The basic idea
Laytime is the contractually allowed time for loading or discharging. When the charterer uses more than the allowed time, demurrage may become payable at the agreed rate. Where the contract provides for it, completing within the allowed time may create despatch.
A simple example
A charter allows 72 running hours to load. Valid laytime starts at 12:00 on Monday. The operation finishes at 18:00 on Thursday. The raw elapsed time is 78 hours. If six hours are excluded under the charter party, the counted time is 72 hours and no demurrage is due. Change one exception or the validity of the Notice of Readiness, and the result changes.
The documents that matter
The charter party defines the rules. The Notice of Readiness may trigger the laytime mechanism. The Statement of Facts records the sequence of events. Timesheets, weather records, pumping logs, letters of protest and terminal records may support or challenge the calculation.
Common causes of dispute
Typical issues include premature or invalid NOR, berth versus port charter wording, weekends and holidays, weather interruptions, shifting time, breakdowns, congestion, cargo unavailability, documentation delays, reversible laytime, once-on-demurrage principles and claim time bars.
How software helps—and where it cannot decide
Software can structure events, apply configured rules, preserve source documents, flag inconsistencies and generate a transparent calculation. It should not pretend that every clause has one obvious interpretation. Human review remains necessary where facts or legal meaning are disputed.
Frequently asked questions
What is the difference between laytime and demurrage?
Laytime is the allowed cargo-handling time. Demurrage is the agreed compensation that may be payable when counted time exceeds that allowance.
Does bad weather always stop laytime?
No. The answer depends on the charter-party wording, the stage of the operation and the facts recorded.
Can AI calculate demurrage?
AI can extract events and assist with a draft, but the final result should be checked against the governing contract and evidence.