Flotsam, jetsam, lagan, and derelict

In maritime law, flotsam, jetsam, lagan, and derelict are specific kinds of shipwreck. The words have specific nautical meanings, with legal consequences in the law of admiralty and marine salvage. A shipwreck is defined as the remains of a ship that has been wrecked, a destroyed ship at sea, whether it be sunken or floating on the surface of the water.

A wreck is categorized as property belonging to no apparent owner, that either sinks to the seabed, or floats on the surface of the water, whether it be intentionally cast overboard, or as the result of an accident. The term encompasses the hull of the vessel and its fixtures, as well as any other form of object onboard, such as cargo and stores, and personal effects of the crew and passengers. This also encompasses the narrower definition of salvage, that is, property that has been recovered from a wreckage, or the recovery of the ship itself.

There are a number of factors that contribute to the formation of a shipwreck, that can be divided into physical and cultural processes. A site can be affected by physical processes, that is, naturally occurring processes, such as the corrosion caused by salinity and ocean currents, or the growth of native and foreign marine organisms. It can also be affected by cultural processes, that is, by human interactions, such as adding or removing materials from the site of the wreck. Any archaeological activity, such as excavation, may also be considered invasive and tampering.

In terms of maritime law, different meanings are attributed to the terms, based on what the jurisdiction is, as well as the context. For example, a distinction is made between goods that wash ashore, from those that are for some reason not salvageable and/or lost at sea.

Ownership of a wreck is a highly controversial issue, as there are no clear lines within which it is defined. It may be acquired through various means that range from succession to confiscation. There is also a distinction to be made between the ownership of the hull itself and the cargo it contains, as the hull may be abandoned intentionally, whereas the cargo may be out of necessity (in the case of an emergency or the need to shed weight from the vessel). In these parameters, abandonment of the ship by its passengers constitutes as a loss of possession, but to abandon the claim on the title itself, intention to relinquish it is required. This affects wrecks by limiting that which is considered “abandoned”. Generally, a ship is defined as “abandoned” if there is no hope of recovery, known legally as Sine spe recuperandi (which is the Latin phrase for "no hope of recovery"), and this fact must be clearly proven by the salvaging party. It must also occur on navigable waters.

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