Definition
A vessel is under way when it is not anchored, moored, made fast to the shore, or aground. The term is a term of art in admiralty and maritime law used to determine a vessel's navigational status for purposes of collision rules, statutory duties, and liability. Being under way does not require that a vessel be in actual motion through the water — a vessel may be under way while stationary, so long as it is free from any fixed connection to the ground or shore.
Common Language
Modern common usage (Wiktionary): In operation, in progress, or commenced; also, moving through the water as opposed to anchored, moored, aground, or beached; into motion or into its course.
Historical common usage (Webster's 1913): Having way; in motion; progressing; said of a vessel.
The common usage and the legal usage share a core idea but diverge at a critical point. Ordinary speakers understand "under way" to mean actively moving — a ship that is sitting still would not intuitively seem to be "under way." Maritime law reaches the opposite conclusion: a vessel may be under way while making no headway at all, provided it has no fixed ground tackle holding it in place. This distinction has real legal consequence, particularly in collision and towage cases where fault turns on which vessels were under way at the relevant moment.
Common Confusion
The principal confusion is between a vessel that is under way and a vessel that is making way. A vessel under way is simply free from anchorage, mooring, or grounding. A vessel making way is actually propelling itself through the water. The International Regulations for Preventing Collisions at Sea (COLREGS) treat these as distinct conditions, and the duties imposed — such as the requirement to show certain lights or sound signals — depend on which condition applies. Historical sources sometimes use "under way" loosely to mean "in motion," which can mislead a researcher examining older collision cases.
Why It Matters in Research
The legal definition of under way is outcome-determinative in admiralty collision cases. Whether a vessel was under way at the time of an incident governs which rules of the road applied, which lights were required, and which fault standards apply. Researchers examining nineteenth- and early twentieth-century admiralty decisions must be alert to two hazards.
First, the definition was actively contested in that period. Courts were working out the edges of the rule — whether a tug fast alongside another vessel while maneuvering it counted as under way, whether a vessel with anchor down but not gripping the bottom was under way. Bouvier's cites cases on both of these precise questions, and the answers are not self-evident. A researcher assuming the term had a fixed, settled meaning throughout the nineteenth century may misread the posture of older cases.
Second, the statutory and regulatory background shifted across the relevant period. The rules governing lights, signals, and right-of-way for vessels under way evolved through successive international conventions and domestic enactments. An opinion's holding on what "under way" means must be read against the specific regulatory regime in effect at the time, not projected forward or backward onto a different set of rules.
For corpus researchers, the term appears most frequently in collision and towage contexts, and connections run to entries on pilotage, towage liability, and the inland and international rules of the road. The question of anchor status — whether a vessel at anchor is or is not under way — is a recurring flashpoint that links this term to the law of anchorage and to the statutory definitions found in successive navigation acts.
Historical Dictionary Support
Bouvier's treatment of under way is narrow but instructive. Rather than offering a general definition, Bouvier's proceeds immediately to contested factual scenarios, which signals that by the time of that edition the core definition was not in serious dispute but its application at the margins was actively litigated.
Two specific holdings are cited. First, a steam tug fast alongside a vessel she was moving up to her anchor in preparation for towing was held to be under way — the tug's navigational engagement, not her physical separation from another vessel, was the operative fact. Second, a vessel with her anchor down but not actually held by or under control of it was also held to be under way — the anchor's physical presence was irrelevant; what mattered was whether it was actually performing its holding function.
Both propositions converge on the same principle: under way is a legal status defined by the absence of effective fixed connection, not by motion. Bouvier's does not explore the making-way distinction or engage with the international regulatory framework in depth, which reflects the reference conventions of its era. Researchers should treat Bouvier's here as a doctrinal snapshot, not a comprehensive treatment. The references to the American and English Encyclopedia of Law (2nd ed.) and the admiralty report citations point toward the primary materials where the fuller doctrinal development can be traced.
Jurisdictional Note
The definition of under way in American maritime law has generally tracked international convention definitions, particularly as codified in the COLREGS and their predecessor agreements. Inland waters rules historically differed from international rules in some navigational requirements, but the basic status definition of under way has been substantially consistent across both regimes.