The open top gets proposed the moment the cargo is 30 cm too tall for a dry container. Most of the time it is the right answer — but it is not a dry container with the roof taken off. Between the roof bows and the tarp, four things change, and any one of them can stop the shipment.

What an open top actually is

  • 20'OT and 40'OT: the same footprint as a standard box, no fixed roof, and a removable tarpaulin stretched over steel roof bows
  • Internal height stays close to a standard box, around 2.35 m — the cargo still has to fit inside once it is in; what changes is the opening
  • Loading is vertical, by crane, through the top — not by forklift through the door
  • Lashing points are the floor D-rings and the side rails; the bows and the tarp carry nothing

A case from Shekou, anonymised

A Shenzhen machine builder had a skid 2.7 m high, 2.2 m wide, 5.8 m long and 19 t. It would not pass a dry container door; a flat rack had been quoted and rejected on price. The open top took the height and the width. What decided the sailing was not the box but the cranes at both ends — and the fact that a tarp makes the box weather-resistant, not waterproof.

Step 0: check the opening, not only the internal height

  • The roof opening is roughly 2.2–2.3 m wide; cargo plus lifting gear has to pass through it
  • Internal height is about 2.35 m, so allow for dunnage and lashing and plan on 2.2 m of cargo
  • Door height matters only if the unit has to be moved inside the box after the lift
  • Payload and road limits still apply: a 40'OT is not permission to load 30 t

Step 1: book the equipment, not just the space

Open tops are special equipment. Ask 7–14 days ahead in a normal market, longer before Chinese New Year and through peak season. Get the type onto the booking confirmation — 40'OT, not "40HQ, open top requested" — and have the carrier's special equipment approval in hand before the cargo leaves the factory.

Step 2: the crane is part of the routing

  • Origin: crane capacity, lifting points, spreader or slings, and whether the yard can lift at the hour you need
  • Destination: the consignee has to be able to lift it out; an open top that arrives where nobody has a crane becomes a storage bill
  • Transhipment: some terminals will not handle open tops without an approved plan

Step 3: agree the lashing plan before loading

  • Lash to floor D-rings and side rails only — never to the bows or the tarp
  • Timber dunnage under the skid spreads the load and keeps the base off the floor
  • Cross-lash at 30–60°, with the number of points calculated from the weight, not copied from the last job
  • Where the carrier requires it, a third-party survey signs off before the tarp goes back on

Step 4: the document set

  • Dimension drawing: length, width, height, weight, centre of gravity, lifting points
  • Booking confirmation showing the equipment type and any special approval
  • Lashing plan and, where required, the survey report
  • Packing list, invoice and VGM
  • Photos before loading, after lashing, with the tarp fitted, and at gate-in
  • Dangerous goods declaration if the unit carries batteries or fuel

Step 5: the loading checklist, seven steps

  1. Inspect the open top at the yard: floor, D-rings, roof bows, tarp condition — photograph all four
  2. Place the dunnage and confirm the floor is dry
  3. Lift with the agreed gear and land the unit on the centreline
  4. Secure to the floor, then cross-lash to the rails to the plan
  5. Refit the bows and the tarp; check no lashing is trapped under the tarp
  6. Record final dimensions and weight, and take the four photos
  7. Seal, gate in, and confirm the bill of lading carries the container type and the cargo dimensions

Where it usually goes wrong

  • Booked as a dry container, with the open top requested at the last minute; the tarp arrives after the cut-off and the unit is rolled
  • Tarp fitted without the bows, so water pools and the tarp tears in wind
  • Lashing taken to the rail on one side only, leaving the unit free to shift
  • Condensation ignored: machined surfaces arrive spotted, and the claim arrives with them
  • A consignee with no crane, so the box waits at destination and storage starts

An open top is a crane booking with a container attached. Send the dimensions, the weight and the lifting points before you ask for the rate; we will confirm the equipment, the approval and the lashing points in writing.