Laytime revisions: explain why the result changed

Key takeaways

• Preserve the account previously circulated and its assumptions.
• Classify each change as factual, interpretive or mathematical.
• Recalculate the affected result and explain the difference.
• Keep unresolved alternatives separate from an agreed correction.
• Review downstream consequences rather than assuming the change is confined to one row.

Identify the level at which the revision occurs

BIMCO's laytime and demurrage course treats commencement, stoppage and termination as distinct topics. Those distinctions are useful context for a revision review. Check the current text of the charter and obtain advice before changing the contractual treatment applied to an event.

A factual revision changes the event evidence: for example, a corrected start or end of an interruption. An interpretive revision changes how established facts are treated under the agreement. A mathematical revision corrects the implementation of an already stated assumption. These changes should not all be described as “updated laytime.”

The classification matters commercially. A counterparty may accept an arithmetic correction while disputing a new interpretation. If the revised file combines both without explanation, a discussion about a simple error can become confused with a substantive claim disagreement.

Record the reason for the change before modifying the account. This creates a clear link between the new evidence or decision and the affected calculation.

Preserve the comparison basis

Retain the account as previously issued, not just a working file that has continued to change. Identify its relevant inputs, counting assumptions and result. The revised account should have its own status and should not overwrite the historical position.

Use the same scope when comparing the versions. If the earlier account covers one port and the new one covers additional operations, the total difference cannot be explained solely by a corrected interruption. Separate the scope expansion from the revision to the original component.

Likewise, keep unit conventions consistent. A comparison between hours in one file and decimal days in another needs a clear conversion. Formatting changes should not obscure a material difference or create the appearance of one where the underlying value is unchanged.

The comparison should identify every material assumption that changed. A revision note that mentions a new event time but omits a changed counting rule does not explain the new result adequately.

Worked fictional revision: a shorter excluded interval

The following ILLUSTRATIVE example assumes an agreed counting method solely to demonstrate arithmetic. The elapsed review window is 50 hours, allowed time is 40 hours, and the original account excludes 6 hours. New evidence is assumed to establish that the same agreed exclusion lasted only 3 hours. No other input or rule changes.

The revised counted time rises by 3 hours, and the excess also rises by 3 hours. The reconciliation is complete because the change in the result follows from the only changed input. This example calculates excess time only; it does not establish a demurrage entitlement or apply a monetary rate.

In a live account, the reviewer must first establish whether the factual correction and counting assumption are justified. Correct subtraction cannot answer that question. The purpose of the worked example is to show how an accepted input change should remain traceable through the result.

Distinguish a correction from an alternative position

If the parties disagree about the revised input or rule, present the new result as a stated position or alternative scenario, not as an agreed correction. The label should reflect the actual status of the issue.

A factual correction may be supported by a revised source record. An alternative interpretation may depend on advice about the charter. Keep those supporting materials distinct so the counterparty can identify what it is being asked to accept.

Where several disputed issues exist, isolate their effects where practical. A single aggregate difference can hide the contribution of each assumption. The principal needs to understand which issue drives the commercial exposure and which changes are merely presentational.

Do not use alternative scenarios to imply that every outcome is equally plausible. State the basis and evidential limitations of each. Appropriate legal and commercial reviewers can then assess which position should be advanced or used for an internal decision.

Check consequences beyond the edited row

Changing an interruption can affect more than the displayed duration of that interruption. It may alter a cumulative total or the point at which an allowance is exhausted under the assumed method. The reviewer should identify those dependencies rather than stop after correcting the local arithmetic.

This does not mean applying a universal rule to all later periods. The treatment of time after a relevant threshold depends on the actual charter. If the revision changes which contractual regime is being considered, obtain appropriate review of the subsequent entries.

Check any money calculation separately. The time result, contractual rate, unit conversion and account treatment each require validation. A correct change in hours can still produce an incorrect amount if the financial formula uses an inconsistent basis.

Also review the narrative. A cover email may still describe the original cause, period or claimed basis after the spreadsheet has changed. The circulated account should tell one coherent story about the factual inputs, adopted interpretation and arithmetic.

Release the revised account with a concise reconciliation

The release note should state what changed, why, the effect on the result and whether the change is agreed or disputed. Attach or identify the relevant supporting evidence without overwhelming the recipient with unrelated voyage records.

If the revised account supersedes an earlier demand or provisional statement, describe that relationship accurately and obtain the necessary authority. Do not assume that a new attachment silently withdraws or settles an earlier position. The legal and commercial effect of the communication deserves appropriate review.

The recipient should be able to reproduce the material difference without guessing. That is the practical test of a useful revision. A spreadsheet can be technically detailed yet fail this test if its central assumption is buried in an unlabelled cell or unexplained override.

Once issued, preserve the revised version and its support as a new account event. Future corrections can then be compared against a stable record rather than a file whose history depends on individual memory.

Common mistakes

The main mistake is presenting a new total without explaining the changed premise. Another is describing a disputed interpretation as a factual correction. Classify the change before asking the counterparty to accept the result.

Avoid checking only the edited row while leaving dependent periods or money formulas untouched. Do not compare different account scopes as though they were identical. Finally, reconcile the cover narrative with the spreadsheet; inconsistent explanations can obscure an otherwise correct calculation.

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