Aground
Aground describes a ship whose hull is resting on or stuck against the seabed (or a shoal, reef or bank) and is no longer freely afloat. Running aground (grounding) happens when a vessel enters water too shallow for its draft — through navigational error, losing control (going adrift), or being driven ashore by weather.
Grounding is a serious maritime casualty: it can cause hull damage, flooding, pollution, and loss of the ship, and refloating may require lightening the ship (removing cargo/ballast), tugs, salvage and favourable tides. A vessel aground must display the correct signals/lights under the COLREGs. Grounding risk is precisely why under-keel clearance, accurate charts, passage planning and pilotage matter so much, and why adequate draft management and channel depth are critical. (A deliberate, controlled grounding — beaching — is used by some craft like landing craft, or as an emergency measure.) Aground is a fundamental term of navigation safety, describing a ship that has met the bottom — one of the outcomes that safe navigation exists to prevent. It denotes a grounded, immobilised vessel.
Grounding is one of the classic ways ships come to grief — hull damage, flooding, pollution, even total loss — and it is exactly what under-keel clearance, charts, passage planning and pilotage exist to prevent. Understanding "aground" underscores why draft and channel depth are watched so closely in safe navigation.
What causes a ship to run aground?
Entering water too shallow for its draft — through navigational error, loss of control, or being driven ashore by weather.
How is a grounded ship refloated?
Often by lightening it (removing cargo or ballast), tug assistance, salvage and using a rising tide.