Ships - photo wallpapers; Photowallpapers.org A ship is a large, sea-going watercraft. Except sometimes, in ancient use, it is decked. A ship usually has sufficient size to carry its own boats, such as lifeboats, dinghies, or runabouts. A rule of thumb saying (though it doesnt always apply) goes: "a boat can fit on a ship, but a ship can't fit on a boat." Often local law and regulation will define the exact size (or the number of masts) which a boat requires to become a ship. (Note that one refers to submarines as "boats"). Compare vessel. One can measure ships in terms of overall length, length of the waterline, beam (breadth), depth (distance between the crown of the weather deck and the top of the keelson) and tonnage. A number of different tonnage definitions exist,: most measure volume rather than weight and are used when describing merchant ships. Gross tonnage is a measure of the total internal volume of the ship. Net Register Tonnage is expresses a merchant vessels earning capacity and gives the internal capacity of that part of the ship available for cargo or passengers. Thames tonnage was used for smaller vessels and worked to a formula: (length - beam) x beam x ˝beam / 94. The term displacement tonnage is normally applied when indicating the size of warships and equals the actual weight of a ship complete with crew, fuel, stores and water. "Light ship" tonnage measures the actual weight of the ship with no fuel, no persons, no cargo, no water on board is not usually quoted. The deadweight tonnage is the weight of cargo, stores, passengers etc. which when added to the weight of the ships structure and equipment, will bring the vessel down to her designed waterline. The word "displacement" arises from the basic physical law, discovered by Archimedes, that the weight of a floating object equates exactly to that of the water which would otherwise occupy the "hole in the water" displaced by the ship. In Britain, until the Merchant Shipping Act of 1876, ship-owners could load their vessels until their decks were almost awash, resulting in a dangerously unstable condition. Additionally, anyone who signed onto such a ship for a voyage and, upon realizing the danger, chose to leave the ship, could end up in jail. Samuel Plimsoll, a member of Parliament, realized the problem and engaged some engineers to derive a fairly simple formula to determine the position of a line on the side of any specific ship's hull which, when it reached the surface of the water during loading of cargo, meant the ship had reached its maximum safe loading level. To this day, that mark, called the "Plimsoll Mark", exists on ships sides, and consists of a circle with a horizontal line through the center. Because different types of water, (summer, fresh, tropical fresh, winter north Atlantic) have different densities, subsequent regulations required painting a group of lines forward of the Plimsoll mark to indicate the safe depth (or freeboard above the surface) to which a specific ship could load in water of various densities. Hence the "ladder" of lines seen forward of the Plimsoll mark to this day. During the age of sail, ship signified a ship-rigged vessel, that is, one with three or more masts, usually three, all square-rigged. Such a vessel would normally have one fore and aft sail on her aftermost mast which was usually the mizzen. Almost invariably she would also have a bowsprit but this was not part of the definition. The same economic pressures which increased sizes to the point of carrying four or five masts, also introduced the fore and aft rig to larger vessels, so few ship-rigged vessels were built with more than three masts. The five-masted Preussen was the outstanding example but the big German ships and barques were built partly for prestige reasons. Nautical means related to sailors, particularly customs and practices at sea. Naval is the adjective pertaining to ships though in common usage, it has come to be more particularly associated with the noun navy.
