Flat Rack, Open Top or Breakbulk? Choosing for OOG Cargo

Out-of-gauge (OOG) cargo is cargo that does not fit inside a standard general purpose container because it is too long, too wide or too high. Machinery, vehicles, boats, steel structures and industrial modules often fall into this group. This guide answers a common question: which equipment suits my cargo, and what does my forwarder need to quote it?

The short answer: if the cargo is only too high, an open top container may work. If it is too wide or too high, a flat rack is the usual choice. If it is too big or heavy for container equipment, breakbulk on a conventional or multipurpose vessel is the next option.

Open top containers

An open top has a removable roof, usually covered with a tarpaulin. It is used for:

• cargo that is taller than a standard container, such as machinery, vehicles, tyres and steel coils;
• cargo that fits in the container but must be loaded from above by crane, such as large glass sheets.

If the cargo stands above the roof line, it counts as out of gauge and the carrier will need exact dimensions.

Flat racks

A flat rack has a floor and end walls but no side walls or roof. It is mainly used for over-width and over-height cargo.

• Fixed-end flat racks suit cargo that is only over-width or over-height.
• Collapsible flat racks have end walls that fold down to form a flat platform. Several can be used together for cargo that is also over-length.
• Super racks have corner posts that extend upward to give extra height.

Platforms can also be placed below deck to carry oversized cargo that spans several container slots.

Breakbulk

When cargo is too large, too heavy or too awkward for container equipment, it can be shipped breakbulk: lifted on board on its own, using ship or shore cranes. Multipurpose and heavy lift vessels are built for this trade. Breakbulk needs more planning, but it can avoid dismantling the cargo.

What to send for a quote

The more accurate the information, the more accurate the quote. For any OOG or project shipment, prepare:

1. Dimensions of each piece: length, width and height, in centimetres, including any parts that stick out.
2. Weight of each piece, and the gross weight with any skid or cradle.
3. Drawings or photos, ideally with the centre of gravity marked.
4. Lifting and lashing points, and whether the cargo has its own lifting lugs.
5. Packing details: bare, on a skid, crated or wrapped.
6. Origin and destination addresses, not only ports, so inland transport and road permits can be checked.
7. Ready date and required delivery window.
8. Cargo description, and whether any part of the item contains fuel, batteries or other dangerous goods.

Things that change the plan

• Road permits and escorts. Oversized loads on public roads may need permits or escorts at origin and destination. Arrange these before the cargo is ready.
• Port and terminal limits. Some terminals have limits on crane capacity or on handling OOG units.
• Space on board. OOG units on flat racks can take extra space on board, which affects availability and price.
• Weather protection. Cargo on flat racks is exposed. Ask whether wrapping or a cover is needed.

Common mistakes

• Sending only the overall size, without separate dimensions for each piece.
• Leaving out protruding parts such as handles, pipes or mirrors.
• Underestimating weight, which can change the lifting plan.
• Booking the ocean leg before checking inland transport permits.

Planning project cargo? Share the dimensions, gross weight, drawings and delivery window of your project cargo with ANIL DARYA so our team can review suitable freight options. See our break bulk service or use our freight rate inquiry.

Sources (checked 7 November 2026):

• Shipping and Freight Resource, "Special Containers & its Cargoes – OOG/Reefer – A Refresher", updated 3 August 2026. https://www.shippingandfreightresource.com/special-containers/
• Shipping and Freight Resource, "5 points to consider before packing your cargo", updated 3 August 2026. https://www.shippingandfreightresource.com/points-to-consider-before-packing-your-cargo/