An open top has full walls but an open roof covered by a tarpaulin. It is a common choice for slightly tall machinery or cargo that cannot go through the doors. This guide covers actual specifications, loading and when a flat rack is the better option.
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What is an open top?
An open top container has a floor, side walls and end walls like a standard container, but a removable tarpaulin instead of a solid roof. It normally keeps end doors too, so cargo can go in through the doors or be lifted in from above.
Cargo lifted through the roof must fit the roof opening in length and width. Cargo taller than the walls can still ship under the tarpaulin, but the shipment then becomes out-of-gauge (OOG).
Open top dimensions and payload
Example specifications published by Hapag-Lloyd. Actual units vary by manufacturer, age and owner.
| Specification | 20' open top | 40' open top | 40' open top high cube |
|---|---|---|---|
| Inside length | 5.895 m | 12.029 m | 12.029 m |
| Inside width | 2.35 m | 2.35 m | 2.352 m |
| Inside height | 2.34 m | 2.344 m | 2.649 m |
| Roof opening (W × L) | 2.23 m × 5.338 m | 2.23 m × 11.552 m | 2.192 m × 11.552 m |
| Max payload | 30.05 t | 28.45 t | 28.25 t |
According to the same source, with the roof bars removed the usable inside height rises to about 2.42 m for a 40' open top and 2.72 m for a 40' open top high cube. The roof opening is about 12 to 16 cm narrower than the inside width, so measure against the opening, not the interior.
When to choose an open top
- The piece is taller than a standard door (about 2.292 m on a 40GP, 2.597 m on a 40HC) but its width fits the roof opening.
- The piece must be lifted in from above because it cannot be forklifted in.
- The cargo needs tarpaulin cover, which a flat rack cannot provide.
Open top or flat rack?
Rule of thumb: if the piece fits the roof opening and is not too heavy, an open top is usually simpler; if it is wider than the opening or heavier than the open top payload, use a flat rack; if it is longer or heavier than a 40' flat rack, ship it as breakbulk.
| Criterion | Open top | Flat rack |
|---|---|---|
| Side walls | Yes | No |
| Roof | Removable tarpaulin | None |
| Wider than the roof opening | Not possible | Possible, overhanging the sides (OOG) |
| Taller than the walls | Possible, overheight (OOG) | Possible, overheight (OOG) |
| Max payload (Hapag-Lloyd) | 28.25 t to 30.05 t | 42.1 t to 49.1 t |
Before booking an open top
- Measure the overall dimensions, including crates and protruding parts
- Compare width and length with the roof opening, not just the interior
- If the piece is taller than the walls, declare the overheight so the carrier can approve an OOG booking
- Prepare lifting points and a lashing plan inside the container
