Deep diveChemical Trading

How demurrage builds up on chemical tanker voyages, and how to claim it faster

Demurrage on chemical tankers is rarely one large loss. It is a run of small, arguable delays across ports, parcels and terminals, each governed by wording that changes between fixtures. This page explains how laytime accrues on parcel voyages, which events decide a claim, and where AI can take over the reading, reconciling and deadline tracking.

Reviewed 10 October 2026 8 min read

On this page

Why demurrage keeps leaking margin from chemical trades
The laytime vocabulary that decides who pays for waiting
Where a chemical parcel voyage loses time, and what settles the argument
Multi-port, multi-parcel voyages: allocating time before arguing delays
From statement of facts to a settled claim
Estimating demurrage exposure before the vessel is fixed
A two-port glycol discharge with disputed shore delays
Where automated claims handling goes wrong
Questions and answers
Sources

Why demurrage keeps leaking margin from chemical trades

A chemical trader's freight is agreed when the vessel is fixed, but the cost of waiting is only known after the last hose comes off. Parcel tankers often carry several grades for several charterers, call at more than one terminal at each end, and depend on shore tanks, pipelines and surveyors being ready on time. Each dependency can turn into hours on demurrage at the rate written into the fixture.

The money rarely goes in one incident. It drains through berth congestion, waiting for tank inspection, slow pumping nobody challenged, and claims never passed to the buyer or supplier who caused the delay.

Most parcel chemical business is still fixed on general tanker forms. BIMCO has noted the trade's move to heavily amended ASBATANKVOY forms, one reason it rewrote its chemical tanker charter as BIMCHEMVOY 2008². Riders, recap terms and incorporated definitions therefore decide most claims, and must be read fixture by fixture.

The laytime vocabulary that decides who pays for waiting

Where a charter party expressly incorporates the BIMCO Laytime Definitions for Charter Parties 2013, these terms carry the defined meanings; otherwise the form's own wording and the governing law decide¹.

Notice of readiness (NOR): The master's notice that the vessel has arrived and is ready in all respects to load or discharge. An invalid notice can delay the start of laytime, so its time, method of tender and any rejection must be recorded exactly.
Laytime: The time allowed for loading and discharging without payment beyond the freight. Tanker fixtures often give a total of running hours for both ends, which makes laytime reversible: time saved loading can absorb delay discharging.
Laytime exceptions: Periods that do not count, such as shifting from anchorage to berth or delay caused by the vessel. Whether they apply once on demurrage depends on the wording.
Demurrage: The agreed amount owed to the owner for delay after laytime expires. Under the BIMCO definitions it is generally not reduced by laytime exceptions unless the charter party says so, and once running it continues unless a clause clearly interrupts it.
Half-rate demurrage: Under clause 8 of ASBATANKVOY, demurrage caused by fire, explosion, storm, strikes or breakdown at the charterer's, supplier's or receiver's facilities is charged at half the rate, and courts have tested what counts as a breakdown³.
Statement of facts (SOF): The port agent's timeline of the call, from arrival and NOR to hoses off. Signed remarks on it frequently decide a dispute.
Time bar: A clause that extinguishes a claim unless it is presented, with the listed documents, within a stated period after discharge. Such clauses are usually applied strictly, so one missing pumping log can defeat a sound claim.

Where a chemical parcel voyage loses time, and what settles the argument

The same delay can be the owner's risk on one fixture and the charterer's on the next. These events appear most often in chemical tanker claims.

Event	Evidence that settles it	Usually pressed by	What to check in the fixture
Berth congestion	Terminal line-up, berthing prospects, AIS position at anchorage	Owners, to start laytime from NOR rather than berthing	Whether NOR may be tendered whether in berth or not
Shore tank full or not ready	Terminal tank records, receiver emails, SOF remarks	Owners; charterers may seek the half rate for a shore breakdown	Half-rate causes and who bears receiver-side delay
Slow pumping	Pumping log, manifold pressure records, written shore restrictions	Charterers, to deduct time beyond the pumping warranty	Warranty wording and whether restrictions were noted at the time
Tank inspection failure	Surveyor reports, inspection certificates, cleaning records	Charterers, to exclude time while the vessel was not ready	Whether NOR was valid before tanks passed
Shifting between berths	SOF times for anchor aweigh, all fast and hoses on at each berth	Both sides, over whether shifting time counts	Shifting clauses and treatment of multi-terminal ports

Simplified for illustration; outcomes turn on the exact clauses, governing law and evidence. Not legal advice.

Multi-port, multi-parcel voyages: allocating time before arguing delays

One parcel tanker call can serve several charterers, and one cargo may load at two terminals and discharge at three. Before any delay is argued, port time has to be split between parcels, usually pro rata to quantity, with separate rules for time spent on one parcel alone. A wrong allocation produces a claim that contradicts itself.

Chemical cargoes add their own waiting. Tankers built under the IMO's IBC Code carry each product under specific carriage requirements, and MARPOL Annex II, which sorts noxious liquid substances into pollution categories, governs tank washing and residues⁵. Heating records and commingling consents also belong in the claim file.

From statement of facts to a settled claim

AI earns its place in the middle of the claims process: reading, lining up timestamps and keeping deadlines. The negotiating position stays with the analyst.

Voyage documents in
Charter party and recap, NOR, statements of facts, pumping logs and surveyor reports, in any format.
Event extraction
Timestamped events with time zone, source page and confidence; signed remarks kept as text.
Cross-check with AIS
Arrival and berthing times compared with AIS and terminal records; conflicts go to a person.
Laytime calculation
Confirmed clauses applied per parcel and port, each deduction linked to its clause.
Claim or counter-claim
The analyst finalises and sends the claim, or checks a counterparty's line by line.
Pass-through to contracts
The timeline is re-run under the sale or purchase contract to recover or defend the delay.
Time-bar watch
Deadlines on every linked contract tracked from the end of discharge.

Conceptual flow of an AI-assisted demurrage claims process; tools and order vary by firm.

Estimating demurrage exposure before the vessel is fixed

Most demurrage is decided by the choice of terminal, season and vessel before fixing. A pre-fixture estimate turns past calls into a cost traders can price.

Build a port-time history
Assemble past calls by terminal from your own statements of facts and AIS data, with the reasons recorded for waiting. Your history reflects your grades better than port averages.
Output
Port-time history by terminal
Segment by what drives waiting
Split by season, parcel size, number of grades and loading or discharging end; shared chemical jetties behave differently around maintenance periods.
Apply the draft fixture terms
Run expected port time through the proposed laytime, NOR wording, exceptions and rate. Offers with equal freight can carry very different waiting costs.
Output
Expected demurrage per offer
Re-estimate at nomination
Update when vessel, terminal slot and parcel mix are confirmed, and alert the operator if exposure leaves the range the trader accepted.
Owner
Operations

A two-port glycol discharge with disputed shore delays

Hypothetical example

Two receivers, one slow pump and a disputed anchoring time

Suppose a trader sells monoethylene glycol to two receivers at two ports, on an amended tanker form with reversible laytime and a pumping warranty. At the first port the receiver's tank is nearly full and the terminal restricts the rate, so the vessel pumps slowly for most of a day. At the second it waits at anchorage.

The owners claim for both ports. The master's remark about the shore restriction, made at the time, means the slow pumping probably stays in the owners' claim; but the receiver caused it, so the analyst re-runs it under the sale contract and passes it to the buyer.

At the second port, AIS shows the vessel anchoring hours before the agent's NOR time, so the analyst queries the agent. The sale contract's time bar, shorter than the charter party's, sets the first deadline.

Where automated claims handling goes wrong

Time zones misread

Early signalDocuments disagree by whole hours.

MitigationStore each timestamp with its zone and source; convert only when calculating.

Remarks dropped during extraction

Early signalThe extracted timeline looks cleaner than the signed document.

MitigationExtract remarks and letters of protest as events and show them beside the times they qualify.

Wrong terms applied

Early signalRecap amendments or riders are missing from the file.

MitigationTreat recap and riders as governing, record the version used and have a person confirm it.

Confidence scores trusted blindly

Early signalLow-confidence events flow straight into a claim.

MitigationRoute them to a reviewer, following the approval patterns used for AI agents: the system drafts, a person signs.

Questions and answers

Can AI calculate laytime from a scanned statement of facts?

It can extract the events and draft the calculation; the dependable part is the extraction and cross-checking, not the judgement. Scanned statements with stamps and handwriting can be read, with each event linked to its source line and a confidence score. The calculation applies clauses an analyst has confirmed, and conflicts or missing remarks come back to a person before any claim is sent.

How should demurrage be passed on to the buyer or supplier who caused it?

Re-run the voyage timeline under the sale or purchase contract's own laytime clause, which often differs from the charter party in allowance, notice rules and time bar. Recovery is not automatic: the delay must fall within that contract's terms, and the claim must arrive with the documents it requires before its own deadline.

Is AIS data reliable enough to challenge a notice of readiness time?

AIS is strong supporting evidence of where a vessel was and when it stopped, and SOLAS requires it on most cargo ships trading internationally⁴. It is not conclusive alone: signals drop, positions can be wrong, and anchoring is not the same as being ready. Use it to test the agent's timeline, and rely on signed documents for the argument.

Does ColdAI replace our laytime calculator or operations system?

Not necessarily. ColdAI's chemical trading work can run as a layer that reads documents, reconciles events and tracks deadlines, then hands results to the operations or claims system you already use. Where no structured claims tool exists, the same components can form one. Either way the analyst signs off; the system prepares the evidence.

Sources

Laytime Definitions for Charter Parties 2013 — BIMCO · checked 10 October 2026
BIMCHEMVOY 2008: standard voyage charter party for chemical tankers, explanatory notes — BIMCO · checked 10 October 2026
Half demurrage under the ASBATANKVOY form, clause 8 — Skuld · checked 10 October 2026
AIS transponders — International Maritime Organization · checked 10 October 2026
International Code for the Construction and Equipment of Ships carrying Dangerous Chemicals in Bulk (IBC Code) — International Maritime Organization · checked 10 October 2026

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