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A ship cradle is a rig designed to hold a ship or boat upright on dry land to allow the vessel to be built or repaired. The vessel is held in place in the cradle by wooden chocks, cables, sand bags or restraining fixtures on the cradle. Ship cradles are made of timber or steel and are usually built adjacent the seashore, lake or river side or on the floor of a dry dock.
A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying passengers or goods, or in support of specialized missions, such as defense, research and fishing. Historically, a "ship" was a sailing vessel with at least three square-rigged masts and a full bowsprit. Ships are generally distinguished from boats, based on size, shape, load capacity, and tradition.
A boat is a watercraft of a large range of type and size. Ships are generally distinguished from boats based on their larger size, shape, and cargo or passenger capacity.
A dry dock is a narrow basin or vessel that can be flooded to allow a load to be floated in, then drained to allow that load to come to rest on a dry platform. Dry docks are used for the construction, maintenance, and repair of ships, boats, and other watercraft.
"Cradle" may refer to the whole rig or sometimes each section of it. The cradle may be fixed to the dock floor, relying on the tides or a dry dock to drain it, or be equipped with wheels, running on an inclined track to allow the ship to be moved out of the water to a dry parking area. Large or heavy ships require steel railway wheels running on fixed steel tracks; cradles designed for smaller boats may have rubber-tyred wheels, usually running on a concrete slipway, and can be moved anywhere in the boatyard.
The track on a railway or railroad, also known as the permanent way, is the structure consisting of the rails, fasteners, railroad ties and ballast, plus the underlying subgrade. It enables trains to move by providing a dependable surface for their wheels to roll upon. For clarity it is often referred to as railway track or railroad track. Tracks where electric trains or electric trams run are equipped with an electrification system such as an overhead electrical power line or an additional electrified rail.
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface traveled over. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, which also provide a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over by providing a bearing pressure that will not deform the surface excessively.
Most cradles with steel wheels can move only in one direction, following the cradle rail track and designed to lift the vessel out of the water either longitudinally (bow-stern) or transversely (across the beam). The empty cradle shown top right extracts the ship longitudinally but its wheels can then be rotated 90o allowing it to park the ship transversely and freeing up the slipway for another vessel. The ferry bottom right can also be transported in the longitudinal as well as the transverse direction but uses a separate transverse carriage to change direction.
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The hull is the watertight body of a ship or boat. Atop the hull may be a deckhouse or some other form of superstructure, like a mast. The line where the hull meets the water surface is called the waterline.
Ceremonial ship launching is the process of transferring a vessel to the water. It is a naval tradition in many cultures, dating back thousands of years. It has been observed as a public celebration and a solemn blessing.
Naval architecture, or naval engineering, along with automotive engineering and aerospace engineering, is an engineering discipline branch of vehicle engineering, incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process, shipbuilding, maintenance, and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation (classification) and calculations during all stages of the life of a marine vehicle. Preliminary design of the vessel, its detailed design, construction, trials, operation and maintenance, launching and dry-docking are the main activities involved. Ship design calculations are also required for ships being modified. Naval architecture also involves formulation of safety regulations and damage-control rules and the approval and certification of ship designs to meet statutory and non-statutory requirements.
A sail plan is a set of drawings, usually prepared by a naval architect which shows the various combinations of sail proposed for a sailing ship. Alternatively, as a term of art, it refers to the way such vessels are rigged as discussed below.
A mooring refers to any permanent structure to which a vessel may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An anchor mooring fixes a vessel's position relative to a point on the bottom of a waterway without connecting the vessel to shore. As a verb, mooring refers to the act of attaching a vessel to a mooring.
The metacentric height (GM) is a measurement of the initial static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre. A larger metacentric height implies greater initial stability against overturning. The metacentric height also influences the natural period of rolling of a hull, with very large metacentric heights being associated with shorter periods of roll which are uncomfortable for passengers. Hence, a sufficiently, but not excessively, high metacentric height is considered ideal for passenger ships.
Boat building is the design and construction of boats and their systems. This includes at a minimum a hull, with propulsion, mechanical, navigation, safety and other systems as a craft requires.
A dock is the area of water between or next to one or a group of human-made structures that are involved in the handling of boats or ships or such structures themselves. The exact meaning varies among different variants of the English language.
A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets that are pulled along the bottom of the sea or in midwater at a specified depth. A trawler may also operate two or more trawl nets simultaneously.
A slipway, also known as boat ramp or launch or boat deployer, is a ramp on the shore by which ships or boats can be moved to and from the water. They are used for building and repairing ships and boats, and for launching and retrieving small boats on trailers towed by automobiles and flying boats on their undercarriage.
This is a partial glossary of nautical terms; some remain current, while many date from the 17th to 19th centuries. See also Wiktionary's nautical terms, Category:Nautical terms, and Nautical metaphors in English. See the Further reading section for additional words and references.
A strake is a course of the planking or plating of the hull of a vessel. In a wooden construction it is a strip of planking running longitudinally along the vessel's bottom and sides. In a metal ship it is a course of plating.
A gantry crane is a crane built atop a gantry, which is a structure used to straddle an object or workspace. They can range from enormous "full" gantry cranes, capable of lifting some of the heaviest loads in the world, to small shop cranes, used for tasks such as lifting automobile engines out of vehicles. They are also called portal cranes, the "portal" being the empty space straddled by the gantry.
Manoeuvring thruster is a transversal propulsion device built into, or mounted to, either the bow or stern, of a ship or boat to make it more maneuverable. Bow thrusters make docking easier, since they allow the captain to turn the vessel to port or starboard side, without using the main propulsion mechanism which requires some forward motion for turning; The effectiveness of a thruster is curtailed by any forward motion due to the Coandă effect. A stern thruster is of the same principle, fitted at the stern. Large ships might have multiple bow thrusters and stern thrusters.
A shiplift is a modern alternative for a slipway, a floating dry dock or a graving dry dock. A shiplift is used to dry dock and launch ships. It consists of a structural platform that is lifted and lowered exactly vertically, synchronously by a number of hoists. First, the platform is lowered underwater, then the ship is floated above the support, and finally the platform with support and ship is lifted and the ship is brought to the level of the quay.
The patent slip or marine railway is an inclined plane extending from shoreline into water, featuring a "cradle" onto which a ship is first floated, and a mechanism to haul the ship, attached to the cradle, out of the water onto a slip. The marine railway was invented by a Scot, Thomas Morton, in the early 19th century, as a cheaper alternative to dry docks for marine vessel repairs, in particular below waterline. Larger modern marine railways can handle vessels of thousands of tons.
A fishing vessel is a boat or ship used to catch fish in the sea, or on a lake or river. Many different kinds of vessels are used in commercial, artisanal and recreational fishing.
The Underfall Yard is a historic boatyard on Spike Island serving Bristol Harbour, the harbour in the city of Bristol, England.
A caisson is a form of lock gate. It consists of a large floating iron or steel box. This can be flooded to seat the caisson in the opening of the dock to close it, or pumped dry to float it and allow it to be towed clear of the dock.