Out-of-Gauge (OOG) Container Shipping: Flat Rack, Open Top and Platform
Cargo that overhangs the container: dimension declaration, equipment choice, line approval, lashing and on-deck stowage planned before the booking is made.
Out-of-gauge (OOG) cargo is cargo that does not fit inside the dimensions of a standard closed container: it is too high, too wide, too long, or all three. It still travels in the container system, on specialised equipment such as open-top containers, flat racks and platforms, but it needs more planning than a standard box. The carrier has to approve the dimensions in advance, because the unit can take up more than its own slot on the ship.
What is out-of-gauge cargo?
Cargo is out of gauge when any part of it extends beyond the internal dimensions of the container it is loaded on. Over-height cargo rises above the top of the container, over-width cargo extends beyond the sides, and over-length cargo extends beyond the ends. Cargo that merely weighs more than a standard container allows is a separate case, dealt with as overweight or heavy cargo. Cargo that fits inside the container, even when it is heavy, is in gauge. The distinction matters because out-of-gauge cargo needs different equipment, a line approval, a stowage position on the ship that can accommodate it and, in most cases, stowage on deck.
Which equipment is used?
Three equipment types are used, and the choice follows the shape of the cargo. An open-top container has walls and a floor but a removable roof, so tall cargo can be loaded from above by crane and can stand above the top rim; it is the usual choice for over-height pieces. A flat rack has a floor and end walls, which on some types fold down, but no side walls and no roof, so cargo can overhang at the sides and above; it suits wide and heavy pieces such as machinery, pipes and blocks. A platform is a floor without end walls, used for the longest and the widest loads. The internal dimensions and maximum payloads of each type vary with the type and the owner, so the line confirms them for the booking; see also the container capacity tool for standard boxes.
How are OOG dimensions measured and declared?
The measurement is taken at the extreme points of the cargo as it will actually be loaded, including its securing and any protruding parts, and compared with the footprint of the container: how far it extends beyond the front, the back, each side and the top. The declaration to the line at booking includes these overhangs, the gross weight, the centre of gravity, the lifting points and a drawing. The line uses it to plan the stowage and to decide whether it can accept the cargo at all. An undeclared or understated dimension can lead to refusal at the terminal, extra charges, delay and, in the worst case, a safety problem on the ship; for that reason we ask for exact figures, not estimates.
- Overhang beyond the front, the back, each side and the top, measured at the extreme points.
- Gross weight and centre of gravity, with the lifting points.
- A drawing or photograph of the cargo as it will be loaded.
- The loading and discharge ports and the dates the cargo will be ready.
Why does OOG cost more and need more planning?
An out-of-gauge unit often blocks the neighbouring slots on the ship, because the overhang cannot be stacked against or under another container, and the line prices the lost space. It usually travels on deck, in a position chosen for the shape of the cargo, and special lifting and handling may be needed at the terminals. Only some vessels, lines and ports accept certain dimensions, and approval can take time. The charge is set by each line and shows up in the quote as an OOG surcharge or as the price of the slots used; ask for it to be itemised, together with the terminal handling and the other local charges, so that you can compare offers on the same basis.
How is OOG cargo loaded and secured?
Loading is by crane or, for low and wheeled cargo, by ramp or forklift, at the shipper's premises or at the terminal. The cargo is secured with chains, wires and turnbuckles to rated lashing points, with dunnage to spread the load and protect surfaces, according to a securing plan that takes the movements of the ship into account. Tarpaulins protect against weather but should not be assumed to be watertight, so sensitive cargo needs additional protection. The loaded unit must stay within the equipment's payload, and its verified gross mass has to be declared before loading; see VGM. The pre-carriage by truck of an oversized unit is itself an abnormal-load move that needs permits; see project cargo for the route and permit side.
OOG container or break-bulk vessel?
The decision depends on the size, the weight and the number of pieces, and on the ports and the schedule. An OOG container suits a single piece or a few pieces that stay within what the line accepts and that can use a regular liner schedule. When the pieces are larger or heavier than the lines accept, when there are many of them to move together, or when no suitable liner service exists, break-bulk on a conventional vessel or a dedicated charter becomes the better answer; see vessel charter. In some projects both are combined: the largest pieces go on the vessel and the smaller ones on flat racks. We compare the options on total cost and total risk, not on the freight line alone; see also sea freight.
Equipment for out-of-gauge cargo
| Equipment |
Typical use |
Limits to check |
| Open-top container |
Over-height cargo loaded from above by crane |
Roof or tarpaulin arrangement, maximum height and payload for the type |
| Flat rack (fixed or collapsible end walls) |
Over-width and over-length cargo, heavy machinery, pipes and blocks |
Payload, securing points, overhang accepted by the line |
| Platform (no end walls) |
Very long or very wide loads |
Availability, securing points, port and ship limits |
| Break-bulk on a conventional vessel |
Pieces beyond what liner services accept, or many pieces |
Crane capacity at both ports and the stowage plan |
Documents used in this shipment
- Cargo data sheet and drawing — dimensions, overhang, gross weight, centre of gravity and lifting points
- OOG booking request and line approval — the carrier's acceptance of the dimensions and the stowage position
- Lashing and securing plan — the securing points, equipment and calculation
- Verified gross mass (VGM) declaration — required before the loaded unit is accepted for loading
- Bill of lading — the contract of carriage and, in its original form, the document of title
- Commercial invoice and packing list — the source of value, number of packages, weights and HS code information
- Export declaration — the principal document of the customs exit procedure
- Abnormal-load permits — for the road legs of an oversized unit
- Cargo insurance policy — covering on-deck stowage
Frequently asked questions
What happens if the dimensions are not declared correctly?
The line can refuse the cargo at the terminal, charge for the extra space actually used, or hold the unit until a suitable stowage position is found. An understated overhang can also be a safety problem on the ship. The dimensions must therefore be measured as the cargo will actually be loaded, with all protruding parts.
Can OOG cargo be shipped as LCL?
In practice, no. Out-of-gauge cargo needs its own unit and its own line approval, so it is booked as a whole unit, not consolidated with other cargo.
Is OOG cargo insured differently?
It should be checked. Out-of-gauge cargo usually travels on deck, so the cargo insurance policy has to cover on-deck stowage, and for high-value cargo the insurer can ask for a survey or a lashing plan. Discuss it at the start of the booking.
Who pays for the lost slots?
The cost of the space that the unit blocks is passed on by the line, usually as an OOG surcharge or in the freight price. Ask for it to be itemised in the quote so that it can be compared between offers.
What information do you need for an OOG quote?
The overhang beyond the container at the front, the back, each side and the top, the gross weight, the centre of gravity, a drawing or photographs, the number of pieces, the loading and discharge ports and the ready date.