Reefer-related issues account for 37% of all cargo claims handled by claims specialist Marlin Blue since the pandemic. Britannia P&I, an International Group protection and indemnity club, opened more than 250 refrigerated cargo claims files in a two-year period, totalling over USD 6 million; individual cases cited in that guidance include claims of USD 58,000 and USD 550,000.
Most shippers moving temperature-controlled cargo respond the obvious way: they put their own data logger in the container. It costs little, it produces a temperature curve, and it feels like insurance.
The record that carries the weight
Modern refrigerated containers generally carry an integral data logger tied to the refrigeration unit's microprocessor, and it is a more substantial instrument than many shippers assume. Britannia's guidance describes such loggers recording "power on and off dates and times, PTI information, alarms activated, temperature, humidity, air exchange rate, carbon dioxide" — an operational history of the machine, not a single temperature line. Capability varies by controller model and age.
That download tends to sit at the centre of the file. Marlin Blue lists "Microprocessor Downloads from the Refrigerated Container" first among the monitoring records assembled in a reefer claim, alongside Partlow charts, Equipment Interchange Receipts and pre-trip inspection results. Britannia's guidance also advises that reefer function and temperature be checked every six hours, with delivery and return air temperatures recorded each time.
Where that is followed, a carrier arriving at a dispute holds a machine record, a periodic manual log, a pre-trip test certificate and an equipment handover trail. The shipper, in many cases, holds a temperature curve from a device whose position nobody wrote down.
The placement objection
Britannia's cargo claims guidance advises members that data from shipper-placed loggers should not be accepted as evidence of product abuse while cargo is in the carrier's care, on the grounds that what such a device records varies according to where it sat within the stow. Whether a tribunal admits or discounts that evidence is a matter for the governing law and forum — but where the objection is raised, it shapes how a claim is negotiated long before a hearing.
Cargo claims counsel makes a parallel argument. Weber Gallagher's analysis of refrigerated cargo claims describes the reefer's own logger as offering objective evidence of transport conditions, and recommends it govern where the two disagree — because cargo condition is shaped by stuffing temperature, product age, packaging and loading method, none of which the carrier controls.
The objection is not that the logger drifted or that its calibration lapsed. It is narrower and harder to rebut: a temperature reading without a documented position within the stow cannot be attributed to a cause. Warm air pooling at a door-end pallet, a blocked return air path, a unit cycling normally while one corner of the load sits outside the airflow — these produce different readings at different points in the same container, and a lone number cannot distinguish between them.
Two different questions, two different answers
Shippers responding to this often reach for a tracker with more channels, assuming better instrumentation answers the objection. It answers half of it, and it is worth being precise about which half.
Where was the cargo, and in whose custody? This is a hardware question. A device logging position alongside condition data places the reading on a route and a timeline without depending on anyone's recollection. It cannot by itself establish legal custody — that still requires interchange receipts, gate records and bills of lading — but it narrows a dispute from "somewhere on a three-week voyage" to a specific leg, which is often what determines who answers the claim.
Where was the sensor inside the container? A typical cargo tracker cannot answer this. GNSS, Wi-Fi and cell-based positioning locate the container, not the device within the load, and none of them report which pallet a logger was strapped to or how far it sat from the return air path. Barcode or RFID workflows binding a device ID to a stow position can capture it, but only because a person recorded something at stuffing. Absent that step, the fact does not exist in any system, and any vendor implying otherwise is overselling.
Misreading the distinction is expensive: it leads shippers to buy their way around a problem a written procedure solves better and more cheaply.
What stronger instrumentation actually contributes
Within the half it does address, the useful capabilities are narrower than a datasheet suggests.
One time base across every channel. If temperature, position and event data are timestamped against separate clocks, the offsets become an argument in themselves. A single synchronised time base allows an excursion, a door event and a location to be shown as concurrent rather than reconciled after the fact.
Corroborating channels. A rise in ambient light inside a closed container is consistent with a door opening; a shock event is consistent with handling. Neither proves its cause alone, and each has alternative explanations. Their value is corroborative: together they turn "the temperature rose" into a sequence of events that can be tested against the carrier's own records.
Logging through the intervals the machine record does not cover. Containers spend real time unplugged. Identec Solutions reports that reefer insulation can hold internal cargo temperatures within 1–2 °C of protocol temperature through disconnection periods of one to six hours in transport — behaviour that depends heavily on ambient temperature, cargo thermal mass and insulation condition, and not a figure to rely on as a general rule. What matters evidentially is that terminal transfers, drayage between gensets, waiting time before plug-in, and the periods before stuffing and after stripping are poorly covered by the reefer's record, since how much a controller retains while disconnected varies with its recorder and backup-power configuration. A device that buffers to internal memory out of coverage and forwards on reconnection captures intervals in which custody may well be disputed.
Records that read the same way twice. Each entry carrying device identity, configuration and firmware version, exported in a documented format, raw file preserved unedited. Calibration certificates, serial numbers and an account of who retrieved the data belong in the same file — evidence that cannot be authenticated is discounted regardless of what it shows.
Framed this way, evaluating a cold chain cargo tracker becomes a question about record structure rather than sensor count. The questions worth putting to any supplier are the same: time base, buffering, export format, and whether data lands in a system the shipper controls.
The procedural half
The placement objection is answered by documentation, and documentation is a process cost rather than a capital one.
Placement should be specified and identical on every shipment: same position relative to the doors, same height in the stack, same relationship to the return air path — photographed at stuffing with the container number visible. Pulp temperature at stuffing should be logged independently, because not every temperature claim originates in transit. Britannia lists cargo stuffed at incorrect temperatures and wrong set-point settings among the causes of temperature abuse, alongside container malfunction, power loss and voyage delays.
This is not free. It requires a written stuffing SOP, training, spot audits and retention discipline — real overhead on people who are already busy. What it buys is that "where was your logger" stops being an open question and becomes a documented, repeatable fact.
A pre-shipment checklist
For shippers reviewing their own position before the next claim:
- Written placement SOP, position fixed relative to doors and return air path
- Photograph at stuffing showing device position and container number
- Pulp temperature at stuffing recorded independently of the logger
- Calibration certificate current, serial number recorded against the shipment
- All channels on one synchronised time base; export format documented
- Offline buffering confirmed, so coverage gaps do not become record gaps
- Raw data file preserved unaltered, with retrieval logged
- Carrier's reefer download requested early, while it is still routinely available
- Data in a system the shipper controls, or contractual export and retention rights where a vendor platform is used
Evidentiary treatment varies by contract, governing law and forum, and none of this substitutes for advice on a specific claim.
The takeaway
The carrier's reefer download will keep carrying weight, and reasonably so — it is equipment-generated, more comprehensive than a single temperature line, and tied to machinery the carrier is accountable for.
A shipper's record does not need to displace it. It needs to survive the objection put to it: that a reading without a documented position proves little about custody. Half of that is an architecture problem and half a procedure problem, and the procedural half is both cheaper and more often neglected.
Neither can be fixed after the claim is filed.
Sources
Refrigerated (reefer) container cargo care & claims — Britannia P&I (britanniapandi.com/2022/04/refrigerated-container-cargo-claims/)
Reefer Cargo Claims: what claims handlers need to know — Marlin Blue (marlinblue.com/reefer-cargo-claims/)
Reefer Madness: Handling Refrigerated Cargo Claims — Weber Gallagher (wglaw.com/news/reefer-madness-handling-refrigerated-cargo-claims/)
101 Reefer plugs — Identec Solutions (identecsolutions.com/news/101-reefer-plugs)
