BASIC DEFINITONS AND SHIP GEOMETRY Figure illustrates the main parts of a typical ship.
Hull: The structural body of a ship including shell plating, framing, decks and bulkheads. Afterbody : That portion of a ship’s hull abaft midships. Forebody: That portion of a ship’s hull forward midships. Bow : The forward of the ship Stern : The after end of the ship Port :The left side of the ship when looking forward Starboard : The right side of the ship when looking forward Design Waterline (DWL) or Load Waterline (LWL) : The waterline at which the ship will float when loaded to its designed draught. Moulded Surface : The inside surface of the skin, or plating, of a ship. Forward Perpendicular (FP) : The vertical line at the point of intersection of the LWL and the forward end of the immersed part of the ship’s hull. After Perpendicular (AP) : The vertical line at the point of intersection of the LWL and the centerline of the rudderstock. Midships () : The point midway between the forward and after perpendiculars.
Deck Camber : The rise of the deck of the ship in going from the side to the centre. In older ships the camber curve used to be parabolic but in modern ships straight line camber curves are used or there may be no camber at all on decks. Bilge Radius : The radius of the circular arc forming the bilge. Flat of Keel (Half Siding) : The width of flat bottom plating on each side of the centre girder. Deadrise (Rise of Floor) : The amount by which the line of the outer bottom plating amidships rises above the baseline. Therefore, it is the difference in height between the baseline and the point where the straight line through the bottom flat surface intersects the vertical line through the side of the moulded surface at its widest point. Tumblehome : The amount the top of the side shell slopes back toward the centerline between the point of widest breadth and the deck at side Parallel Middle Body : The portion of the ship over which the midship section remains unchanged. In this part of the ship water lines and buttocks have no curvature; that is, all the fore and aft lines are
Principal Dimensions Length of Waterline (LWL) : The waterline at which the ship will float when fully loaded. Length Overall (L OA) : The total length of the ship from one end to the other, including bow and stern overhangs. Length Between Perpendiculars (L BP) : The distance measured parallel to the base at the level of the design waterline from the after perpendicular to the forward perpendicular. Length Overall Submerged (L OS) : The total submerged length of the ship from one end to the other, including the bulbous bow. Length of Parallel Middle Body (L P) : The length over which the midship section remains unchanged. Length of Entrance (L E) : The length from the forward perpendicular to the forward end of parallel middle body, or maximum section. Length of Run (L R) : The length from the section of maximum area or the after end of parallel middle body to waterline termination or other designated point on the stern. Moulded Beam or Breadth (B) : The distance from the inside of plating on one side to a similar point on the other side measured at the broadest part of the ship.
Principal Dimensions Maximum Beam or Breadth (B M) : Extreme beam (breadth), from outside to outside of the shell plating. Breadth at Loaded Waterline (B WL) : Maximum moulded breadth at the loaded waterline. Draught (T) : The vertical distance from the waterline at any point on the hull to the bottom of the ship. Trim : The difference between the draughts forward and aft. Depth Moulded (D) : The vertical distance at amidships from the baseline to the underside of the plating of the main deck. Freeboard (f) : The vertical distance from the waterline to the deck at side. The freeboard is equal to the difference between the depth at side and the draught at any point along the ship. Moulded Displacement : The displacement of a ship based on moulded dimensions Total Displacement : Moulded displacement modified by adding the thickness of shell plating and the volume of appendages. Wetted Surface : The area of the underwater hull and appendages, measured in square meters.
Displacement The weight of water that would displaced by the volume of the hull measured on the outer surface of the shell plating below the waterline. Displacement tonnage of a vessel can be obtained directly from Archimedes’ principle by multiplying its underwater volume by the density of water. Light ship The lightweight tonnage of a ship is the sum of all fixed weights, i.e. hull, machinery, outfit and permanent equipment. LS=WS+WM+WO Deadweight The difference between the displacement and the lightweight is the deadweight tonnage which is the sum of the weight of cargo, fuel, lubricating oil, fresh water, stores, passengers and baggage, crew and their effects. DWT=W C +W F +W LO +W FO + W PAS +W LUG+ W CREW+ W STORE
TEU/FEU Container Ships are designed for stowage of containers in vertical stacks or cells either within the hold of the vessel, on deck, or a combination of the two. Containers are described in "FEU's" or "TEU's". "FEU" is a forty foot long container (Forty foot Equivalent Unit) "TEU" is a twenty foot long container. (Twenty foot Equivalent Unit ) There are six basic types of containers. Refrigerated containers dry bulk containers; rack containers for lumber, etc; automotive containers; livestock containers; collapsible containers for stowing when not in use.
Cubic Capacity Tank ships are described in terms of oil carrying capacity. Barrel (bbl) is the standard liquid cargo unit of measurement and one barrel consists of 42 gallons (5.515 cubic feet, cubic meter). One ton of fuel oil is equivalent to 6.63 barrels. Dry bulk cargo ships may also be described in terms of Cubic Bales or Cubic Grain. Cubic Bales is the space available for cargo measured in cubic feet within a ship cargo hold to the inside of the cargo battens, on the frames and to the underside of the deck beams. Grain cubic isthe maximum space available for the cargo within a ship's hold in cubic meter, incorporating all volume inside the shell plating of the hull and to the underside of the upper deck plating. Grain Cubic occupies a larger cargo volume than the ship's Bale Cubic rating.
Tonnage Measurement Gross tonnage is the capacity of the spaces in the ship's hull and of the enclosed spaces above the deck available for cargo, stores, fuel, passengers, and crew. Net tonnage is the gross tonnage less the spaces used for the accommodation of the ship's master, officers, crew, and the navigation and propulsion machinery.
International Convention on Tonnage Measurement of Ships, 1969 (TONNAGE 69) Length This means 96 percent of the total length on the waterline, at 85 percent of the least molded depth measured from the top of the keel, or the length from the fore side of the stem to the axis of the rudder stock on that waterline, if that be greater Upper Deck The upper deck is the uppermost complete deck exposed to weather and sea, which has permanent means of weathertight closing of all openings in the weather part thereof, and below which all openings in the sides of the ship are fitted with permanent means of weathertight closing. Moulded Depth The moulded depth is the vertical distance measured from the top of the keel to the underside of the upper deck at side. In wood and composite ships the distance is measured from the lower edge of the keel rabbet. Breadth The breadth is the maximum breadth of the ship, measured amidships to the moulded line of the frame in a ship with a metal shell and to the outer surface of the hull in a ship with a shell of any other material.
Passenger A passenger is every person other than: (a) the master and the members of the crew or other persons employed or engaged in any capacity on board a ship on the business of that ship; and (b) a child under one year of age. Cargo Spaces Cargo spaces to be included in the computation of net tonnage are enclosed spaces appropriated for the transport of cargo which is to be discharged from the ship, provided that such spaces have been included in the computation of gross tonnage. Such cargo spaces shall be certified by permanent marking with the letters CC (cargo compartment) to be so positioned that they are readily visible and not to be less than 100 milimeters (4 inches) in height. Weathertight Weathertight means that in any sea conditions water will not penetrate into the ship
Gross Tonnage The gross tonnage (GT) of a ship shall be determined by the following formula: GT = K 1 V where: V = total volume of all enclosed spaces of the ship in cubic metres K 1 = log10 V Regulation 4 Net Tonnage The net tonnage (NT) of a ship shall be determined by the following formula: in which formula (a) the factor shall not be taken as greater than unity
Categorizing Ships Cargo Ships Ships are generally designed for a specific reason. Cargo ships are designed to carry specific cargo and can be distinguished by the type of cargo they carry, especially since the means of handling the cargo is often highly visible.
Categorizing Ships Cargo ships are generally one of the following types: Bulk Cargo such as coal, wheat, cement, grain or any item moved in bulk quantities. Break bulk cargo is cargo that may be affixed to a pallet. Palletized cargo is organized in such a way as to facilitate the loading into the ship. Containerized cargo, is cargo enclosed into a standardized shipping container. Liquid Cargo such as oil, molasses, chemicals are carried in bulk in large tank ships. Roll on/ Roll Off specialized ships.
Categorizing Ships General Cargo Ships A general cargo ship is a ship with open cargo holds loaded vertically through hatches in the upper deck. The holds may be divided by intermediate decks called tween decks.
Categorizing Ships Container Ships
Categorizing Ships Barge Carrying Ships An extension of the container ship concept is the barge-carrying ship. In this concept, the container is itself a floating vessel, usually about 60 feet long by about 30 feet wide, which is loaded aboard the ship in one of two ways: either it is lifted over the stern by a high- capacity shipboard gantry crane, or the ship is partially submerged so that the barges can be floated aboard via a gate in the stern.
Categorizing Ships LASH SHIPS – LASH stand for Lighter Aboard Ship. It is a specialized container ship carrying very large floating containers, or "lighters." The ship carries its own massive crane, which loads and discharges the containers over the stern. SEABEE - Sea-barge, a barge carrier design similar to "LASH" but which uses rollers to move the barges aboard the ship; the self-propelled loaded barges are themselves loaded on board as cargo and are considerably larger than those loaded on LASH ships
Bulk Carriers (bulker) Bulk Carriers carry bulk cargo such as ore, coal, pulp, rock, cement, scrap metal, grain, flour, rice, fertilizers, sugar or any cargo that travels in bulk.
Oil Tankers Crude oil is carried in oil tankers or in bulk and oil carriers (OBO ships).
LPG and LNG Carrier – –Along with the great increase in numbers and size of tankers have come specialized uses of tankers for products other than oil.
Roll-on/Roll-off ships Roll-on/Roll-off (or Ro/Ro) ships are ships that have specially designed ramps to allow cargo to be driven on board. A car carrier is a good example, but roll on / roll off also relates to trucks, ferry type ships and other ships providing landing ramps for the cargo.
Passenger Ships Passenger ships are vessels that carry passengers either on an overnight cruise or day only cruise.
Non-Transport Ship Types Fishing Vessels
Tugs – –The service ships are mostly tugs or towing vessels whose principal function is to provide propulsive power to other vessels.
Research Ships Many universities, oil companies, water resource boards and governments own and operate research ships. Small research ship may provide platforms for any type of oceanographic endeavor and the large research ships
Icebreaker – –Icebreakers are usually wide in order to make a wide swath through ice, and they have high propulsive power in order to overcome the resistance of the ice layer.
Advanced Marine Vehicles
Fast Ship Pentamaran container ship
Hydrodynamic Supported Vessels Hydrofoil configurations can be divided into two general classifications, surface piercing and submerged foil, which describe how the lifting surfaces are arranged and operate Surface-Piercing (Left) & Fully-Submerged (Right) Foil Configurations
Air Supported Vessels An Air Cushion Vehicle (ACV) or hovercraft is a craft that is entirely supported by air pressure, in close proximity to the surface. It is suitable for use over water or land.
WIG is an abbreviation of Wing-In-Ground effect. A WIG craft can be seen as a crossover between a hovercraft and an aircraft. It flies just above the surface, usually the water surface therefore others use the term WISE or WISES (Wing In Surface Effect Ship).