Definition
Lay days are the number of days allowed by a charter party for the loading and unloading of a vessel's cargo. The term appears in maritime and shipping law as a contractual unit of time: the shipowner agrees to make the vessel available, and the charterer or consignee is allotted a fixed number of days to complete cargo operations at the port. If the charterer fails to complete loading or unloading within the allotted lay days, the excess time is called demurrage, and the charterer typically owes the shipowner compensation at a predetermined daily rate. Conversely, if cargo operations are completed ahead of schedule, the shipowner may owe the charterer dispatch money under some agreements.
Lay days may be fixed (a specific number of calendar or working days), running (counting continuously from the moment the vessel is ready), or weather working (excluding days on which weather prevents cargo operations). The charter party itself defines which type applies, and disputes often turn on exactly when the lay day count begins — a point triggered by the vessel's arrival, the tendering of a notice of readiness, or both.
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Common Language
Modern common usage (Wiktionary): Simply the plural of "lay day," which in ordinary usage can refer to a day of rest or a day without scheduled activity.
Historical common usage (Webster's 1913): Not separately listed; "lay" in its adjectival sense denoted rest, inactivity, or a non-working period.
The common usage captures only the surface idea of a day not spent in active work. In the legal and commercial sense, lay days are a precisely bounded contractual entitlement — a countdown with real financial consequences on either end. The casual meaning of "a day off" obscures that lay days are neither passive nor consequence-free: they are a measured performance window, and their expiration triggers enforceable liability.
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Why It Matters in Research
Lay days sit at the intersection of contract law and maritime law, which means a researcher must track them across two bodies of doctrine that evolved somewhat independently.
The most important research trap is the Sundays question. Historical practice varied: some ports and some charter parties excluded Sundays and holidays from the lay day count (treating them as non-working days), while others ran the count continuously. Bouvier flags this directly, noting that in the absence of contrary custom, Sundays were computed in lay days at the port of discharge. A researcher reading older charter party disputes must determine which rule applied — the charter party text, port custom, or a default rule — before interpreting the outcome of any historical dispute.
Notice of readiness is a second research trap. Modern lay day law turns heavily on when the notice of readiness is validly tendered, which starts the clock. Historical sources predate the formalization of this doctrine and may discuss the commencement of lay days in ways that do not map cleanly onto contemporary port practice or modern standard-form charter parties (such as the GENCON or ASBATANKVOY forms).
Demurrage is the natural downstream term and appears in virtually every source that discusses lay days. Researchers following a chain of historical authorities will move between these two terms constantly; Bouvier's entry for lay days explicitly cross-references demurrage, and any thorough search on one term requires searching the other.
Jurisdictional variation matters less here than choice-of-law: because charter parties routinely select English law or New York law as governing, the bulk of developed lay day doctrine is English admiralty law and U.S. federal maritime law. State common law is rarely the controlling body of authority in disputes involving ocean-going vessels.
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Historical Dictionary Support
Black's, Bouvier's, and Burrill's agree on the core definition without meaningful divergence: lay days are the days allowed under a charter party for loading and unloading. All three cite 3 Kent's Commentaries 202–203, making that the foundational treatise reference across all three sources.
Bouvier's is the most substantive of the three. It adds the Sundays rule, cites several additional authorities including Espinasse and Stephens, and — significantly — connects the entry directly to demurrage. Black's and Burrill's treat the term as definitional rather than doctrinal, providing essentially the same one-sentence gloss.
What the historical dictionaries collectively miss is the developed law of notice of readiness, the distinction between running days, working days, and weather working days, and the role of standard-form charter parties in modernizing how lay days are calculated. A researcher relying solely on these sources will have the foundational concept but will need to supplement with admiralty treatises and charter party commentary for anything beyond a basic historical inquiry.
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Jurisdictional Note
In the United States, lay day disputes in ocean shipping are governed by federal maritime law and are within the admiralty jurisdiction of federal courts. English admiralty law is highly persuasive and often directly controlling when the charter party specifies English law as governing. Researchers should expect that the most developed and frequently cited body of lay day doctrine originates in English cases, not American ones.
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