Ship building and repairing

Shipbuilding is the construction of ships. It normally takes place in a specialized facility known as a shipyard. Shipbuilders, originally called shipwrights, follow a specialized occupation that can trace its roots to before recorded history. The construction of boats is a similar activity called boat building. The dismantling of ships is called ship breaking.
== History ==
Evidence from ancient Egypt shows that the early Egyptians already knew how assemble planks of wood into a watertight hull, using treenails to fasten them together, and pitch for caulking the seams. The ships of the Eighteenth Dynasty were typically about 25 meters (80 ft) in length, and had a single mast, sometimes consisting of two pole lashed together at the top making an "A" shape. They mounted a single square sail on a yard, with an additional spar along the bottom of the sail. These ships could also be oar propelled.
The ships of Phoenicia seems to have been of a similar design. The Greeks and probably others introduced the use of multiple banks of oars for additional speed, and the ships were of a light construction, for speed and so they could be carried ashore.
Viking longships developed from an alternate tradition of clinker-built hulls fastened with leather thongs. Sometime around the 12th century, northern European ships began to be built with a straight sternpost, enabling the mounting of a rudder, which was much more durable than a steering oar held over the side. Development in the Middle Ages favored "round ships", with a broad beam and heavily curved at both ends.
The introduction of cannons onto ships encouraged the development of tumblehome, the inward slant of the abovewater hull, for additional stability, as well as techniques for strengthening the internal frame.
These kinds of considerations, as well as the demand for ships capable of operating safely in the open ocean, led to the documentation of design and construction practice in what had previously been a secretive trade, and ultimately the field of naval architecture. Even so, construction techniques changed only very gradually; the ships of the Spanish Armada were internally very similarly to those of the Napoleonic Wars over two centuries later.
Iron was gradually adopted in ship construction, initially in small areas needing greater strength, then throughout, although initially copying wooden construction. Isambard Brunel's Great Britain of 1843 was the first radical new design; built entirely of iron, using stringers for strength, inner and outer hulls, and bulkheads to form multiple watertight compartments. Despite her success, many yards only went so far to use composite construction, with wooden timbers laid over an iron frame (the Cutty Sark is so constructed). Steel supplanted iron when it became readily available in the latter half of the 19th century.
Wood continued to be favored for the decks, and is still the rule for modern cruise ships.
===Shipwrights in England===
During the 16th century Shipwrights in England were so few in number as to be granted direct employment by the Crown. The first list of ‘Master Shipwrights’ appointed ‘by Patent’ was issued by Henry VIIIth and included ‘John Smyth, Robert Holborn, Richard Bull and James Baker’ (father of Mathew Baker). Peter Pett the son of John was summoned from his place of residence, then at Harwich to work on the King’s Ships at Portsmouth, and in 1543 was granted a wage and fee for life (vadium et feodum). The authority for the letters patent not being by the usual Writ of Privy Seal, but ‘Per Ipsum Regent’, i.e, by ‘direct motion of the King’, Henry VIII'th. 
On the 23rd April 1548 Robert Holborn, Smyth and Bull received similar Patents, the very fact of which should be considered of some significance, and it was added as Shipwrights they should instruct others, by reason of their long and good service.
== Modern shipbuilding ==
Design work may be conducted using a Ship model basin.
Modern shipbuilding makes considerable use of prefabricated sections; entire multi-deck segments of the hull or superstructure will be built elsewhere in the yard, then lifted into place.
NAICS: NAICS_Code1:=33661