Insight · Container guide · OOG
An open top container is a standard box without a fixed roof. You load it from above by crane, cover it with a tarpaulin, and ship cargo that is too tall for a door.
Written by our operations team in Ho Chi Minh City. · Jump to dimensions
Short answer: use an open top container when your cargo is too tall to go through the door or must be lifted in from above, but is not wider than the box. If it is also too wide, you need a flat rack. If it sticks out above the top, it becomes over-height (OOG) cargo and needs carrier approval before booking.
An open top container (OT) has the same steel walls, floor and doors as a dry container. The difference is the roof. Instead of a fixed steel roof, it has removable roof bows and a heavy-duty tarpaulin that is tied down along the top rails.
Most units also have a swing door header. The steel beam above the doors can be swung out of the way, so a tall item can be pushed or lifted in through the door end as well as from the top.
Typical cargo for an open top container:
Sizes vary slightly between carriers and container builders, so treat the table as typical values and check the spec sheet of the carrier you book with. Payload in particular differs from box to box.
| Typical value | 20′ OT (22U1) | 40′ OT (42U1) |
|---|---|---|
| Internal length | about 5.89 m | about 12.03 m |
| Internal width | about 2.35 m | about 2.35 m |
| Internal height | about 2.35 m | about 2.35 m |
| Door opening (W × H) | about 2.34 × 2.28 m | about 2.34 × 2.28 m |
| Roof opening (L × W) | about 5.4 × 2.2 m | about 11.8 × 2.2 m |
| Max gross weight | 30,480 kg | 30,480–32,500 kg |
| Tare | about 2,200–2,400 kg | about 3,750–4,000 kg |
| Payload | about 28,000 kg | about 26,500–28,750 kg |
| Volume | about 32 m³ | about 65–66 m³ |
The photo at the top of this page shows a real example: the data plate on that 40′ open top container reads max gross 32,500 kg, tare 3,750 kg, payload 28,750 kg and 65.9 m³. Always read the plate on the box you receive, not the brochure.
The three boxes solve different problems. Choose by the dimension that does not fit, not by the cargo name.
| Your cargo is… | Best box | Why |
|---|---|---|
| Within 2.3 m wide and 2.2 m high, can go through the door | Standard dry container | Cheapest, no special equipment |
| Too tall for the door, or must be lifted in from above, but within the width | Open top container | Walls protect the cargo; tarpaulin keeps rain out |
| Too wide for any container, or wider and taller | Flat rack | No side walls, so over-width is possible |
| Too large or heavy for any container | Breakbulk or Ro-Ro | Loaded as a single piece, in the hold or on deck |
For the flat rack side of the decision, see our flat rack container dimensions guide. For units that fit neither box, see breakbulk and heavy lift in Vietnam.
If the cargo rises above the top rails, the box is over-height. It is then out-of-gauge (OOG) cargo, and three things change.
On the road the limit is lower than many shippers expect. In Vietnam a container vehicle needs an oversize permit when its total height passes 4.35 m. A standard 8’6″ box on a normal chassis already stands at about 4 m, so cargo sticking out more than roughly 30 cm usually needs a permit, a lowbed, or both. Our project cargo in Vietnam page explains the permit rules and lead times.
Crane loading is the main reason to choose an open top. The steps we follow on a typical job:
The roof bows matter more than they look. They give the side walls some of their stiffness, so we refit them after loading whenever the cargo height allows.
Add the port and the delivery site and we include the trucking plan and net rate in the same reply.
The tarpaulin is part of the container, not a free extra. It is threaded through eyelets and tied along the top rails, and on export the customs seal often goes on the tarpaulin cable as well as the doors. A torn or badly tied tarpaulin lets water in and can be a reason for a carrier to refuse the box.
Inside the box, the cargo must not move in any direction. We use:
Our crew issues a lashing certificate for the cargo we secure. Carriers and surveyors ask for it on heavy or OOG units, and it gives your customer a record of how the cargo left.
Open tops move through most container terminals in the south, as well as Hai Phong in the north. A few recent jobs from our files:
| Date | Cargo and route | Note |
|---|---|---|
| Aug 2025 | Boiler components, 2 × 40′ OT | Parts included a heat exchanger |
| Nov 2025 | 5 × 20′ OT, Vung Tau → Dong Xuyen industrial zone | Five boxes moved as one lot |
| Nov 2025 | 2 × 40′ OT + 2 × 40′ flat rack, Bau Bang → Cat Lai for export | Machinery lashed inside the boxes |
| Jun 2026 | 40′ OT + 40′ flat rack, Hai Phong port → local yard | Crane loading at the yard |
| Jul 2026 | 6 cable reels, Cat Lai → Khanh Hoa | Reels moved onto two lowbeds for the road leg |
Two lessons repeat on these jobs. First, a heavy 20′ open top is often a road problem rather than a sea problem, so the truck must be chosen before the box. Second, empty OT units can be scarce at short notice in Vietnam, so book the equipment early and confirm the pick-up depot.
Rules for container weight are set at sea by IMO (SOLAS VGM requirements); the verified gross mass of your container must be declared before loading on the vessel.
Flat rack and open top handling, carrier approval and pick-up at Vietnamese terminals.
OOG cargo →Tony Tuan, CEO: WhatsApp +84 909 411 668 · ceo@projectshipping.vn
Nura Tu, Overseas Department: WhatsApp +84 906 770 650 · overseas@projectshipping.vn
Calling from Vietnam: 0909 411 668
Last updated: October 2026 · By Tony Tuan, CEO, Project Shipping
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