Aug 312013
 
ship
The ship isa special construction, watertight, andableto floaton the waterto movein one direction would,with asteady speedwith aspecific purpose
To be fit for purpose a ship must be able to operate safely and reliably.
Thata ship can safely navigate and accom plishmission for which it was built it must have certaiqualities.
Nautical qualitiesof any shipare:
The ship must do all economically, safely, reliably and with the minimum size of crew

Classification societies
Classification societies are becoming increasingly involved in the classification of naval vessels. Typically they cover the ship and ship systems , including stability, watertight integrity, structural strength, propulsion, fire safety and life saving. They do not cover the weapon systems themselves but do cover the supporting systems. A warship has to be ‘fit for service’ as does any ship. The technical requirements to make them fit for service will differ, as would the requirements for a tanker and for a passenger ship. In the case of the warship the need to take punishment as a result of enemy action, including shock and blast, will lead to a more rugged design. There will be more damage scenarios to be considered with redundancy built into systems so that they are more likely to remain functional after damage.
The involvement of classification societies with naval craft has a number of advantages . It means warships will meet at least the internationally agreed safety standards to which merchant ships are subject. The navy concerned benefits from the world wide organization of surveyors to ensure equipment , materials or even complete ships are of the right quality.
There are many classification societies which co-operate through the International Association of Classification Societies (IACS) (www.iacs.org.uk)
American Bureau of Shippingwww.eagle.org
Bureau Veritaswww.verislar.com
China Classification Society   www.ccs.org.cn
Det Norske Veritaswww.dnv.com
Germanischer Lloyd: www.GermanLloyd.org
Korean Register of Shippingwww.krs.co.kr
Lloyds Register of Shippingwww.lr.org
Nippon KaijiKyokaiwww.classnk.or.jp
RegistroItalinoNavalewww.rina.it
Russian Maritime Register of Shippingwww.rs-head.spb.ru

Main Dimension
The hull form of a ship may be defined by a number of a dimensions and terms which are often referred to during and after building the vessel. An explanation of the principal terms is is given below.
Lightweight: this is the weight of the ship it self when complety empty, with boilers topped up to working level. It is made up of steel weight, wood and outfit weight and machinery weight.
Deadweight: this is the weight that a ship carries. It can be made up of oil fuel, fresh water, stores, lubricating oil, water ballast, crew and effects, cargo and passengers.
Displacement:this is the weight of the volume of water that the ship displaces. Displacement is lightweight  (LWL)+deadweight(DWT). The lightweight will not change much during the life of a ship and so is reasonably constant .the deadweight however will vary, depending on hoe much the ship is loaded.
Freeboard: the vertical distance measured at the ship’s side between the summer load line (or service draft) and the freeboard deck. The freeboard deck is normally the uppermost complete deck exposed to weather and sea which has permanent means of closing all openings, and below which all openings in the ship’s side have watertight closing.
After Perpendicular (AP): a perpendicular drawn to the waterline at the point where the aft side of the rudder post meets the summer load line. Where no rudder post is fitted it is taken as the centre line of the rudder stock.
Forward Perpendicular (FP): a perpendicular drawn to the waterline at the point where the foreside of the stem meets the summer load line.
Length Between Perpendiculars (LBP): the length between the forward and aft perpendiculars measured along the summer load line.
Amidship: a point midway between the after and forward perpendiculars.
Length Overall (LOA): length of vessel taken over all extremities. Forward the point may be on the raked stem or on a bulbous bow.
Length on the waterline (LWL):is the length on the waterline, at which the ship happens to be floating, between the intersections of the bow and after end with the waterline. If not otherwise stated the summer load (or design) waterline is to be understood.
Base Line: a horizontal line drawn at the top of the keel plate. All vertical moulded dimensions are measured relative to this line.
Moulded Beam: Measured at the midshipsection is the maximum moulded breadth of the ship.
Moulded draft:measured  from the base line to the summer load line at the midship section.
Moulded depth: measured from the base line to the heel of the upper deck beam at the ship’s side amidship.
Extreme Beam: the maximum beam taken over all extremities.
Extreme Draft: taken from the lowest point of keel to the summer load line. Draft marks represent extreme drafts.
Extreme Depth: depth of vessel at ship’s side from upper deckto lowest point of keel.
Half Breadth: since a ship’s hull is symmetrical about the longitudinal centre line, often only the half beam or half breadth at any section is given.

ship constructionprincipal lineShip construction process

  • Contract Shipping: sign the contract between the ship owner and the shipbuilder
  • Design & Plan: design the ships using design programs such usTribon, Autocad etc.
  • Pretreatment: steel surface treatment for processing.
  • Cutting: cut the pre-treated steel according to the drawing
  • Assembly: assembly the cut and processed of piece assembly, subblock assembly and block assembly
  • Pre-outfitting: the installation of various pipes, electrical wires and device at the internal and external parts of a block that is already assembled
  • Outfitting: install various ship equipment
  • Painting: the elimination of foreign substances generated in the connection part during loading, and the painting of the steel surface.
  • Pre-erection: the enlargement of a block by gathering 2-3 blocks on which painting has already been completed around the dock.
  • Erection: the welding of the enlarged blocks, both automatically and manually, at the dock, thus making the form of the ship.
  • Launching: the floating of a ship whose form has been made throught welding, and whose painting is completed
  • Sea Trial: a trial at sea (of criteria such as speed, fuel consumption, etc.) as agreed in the contract.
  • Naming: an event to name a ship whose construction has been completed
  • Delivery: deliver the completed ship to the ship owner

 

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