In bulk shipping, time is the commodity that sits underneath every other commodity. When a vessel loads iron ore, crude oil, or grain, the clock is running, and the financial consequences of that clock are determined long before the vessel arrives at port.
Demurrage is the mechanism that translates lost time into a number on an invoice. Understanding how that number is derived, where it is disputed, and how it can be reduced is foundational knowledge for anyone operating in the freight, chartering, or logistics chain.
This guide covers the full picture: what demurrage is, how laytime works, the charter party clauses that govern both, a worked calculation, and the process for managing claims and disputes.
Table of Contents
What is Demurrage?
Demurrage is compensation paid by the charterer to the shipowner when a vessel is detained at port beyond the laytime allowed under the charter party.
It is not a penalty. Legally, demurrage is classified as liquidated damages — a pre-agreed rate that compensates the owner for the loss of the vessel’s earning capacity during time the vessel cannot be employed elsewhere. The rate is fixed at the time of fixture, expressed as a daily figure (or pro-rated for fractions of a day), and applies automatically once the laytime allowance is exhausted.
The principle is straightforward. The shipowner has contracted to make their vessel available for a cargo operation. The charterer has been given a defined amount of time to complete that operation. If they use more time than allowed, demurrage is the cost.
What makes it commercially significant is the scale. A Capesize bulk carrier on demurrage at $25,000 per day, detained for five days over laytime, generates a $125,000 claim from a single port call. Multiply that across a fleet or a trading book, and demurrage becomes a material line in the P&L.
Understanding Laytime
Laytime is the period of time allowed to the charterer under the charter party to load or discharge the cargo. Demurrage begins the moment that budget runs out.
Every demurrage calculation starts with the same question: when did laytime commence, and how much was allowed?
How Laytime Is Expressed
Charter parties express laytime in several ways:
Fixed time: A defined number of days or hours. “Laytime shall be 4 weather working days.” Simple to calculate; the allowance is a fixed number.
By rate: Laytime is calculated by dividing the cargo quantity by the agreed loading or discharging rate. A cargo of 60,000 metric tons at an allowed rate of 10,000 MT per weather working day gives 6 days of laytime. Charter parties using rate-based laytime tie the allowance to the actual cargo quantity, which changes voyage by voyage.
Reversible vs. non-reversible: Where a voyage involves both a loading port and a discharging port, the charter party specifies whether laytime is reversible across both ports (time saved at load can offset overrun at discharge) or calculated separately at each port. Non-reversible laytime is the default in many standard forms. The difference can shift a demurrage figure significantly.
The Notice of Readiness (NOR)
The laytime clock does not start automatically on arrival. It starts — subject to charter party terms — on valid tender of the Notice of Readiness.
A Notice of Readiness (NOR) is a formal declaration by the vessel’s master that the ship has arrived at the agreed destination and is ready in all respects to load or discharge. “In all respects” means the vessel is physically ready: holds cleaned and inspected (for dry bulk), tanks prepared (for tankers), cargo gear operational, and all documentation in order.
The NOR triggers the laytime allowance. But when it is validly tendered, and when laytime actually commences from that tender, depends on the charter party terms — which brings us to some of the most disputed language in shipping contracts.
Key Charter Party Clauses That Govern Laytime Commencement
WIBON (Whether In Berth Or Not): Laytime commences on valid NOR tender regardless of whether the vessel has reached its berth. A vessel waiting at anchorage for a berth to become available can tender NOR under a WIBON clause, and laytime begins running while the vessel is still at anchor.
WIPON (Whether In Port Or Not): Similar to WIBON but broader — laytime commences on NOR tender whether or not the vessel is within the port limits. Used more commonly in tanker charters where the vessel may anchor outside the port area awaiting a berth or a free pratique.
WIBOLCON (Whether In Berth Or Lying On Congestion): A narrower variation that allows NOR tender if the vessel is lying at anchor due specifically to port congestion rather than any other reason. The distinction between congestion and other causes of delay is itself a source of dispute.
NAABSA (Not Always Afloat But Safely Aground): Relevant for ports where tidal conditions mean a vessel may ground at low tide. The clause allows the vessel to proceed into port and tender NOR without guaranteeing it remains afloat throughout.
Notice time: Many charter parties include a provision that laytime does not commence until a set number of hours after NOR tender, regardless of when the vessel is ready. “Laytime to commence 6 hours after NOR tendered” or “laytime to commence on first working day/shift after NOR acceptance” are typical formulations. This notice time is a commercial buffer for the charterer to prepare for cargo operations.
Excluded Periods
The laytime allowance is not a straight run of calendar time. Charter parties specify periods that are excluded from laytime counting:
Weather: Time lost to weather that prevents cargo operations is typically excluded from laytime under “weather working” clauses. Whether specific conditions qualify as weather that prevents operations is frequently disputed. The threshold (wind speed, swell height, visibility) is often not defined in the charter party and is determined by what actually happened on board and at the terminal.
Weekends and holidays: Many charter parties specify laytime counts on “working days” or “working time,” excluding Sundays and public holidays. The precise definition of a working day at a specific port — and whether local holidays apply — is a common source of calculation differences between owner and charterer.
Breakdown: Time lost to breakdown of vessel’s equipment or terminal equipment is typically excluded, though the charter party specifies which party bears responsibility.
Shifting: Time spent moving the vessel from one berth to another, or from anchorage to berth, may or may not count against laytime depending on the reason for shifting and the charter party terms.
Getting excluded periods right is where manual laytime calculations most commonly produce errors. A single miscategorised six-hour weather event on a vessel with a $20,000/day demurrage rate changes the claim by $5,000.
The Statement of Facts
The Statement of Facts (SoF) is the chronological record of a vessel’s port call. It documents, with timestamps, every relevant event from arrival through departure: NOR tender, pilot boarding, arrival at berth, commencement and completion of cargo operations, any stoppages (with reason), hatch-by-hatch progress where relevant, and departure.
The SoF is produced by the port agent and countersigned by the vessel’s master and typically a terminal representative. It is the primary source document for every laytime calculation and every demurrage claim.
Its importance cannot be overstated. If the SoF is inaccurate, incomplete, or inconsistent with other records, the laytime calculation built on it is vulnerable. Most demurrage disputes are not arguments about charter party interpretation. They are arguments about what the SoF says, what it means, and whether it accurately reflects what happened on board.
Common SoF problems that lead to disputes:
Vague event descriptions: “Operations slow due to rain” tells the laytime calculator nothing concrete about whether weather time should be excluded. “Rain commencing 0830, loading suspended 0845, loading resumed 1110” is calculable.
Missing events: Gaps in the sequence — no record of when the vessel moved from anchorage to berth, or when a specific hatch was opened — force the claims team to reconstruct from indirect sources.
Timezone errors: SoF timestamps recorded in local time without explicit notation, where the charter party calculation uses UTC, produce systematic errors across every time entry.
Late delivery: In many port calls, the SoF does not reach the charterer’s claims team until several weeks after the vessel has sailed. Context is lost. The ability to challenge or clarify specific entries diminishes with time.
A Laytime Calculation Example
The following is a simplified but realistic example of how a laytime calculation is constructed for a dry bulk voyage.
Fixture Details
- Vessel: MV Northgate, Panamax bulk carrier
- Cargo: 72,000 MT iron ore
- Load port: Port Hedland, Australia
- Discharging port: Qingdao, China
- Charter party: Non-reversible laytime
- Allowed laytime (loading): 72,000 MT ÷ 18,000 MT/WWDAY = 4.00 weather working days
- Allowed laytime (discharge): 72,000 MT ÷ 20,000 MT/WWDAY = 3.60 weather working days
- Demurrage rate: $22,000 per day (pro-rated)
- Notice time: Laytime commences 6 hours after NOR tender (SHEX — Sundays and holidays excluded)
Loading Port: Port Hedland
NOR tendered: Monday 14 April, 0800
Laytime commences: Monday 14 April, 1400 (6-hour notice time)
Vessel berthed: Monday 14 April, 1600
Loading commenced: Monday 14 April, 1800
Loading completed: Friday 18 April, 0600
Total laytime used (loading): 80.0 hrs = 3.33 weather working days
Laytime allowed: 4.00 weather working days
Time saved at load: 0.67 days (not applicable — non-reversible)
| Period | Hours | Counting? | Reason |
|---|---|---|---|
| Mon 1400 – Mon 1800 | 4.0 hrs | Yes | Waiting time, laytime running |
| Mon 1800 – Tue 1800 | 24.0 hrs | Yes | Loading in progress |
| Tue 1800 – Wed 0200 | 8.0 hrs | No (weather) | Rain — loading suspended 1800, resumed 0200 |
| Wed 0200 – Thu 0200 | 24.0 hrs | Yes | Loading in progress |
| Thu 0200 – Thu 1800 | 16.0 hrs | Yes | Loading in progress |
| Thu 1800 – Fri 0600 | 12.0 hrs | Yes | Loading completed 0600 |
| Total laytime used | 80.0 hrs | 8.0 hrs excluded (weather) · 8 hrs not counted | |
Discharging Port: Qingdao
NOR tendered: Thursday 1 May, 0600 (vessel at anchorage, WIBON clause)
Laytime commences: Thursday 1 May, 1200 (6-hour notice time, SHEX)
Vessel berthed: Saturday 3 May, 1400 (congestion delay — 43 hours at anchorage)
Loading commenced: Saturday 3 May, 1800
Discharge completed: Tuesday 6 May, 1400
Total laytime used (discharge): 98.0 hrs = 4.08 weather working days
Laytime allowed: 3.60 weather working days
Time on demurrage: 0.48 days × $22,000 = $10,560
Total claim: $10,560 demurrage at discharge.
| Period | Hours | Counting? | Reason |
|---|---|---|---|
| Thu 1200 – Fri 1200 | 24.0 hrs | Yes | Laytime running — WIBON, vessel at anchor |
| Fri 1200 – Sat 1200 | 24.0 hrs | No (SHEX) | Saturday excluded under charter party |
| Sat 1200 – Sat 1400 | 2.0 hrs | Yes | Laytime resumes at start of working period |
| Sat 1400 – Sat 1800 | 4.0 hrs | Yes | Vessel berthed, awaiting commencement |
| Sat 1800 – Sun 1800 | 24.0 hrs | No (SHEX) | Sunday excluded under charter party |
| Sun 1800 – Mon 1800 | 24.0 hrs | Yes | Discharging in progress |
| Mon 1800 – Tue 1400 | 20.0 hrs | Yes | Discharging completed 1400 |
| Total laytime used | 98.0 hrs | 48.0 hrs excluded (SHEX) · 48 hrs not counted | |
Note what this example illustrates: the WIBON clause meant laytime ran during the anchorage period, even before the vessel reached the berth. Without WIBON, the congestion waiting time would not have counted and there would be no demurrage at all. Charter party language changes the outcome of the arithmetic.
The Demurrage Claim Process
Once a voyage is complete, the sequence for a demurrage claim runs broadly as follows:
1. Claim submission. The shipowner (or their claims department) assembles the laytime statement, Statement of Facts, charter party, and any supporting documents — port logs, agent correspondence, master’s protest — and submits the claim to the charterer. Most charter parties specify a time bar: claims must be submitted within a defined period after completion of discharge, commonly 90 days. Claims submitted after the time bar may be legally unenforceable, regardless of their merits.
2. Charterer review.The charterer’s claims team reviews the laytime calculation against their own records. In practice, this means checking the SoF for accuracy, verifying that excluded periods have been correctly applied, confirming NOR validity, and comparing the owner’s calculation with an independent calculation from the charterer’s side.
3. Dispute and counter-claim. Where the charterer disagrees with the owner’s calculation, they issue a formal response identifying the disputed items. Common dispute grounds: NOR tendered before vessel was ready, excluded periods miscategorised, incorrect commencement time, wrong cargo quantity used in rate-based laytime. The response typically proposes a revised figure.
4. Negotiation. The majority of demurrage claims settle by negotiation rather than arbitration. The practical reality is that both parties have an incentive to settle: the owner wants cash, the charterer wants to close the liability. Most claims settle at a discount to the stated amount.
5. Arbitration. Where parties cannot agree, the dispute goes to arbitration under the terms of the charter party. LMAA (London Maritime Arbitrators Association) arbitration is the most common forum for English-law charterparties. Arbitration is expensive and slow. A claim worth less than $100,000 will often not justify the cost, which is why commercial settlement is the norm.
Disputes
Based on the structure of most demurrage claims, the most frequently contested items are:
NOR validity. Was the vessel ready in all respects when NOR was tendered? If the vessel’s holds were not clean, or if free pratique had not been granted, the NOR may not be valid, and laytime would only commence from when the deficiency was corrected.
Commencement time. Is the charter party commencement provision WIBON, WIPON, or berth-to-berth? The difference can mean hours or days of laytime counting before the vessel even arrives at the terminal.
Weather and breakdown exclusions. Were all weather stoppages correctly identified and excluded? Were any breakdown periods (particularly terminal equipment failures, which are typically excluded) incorrectly charged to the charterer?
Shifting time. Was time spent shifting counted against laytime? Was the shift for the vessel’s purposes or the terminal’s?
Cargo quantity. For rate-based laytime, was the correct bill of lading figure used? Differences between nominated, loaded, and documented cargo quantities affect the laytime allowance.
Why Demurrage Claims Are So Often Wrong
The gap between the demurrage amount initially claimed and the amount ultimately settled is a reliable indicator of how much systemic error exists in the process.
Owners have an incentive to claim the maximum supportable amount. Charterers have an incentive to reduce it. The settlement ends up somewhere between the two, shaped by the quality of each party’s documentation.
The underlying cause is structural. Port call data — the raw material of every laytime calculation — is still captured manually at most terminals. The Statement of Facts is produced by a port agent, typed or handwritten, and delivered to the charterer’s claims team days or weeks after the vessel has sailed. By then, the operator who managed the port call has moved on to other fixtures, the agent has no particular incentive to produce a detailed record, and the terminal’s logs are not always easily accessible.
When the claims team receives an SoF with a gap in the timeline, or a vague entry like “operations slow — terminal congestion,” the burden of proof falls on whoever is making the claim. If the SoF is ambiguous, the owner’s laytime calculation is weaker. If the charterer’s own records don’t capture what actually happened, their counter-claim is equally hard to support.
The result is a process that is inherently adversarial and inherently inefficient. Claims that should be resolved in days take months. Legitimate recovery is left on the table. Disputes that should be clear-cut become protracted negotiations because the underlying data is poor.
Reducing Demurrage Exposure: Operational and Commercial Levers
Demurrage reduction is not a claims management exercise. By the time the invoice arrives, the time has already been lost. The leverage is upstream.
Pre-arrival coordination. Confirming cargo readiness, berth availability, and documentation completeness before the vessel arrives at the anchorage is the highest-value lever. A vessel that arrives and can immediately tender a valid NOR, berth promptly, and commence operations without waiting for documents or cargo is a vessel that generates no demurrage.
Real-time event capture. The quality of the final laytime calculation is a direct function of how accurately port events were recorded as they happened. Operators who log NOR time, berthing time, stoppage reasons, and cargo figures in real time — rather than reconstructing from memory or from a late SoF — produce calculations that are harder to dispute and easier to defend.
Proactive NOR monitoring. On WIBON and WIPON charters, laytime may be running while the vessel is still at anchor. Charterers who do not monitor the NOR tender date and time against their port congestion picture lose laytime they could otherwise have been managing.
Claim validation before payment. Demurrage claims can contain errors that overstate the amount owed. A systematic review of every claim against the charter party and SoF — including excluded periods, NOR validity, and commencement time — will consistently reduce the settlement figure.
Benchmarking port performance. Over time, a charterer with structured records of port call performance can identify terminals and counterparties that consistently generate demurrage exposure, and factor that into fixture decisions, port rotation, and contract negotiations.
The Commercial Case for Structured Port Call Data
Most of what is described in this guide — from laytime calculation to dispute resolution — depends entirely on the quality of port call data. The problem is not that demurrage is complicated. The problem is that the information required to calculate it accurately is fragmented, delayed, and inconsistently captured.
Statements of Facts arrive late. Email chains are searched for timestamps that should have been in a structured record. Operators recall events from memory that should have been logged at the time. Claims teams rebuild calculations from incomplete documents rather than working from a clean data set.
The commercial consequence is measurable. Demurrage that should have been recovered is conceded because the documentation cannot support the claim. Demurrage that was not actually owed is paid because the charterer cannot demonstrate what the SoF got wrong. The time cost of processing each claim — assembling documents, calculating, reviewing, negotiating — runs to hours per claim for straightforward cases and days for disputed ones.
Frequently Asked Questions
Demurrage is compensation paid by the charterer to the shipowner when a vessel is kept beyond the agreed laytime, meaning the time allocated in the charter party for loading or discharging cargo. Once that allowance is used up, the clock starts on demurrage. The rate is fixed in the charter party, typically expressed as a daily figure, and it accrues continuously until cargo operations are complete and the vessel is free to sail.
It is not a penalty in the legal sense. It is a pre-agreed mechanism that compensates the owner for the productive time their vessel has lost.
Laytime is the period the charterer is allowed, under the charter party, to complete loading or discharging. Think of it as an included time budget. If operations finish within that window, no demurrage is owed. If they run over, demurrage begins from the moment the allowance is exhausted.
The two concepts are inseparable. You cannot calculate demurrage without first knowing how much laytime was allowed, when it commenced, which periods are excluded under the contract, and how much was actually consumed.
Demurrage starts the moment the charterer’s laytime allowance is fully used. But knowing precisely when that moment occurs requires working through several prior steps: when the Notice of Readiness (NOR) was tendered and accepted, which contract provisions govern the commencement of laytime (WIBON, WIPON, WIBOLCON and similar), which periods are excluded (weather, holidays, time not actually used), and whether any laytime was saved during one port that offsets another.
This sequence is where most disputes begin. The calculation is rarely straightforward, and the outcome depends heavily on how port events were recorded in the Statement of Facts.
The basic formula is: demurrage owed = (time on demurrage in days) × (demurrage rate per day).
In practice, getting to the time on demurrage figure requires a full laytime calculation: total laytime allowed under the charter party, minus excluded periods, against total time consumed from NOR acceptance to completion of operations. The difference, if the time consumed exceeds what was allowed, is the demurrage period.
Charter party terms vary significantly. Some contracts use reversible laytime across multiple ports, allowing time saved at one berth to offset overrun at another. Others are non-reversible, calculated port by port. These distinctions can shift a demurrage figure by hundreds of thousands of dollars on a single voyage.
Demurrage rates vary by vessel type, size, trade, and market conditions. As a general reference:
Handysize bulk carriers typically trade in the range of $5,000-$10,000 per day. Panamax and Kamsarmax vessels range from $8,000-$15,000. Capesize rates in active markets have moved above $30,000 per day during periods of congestion. VLCC tanker demurrage can run $50,000-$80,000 per day depending on the fixture.
These rates are fixed at the time of charter party negotiation, so the commercial exposure on a given voyage depends on both the rate agreed and how long the vessel ultimately sits waiting or operating.
A Statement of Facts (SoF) is the chronological record of a vessel’s port call: arrival, NOR tendering, pilot boarding, berthing, commencement and completion of cargo operations, any delays and their causes, and departure. It is produced by the port agent and countersigned by the vessel’s master and the terminal.
The SoF is the primary source document for any laytime calculation. If the SoF is incomplete, timestamped incorrectly, or inconsistent with other records, the laytime calculation built on it is vulnerable to dispute. Most demurrage disagreements trace back to ambiguities in the Statement of Facts, not to interpretation of the charter party itself.
Responsibility for demurrage sits with whoever caused the delay, but the charter party determines who is financially liable to the owner. In a voyage charter, the charterer is the primary counterparty for demurrage. The charterer may in turn have recourse against the terminal, shipper, or receiver depending on the underlying sale contract or port agreements, but those are separate commercial relationships.
Common causes of demurrage that fall on the charterer: congestion at load or discharge ports, delays in cargo readiness, slow cargo operations by the terminal, documentation delays. Common causes that fall on the owner or are excluded: vessel breakdown, crew issues, weather (where the charter party excludes weather time), port authority delays outside the charterer’s control.
A demurrage claim is a formal demand from the shipowner to the charterer for payment of demurrage accrued during a voyage. It should be accompanied by the laytime statement (the calculation), the Statement of Facts, the relevant charter party, and any supporting documentation for the time claimed.
The claims process typically follows this sequence: the owner submits the claim, the charterer reviews the laytime calculation against their own records, disputes are raised on specific items (invalid NOR, excluded periods, errors in timestamps), and the parties negotiate a settlement. Many claims are resolved at a negotiated discount because neither party wants the cost of arbitration.
Time bars are relevant here. Most charter parties contain a clause requiring demurrage claims to be submitted within a defined period after completion of discharge, typically 90 days. Claims submitted after the time bar expires may be unenforceable.
Most disputes arise from one of three sources: ambiguity in the charter party terms, poor documentation of port events, or disagreement about which delays are the charterer’s responsibility.
The documentation problem is the most prevalent and the most avoidable. When port agents produce Statements of Facts with inconsistent timestamps, vague event descriptions, or gaps in the sequence, the laytime calculation built on that data is contestable. Each contested line item becomes a negotiation. The cumulative effect on processing time and recovery rates is significant.
The fundamental issue is that port events are still, in most operations, captured manually and transmitted as PDFs. By the time the claims team receives the SoF, weeks may have passed, context is lost, and the ability to verify or challenge specific entries is limited.