Shipwrecking is an event that causes a shipwreck, such as a ship striking something that causes the ship to sink; the stranding of a ship on rocks, land or shoal; poor maintenance, resulting in a lack of seaworthiness; or the destruction of a ship either intentionally or by violent weather.
Causes
Factors for the loss of a ship may include:
poor design or failure of the ship's equipment or hull - pressure hull
instability, due to poor design, improperly stowed cargo, cargo that shifts its position or the free surface effect navigation errors and other human errors, leading to collisions (with another ship, rocks, an iceberg (), etc.) or running aground (Costa Concordia) bad weather and powerful or large waves or gale winds: This often leads to capsizing, also referred to as foundering warfare, piracy, mutiny, or sabotage including: guns, torpedoes, depth charges, mines, bombs and missiles fire biofouling, such as accumulation of polychaete and other tube worms on wood hulls overloading - either cargo or icing, and displacement exceeding the plimsoll line intentional sinking (scuttling) to form an artificial reef for wreck diving use as a target ship for training or testing weapons as a blockship to create an obstacle to close a harbour, river, etc. against enemy ships to prevent a ship from falling into an enemy's hands (e.g. Admiral Graf Spee) to destroy a derelict ship that poses a menace to navigation as part of an insurance scam
Design and equipment failure
The hallmark of a shipwreck due to poor design is the capsize of Swedish warship Wasa in Stockholm harbour 1628. She was too narrow, had too little ballast and her lower cannon deck had too low free-board for good seaworthiness. Poor design allowed the ferry MS Herald of Free Enterprise to put to sea with open roll-on/roll-off bow doors, with tragic consequences. Failure or leaking of the hull is a serious problem that can lead to the loss of buoyancy or the free surface effect and the subsequent sinking of the vessel. Even the hulls of large modern ships have cracked in heavy storms. Leaks between the hull planks of wooden vessels are a particular problem.
Equipment failure caused the shipwreck of cruiseferry Estonia in 1994. The stress of stormy seas on hull and bow especially caused the bow visor to break off, in turn tearing the watertight bow door open and letting seawater flow onto the car deck. She capsized with tragic consequences. Failure of pumps can lead to the loss of a potentially salvageable ship with only a minor leak or fire.
Failure of the means of propulsion, such as engines, sails or rigging, can lead to the loss of a ship. When the ship's movement is determined only by currents or the wind and particularly by storms, a common result is that the ship is unable to avoid natural hazards like rocks, shallow water or tidal races. Loss of propulsion or steering can inhibit a ship's ability to safely position itself in a storm, even far from land. Waves attacking a ship's side can overwhelm and sink it.
Instability and foundering
Instability is caused by the centre of mass of the ship rising above the metacenter resulting in the ship tipping on its side or capsizing. To remain buoyant, the hull of a vessel must prevent water entering the large air spaces of the vessel (known as downflooding). Clearly for the ship to float, the normally submerged parts of the hull will be watertight, but the upper parts of the hull must have openings to allow ventilation to compartments, including the engine room, for crew access, and to load and unload cargo. In a capsize, water can enter these openings if not watertight. If a ship sinks after capsizing, or as a consequence of a leak in the hull or other water ingress, it may be described as having foundered or foundering. Large ships are designed with compartments to help preserve the necessary buoyancy.