheight cargo that can be crane-loaded from above. Commonly used for machinery, vehicles, coils, and stone blocks.
✦ Overheight cargo up to ~3.5m, crane-loadable
Open Top 40ft
Platform: 12.03m × 2.35m × open
Payload: ≤ 26,500 kg
Same as 20ft open top but with 40ft length. The most common open top used for industrial machinery, large spools, and oversized equipment that is too tall but within width limits.
✦ Long overheight cargo, loaded by crane or tilt-bed
Flat Rack 20ft (Fixed End)
Platform: 5.64m × 2.23m platform
Payload: ≤ 34,000 kg
A flat platform with fixed rigid end walls. Cargo can overhang the sides and is secured with lashing chains and straps to the built-in lashing rings. End walls provide structural rigidity and additional lashing points.
✦ Heavy machinery, steel structures, industrial equipment
Flat Rack 40ft (Collapsible End)
Platform: 12.12m × 2.25m platform
Payload: ≤ 40,000 kg
The most versatile OOG container. End walls fold flat for easy loading and stacking of empty units. Higher payload capacity than fixed-end flat racks. Widely available across major trade lanes.
✦ Most overwidth/overlength cargo — most commonly available
Platform / Bolster
Platform: Variable
Payload: Up to 60,000 kg+
A flat steel platform with no walls or roof. Maximum freedom for very large cargo. Requires custom lashing design and engineering approval. Used for transformers, pressure vessels, large industrial components.
✦ Extremely large or heavy cargo, transformers, pressure vessels
Costs & Surcharges
What Does OOG Shipping Actually Cost?
OOG freight is significantly more expensive than standard containerized cargo. Here's every cost component you need to budget for.
OOG / Special Equipment Surcharge
A flat surcharge applied by the carrier for booking OOG equipment. Higher for extreme dimensions, rarer equipment types, or less-served trade lanes. Always quoted per Bill of Lading, not per container.
Flat Rack / Open Top Freight Rate Premium
The base ocean freight rate itself is higher for flat rack and open top equipment, reflecting the lower equipment availability and the displaced stacking capacity on the vessel.
Lashing & Securing Materials
Lashing chains, tensioners, wooden blocking, dunnage bags, and tarpaulin (for flat rack cargo exposed to weather). Often supplied by the freight forwarder's local agent or surveyor.
Pre-Shipment Survey / Cargo Inspection
Many carriers and ports require a survey report confirming the cargo dimensions, weight, and securing plan before acceptance. Required by some insurance policies and mandatory for certain cargo types.
Port Handling (Terminal Surcharge)
OOG cargo requires special handling equipment at origin and destination terminals — heavy cranes, reach stackers, or specialised spreaders. Terminals charge accordingly.
Inland Transport Permits
Oversize loads on the road require movement permits from transport authorities, and sometimes pilot vehicles, police escorts, or route surveys. Highly variable by country and cargo dimensions.
Lashing & Securing
How OOG Cargo Must Be Secured
Improper securing of OOG cargo is one of the leading causes of cargo damage and vessel incidents. These are the rules — not guidelines.
The IMO/ILO/UNECE CTU Code
The Code of Practice for Packing of Cargo Transport Units (CTU Code) is the international standard governing how cargo must be secured in containers and on flat racks. It is referenced by most major carriers in their booking terms and is the baseline for any OOG securing plan.
Core securing principles
Blocking
Wooden blocks or steel wedges placed against the cargo to prevent longitudinal and lateral movement. Must be able to withstand the cargo weight under dynamic forces (typically 0.8g longitudinally, 0.5g laterally).
Bracing
Structural members (timber, steel) installed between the cargo and the flat rack end walls to absorb and distribute dynamic loads during sea passage.
Lashing
Chains, wire ropes, or webbing straps attached to the cargo and to the flat rack lashing rings. The aggregate lashing capacity must exceed the calculated securing forces. Chains are preferred for heavy cargo.
Dunnage
Material placed between the cargo and the flat rack deck to prevent sliding, distribute the load, and protect both the cargo and the equipment surface.
Flat rack lashing rings
Standard 20ft flat racks have 8–12 lashing rings rated at 3,000–5,000 kg per ring. 40ft flat racks typically have 14–20 rings. The securing plan must use enough rings to distribute load evenly — never concentrate all lashing on two rings.
Weather protection on flat racks
Cargo on flat racks is exposed to weather during transit unless covered with tarpaulin. Non-waterproof machinery, electronics, or sensitive components must be wrapped in waterproof sheeting before tarpaulin is applied. Request climate-controlled stowage for sensitive cargo.
Cargo securing survey
For high-value, heavy, or unusual OOG cargo, commission an independent marine surveyor to inspect and certify the securing arrangement before departure. The survey report protects your cargo insurance claim and satisfies carrier requirements.
Documentation
Documentation Required for OOG Cargo
OOG shipments require significantly more documentation than standard containers. Missing a single document can result in cargo being refused at the terminal.
OOG Pre-Booking Approval
Before a carrier will accept an OOG booking, you must submit the cargo dimensions (L×W×H), gross weight, and a sketch or photo to the carrier's special cargo desk. The carrier checks vessel stowage feasibility and issues an approval with conditions.
Cargo Sketch / Technical Drawing
A dimensioned drawing showing the cargo in its shipping configuration, including the highest point, widest point, and position of the centre of gravity (COG). Must include all protrusions, lifting lugs, and attachments.
Weight Certificate
For cargo over 1,000 kg, a weigh-bridge or calibrated scale certificate confirming the verified gross mass (VGM). Required by SOLAS regulation and for flat rack selection — overloading a flat rack is a serious safety incident.
Cargo Securing Plan
A documented plan specifying the lashing points used, lashing type and capacity, blocking arrangement, and the calculated securing forces. Required by most major carriers for heavy or unusual OOG cargo.
Bill of Lading (OOG Clausing)
The B/L must be claused with the OOG dimensions and any overhang. Carriers add notations such as 'Flat Rack', 'Open Top', overhang cm, and 'Shipper's Load, Count and Seal'. Verify all dimensions on the draft B/L before release.
Insurance Certificate (OOG Extension)
Standard cargo insurance may not automatically cover OOG shipments on flat racks. Ensure your marine cargo policy specifically covers open/flat rack stowage, weather exposure, and any overweight or oversize conditions.
OOG Tips
Six Things to Know Before Shipping OOG
Book early — OOG equipment is scarce
Flat racks and open tops represent less than 3% of the global container fleet. On busy trade lanes (Asia–Europe, transpacific), equipment can be booked out weeks in advance. Submit your pre-approval request at least 3–4 weeks before cargo ready date.
Measure twice, declare exactly
Carriers set stowage on the vessel based on your declared dimensions. If your cargo arrives larger than declared, it may be refused at the terminal — at your cost. Measure with protrusions, lugs, protective packaging, and lifting eyes included.
Know your overhang limits by port
Most ports and carriers allow a maximum of 30–40cm overhang on each side of a flat rack before additional surcharges, stowage restrictions, or outright refusal apply. Some ports prohibit overwidth flat racks entirely on certain berths.
COG matters as much as dimensions
A high centre of gravity (COG) makes cargo unstable under vessel motion. If your COG is above deck level of the flat rack, your carrier or surveyor may require additional securing measures or restrict the cargo to specific vessel stowage positions.
Budget for inland oversize permits early
Oversize transport permits for road legs can take days to weeks to obtain in some countries. The truck, trailer, and route must often be pre-approved by transport authorities. This is frequently the longest lead-time item in an OOG shipment.
Use a specialist freight forwarder
Not all freight forwarders handle OOG cargo regularly. Use a forwarder with a dedicated project cargo or heavy lift desk — they have carrier relationships, know the port restrictions, and understand the lashing and documentation requirements.
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