TL;DR: For voyages on ships you charter rather than own, the reporting problem is evidence, not arithmetic. An external reviewer will accept a modelled figure, but only if you can show the method, state the coverage and produce the voyage-level data underneath it. ZeroNorth's AI-enabled fuel model is DNV-verified at 93.8% accuracy, which is what allows a modelled consumption figure to stand without being re-derived.
A sustainability lead closes the financial year with a list of several hundred voyages and primary fuel data for only some of them. The rest were on chartered tonnage. Those masters report to the owner, not to the charterer, and no contract obliges them to report twice.
The arithmetic is not the hard part. The hard part is that the resulting figure has to survive an external assurance review, and the reviewer will ask where each voyage's number came from. "Estimated" is an acceptable answer. "Estimated, and we cannot show you from what" is not, and the usual remedy is a disclaimer on the face of the report about voyages that could not be covered.
So the question to put to any maritime emissions management software is not how it calculates. It is what it can evidence, voyage by voyage, when someone outside your organisation asks.
What an auditor is actually testing
An auditor is not testing your emissions total: they are testing whether you can reproduce it.
That distinction changes what good looks like. Three things get examined. Whether one method was applied consistently across comparable voyages, or whether the approach shifted depending on what data happened to be available. Whether the coverage of the reporting period is stated rather than implied, so it is clear which voyages carry primary data and which are estimated. And whether any figure in the report can be traced back to the voyage records behind it, on request, without the finance team rebuilding it in a spreadsheet.
There is a fourth failure mode that catches charterers in particular. When the same voyage exists in two systems and the two hold different values, the reviewer sees an inconsistency rather than an estimate, and an inconsistency is a finding. A single figure that flows from voyage data through to the reported total is worth more under assurance than a more precise figure that only exists in one place.
What the software has to do when the master does not report to you
For chartered voyages, maritime emissions management software has to produce a figure from incomplete inputs and record exactly which inputs it used for each one.
Three capabilities do that work, and they are worth testing directly in any evaluation.
A coverage register maintained through the period, not reconstructed at the end. The system should be able to tell you at any point which voyages in the current period have primary data, which are modelled, and which are still missing a counterparty contact or a discharge confirmation. Reporting teams usually discover their coverage gap in the closing fortnight, when there is no time left to chase it. Knowing in week six which twenty voyages are at risk is the difference between chasing them and disclaiming them.
Vessel-specific modelled consumption rather than a fleet average. Position data alone tells you where a ship went and roughly how fast. Turning that into fuel burned requires a model of that particular vessel, and the quality of the model is what separates an estimate a reviewer will accept from one they will challenge. A fleet-average factor applied to a chartered-in handysize is not evidence, it is a placeholder.
Voyage-level export, not just a dashboard total. Assurance work happens in the reviewer's own files. If the platform can only show a number on screen, someone has to transcribe it, and the transcription becomes the thing being audited. ZeroNorth maritime emissions management software holds owned and chartered voyages in the same dataset and exports at voyage level, so the total in the report and the records supporting it come from one place. The mechanics of how individual voyage figures are derived and checked are covered in more detail in how emissions figures are verified.
Which method holds up for chartered tonnage
The method you choose decides what you are able to state in the report, not merely how accurate the number is.
The third row is the only one that lets you answer the two questions assurance always asks, which are what method you used and how much of the period it covers.
Why independent verification of the model matters more than the model
A modelled figure carries only as much weight as the verification behind the model.
This is where a vendor's own accuracy benchmark stops being useful. What a reviewer, a charterer or a financier needs is a number that someone outside the commercial relationship has tested. ZeroNorth's AI-enabled fuel model has been verified by DNV at 93.8% accuracy, set out in the DNV-verified fuel model announcement, and it is built on more than 2.7 million voyages and 5.2 million MT of CO2 tracked across the platform. Verification is what converts a modelled consumption figure from an internal working estimate into something that can be presented without being re-derived.
The bottom line
Choose on what the system can evidence about a voyage, not on how accurate it claims its estimates are.
The vendor-neutral version of that question is simple enough to ask anyone: for a voyage where the master never reported to us, show me what the report would say, where the number came from, and what you would hand my auditor.
For ZeroNorth the answer is four specifics. Owned and chartered voyages sit in one dataset rather than two that have to be reconciled. Coverage is visible through the period, so the gap is a work item in week six instead of a disclaimer in week twelve. Consumption is modelled per vessel against a model DNV has verified at 93.8% accuracy. And the export is at voyage level, so the reviewer traces the total back to the records themselves. Allocating those figures across counterparties and cargoes is a related problem, covered in emissions allocation and tracking.
If your reporting period is closing now, see how Emission Analytics handles chartered tonnage, review pricing, or book a demo and bring the voyages you cannot currently evidence.
