Ship cradle

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Empty ship cradle on steel rails Ship cradle.jpg
Empty ship cradle on steel rails

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.

Ship Large buoyant watercraft

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.

Boat vessel for transport by water

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.

Dry dock

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.

Overview

The Shetland ferry, MV Bigga, in its cradle Ship cradle2.jpg
The Shetland ferry, MV Bigga, in its cradle

"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.

Track (rail transport) rail infrastructure

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.

Tire ring-shaped covering that fits around a wheels rim

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.

Movement

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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Sail plan diagram of the masts, spars, rigging, and sails of a sailing vessel

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Mooring (watercraft) Any permanent structure to which a vessel may be secured

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.

Metacentric height measurement of the initial static stability of a floating body

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 construction and engineering of boats

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Dock (maritime) human-made structure involved in the handling of boats or ships

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Fishing trawler commercial fishing vessel designed to operate fishing trawls

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Slipway ramp on the shore by which ships or boats can be moved to and from the water

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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.

Strake

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Gantry crane

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Manoeuvring thruster transversal propulsion device built in to some ships and boats

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.

Shiplift

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.

Patent slip

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.

Fishing vessel boat or ship used to catch fish on a body of water

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.

Underfall Yard

The Underfall Yard is a historic boatyard on Spike Island serving Bristol Harbour, the harbour in the city of Bristol, England.

Caisson (lock gate) form of lock gate consisting of a large floating iron or steel box

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.