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LECTURE LAYOUT

LECTURE LAYOUT. Definition Developments of container ship concept Aspects of container ship design Main dimensions: length, breadth, depth, draft Containers Container stowage and securing Hullform Stability. DEFINITION.

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LECTURE LAYOUT

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  1. LECTURE LAYOUT • Definition • Developments of container ship concept • Aspects of container ship design • Main dimensions: length, breadth, depth, draft • Containers • Container stowage and securing • Hullform • Stability Container Ships

  2. DEFINITION • Containerisation can be considered as a total transportation concept. • The cargo is handled in a utilised form suitable for carriage by sea, road, rail and inland waterways. • Container ship is the seaborn link in the chain. • Containerisation offers a true door to door service. Container Ships

  3. Container Ships

  4. DEVELOPMENT OF CONTAINER SHIP CONCEPT • The first container ships were converted from tankers to carry unitised cargo. • After the developments container ships became • complex, • highly specialised vessels to maximise the benefits to be gained from high cargo handling rates and reduced port time. Container Ships

  5. DEVELOPMENT OF CONTAINER SHIP CONCEPT • The design philosophy has changed from its early form because of: • the changes in the world economy • changes in the trading pattern, • major world political events. Container Ships

  6. DEVELOPMENT OF CONTAINER SHIP CONCEPT • The first container ships had low carrying capacity, because the origin ships were designed to carry bulk cargoes. • The development of specialised container carrying vessels resulted in increases in container capacity for a given volume. Container Ships

  7. DEVELOPMENT OF CONTAINER SHIP CONCEPT • The first ships were carrying around • 1200 TEU (twenty-foot equivalent units) • with the service speed 22 knots. • The first large container ship were designed in the late 1960’s. • The size and speed of the ships increased to take the advantage of the economy. Container Ships

  8. DEVELOPMENT OF CONTAINER SHIP CONCEPT • The large ones upto • 3000 TEU • were powered by twin or triple screw steam or diesel plant • to give service speed of around 26 knots. • After a number of years of successful operation these vessels were badly hit by rising fuel coasts. Container Ships

  9. DEVELOPMENT OF CONTAINER SHIP CONCEPT • Many of the vessels were re-engined to single screw diesel plant. • The reduction in speed resulted in • fuller forms • with the associated advantage of the vessels being able to carry • required capacity with much reduced main dimensions. Container Ships

  10. ASPECTES OF CONTAINER SHIP DESIGN • A container ship can be • a pure container carrier, • a container/RoRo carrier, • a general cargo vessel with a container carrying capability. • A container ship can carry: • a cargo handling equipment or not. Container Ships

  11. ASPECTES OF CONTAINER SHIP DESIGN • The cargo securing equipment can be different types. • Modern cargo vessels have container carrying facility but restricted by: • small hatch area/deck area ratio, • deck stowage resulted from stability consideration, • relatively low ballast of vessels can be another restriction. Container Ships

  12. ASPECTES OF CONTAINER SHIP DESIGN • The design of pure container ships is based on the cargo unit to be carried. • The dimensions, hullform and general layout being developed to maximise the capacity. • Different cargo securing equipment are used to minimise the risk of cargo damage or loss. Container Ships

  13. ASPECTES OF CONTAINER SHIP DESIGN • A pure container vessel can be a • deep sea vessel, • feeder vessel to provide a container distribution service • A modern deep see vessel has a capacity of • 2500+ TEU • with a service speed of 18-24 knots. • Feeders have the smaller capacity • around 500-1000 teu • 16-18 knots. Container Ships

  14. ASPECTES OF CONTAINER SHIP DESIGN • The large vessels operate on well defined liner route with land based cargo handling equipment. • On the other hand feeders are usually operate between the ports without proper shore based equipment, so have cargo handling equipment. Container Ships

  15. MAIN DIMENSIONS • The main dimensions of container ships are based on the physical size of the containers to be accommodated. • For a specified container capacity, the dimensions of the vessel will be determined by the number of bays, rows and tiers. • Dimensions also depend on the navigational futures such as the Panama canal etc. Container Ships

  16. MAIN DIMENSIONS Container Ships

  17. LENGTH • Length of a container ship can be calculated by adding: • length of the cargo space, • length of the machinery space, • length of the fore peak space, • length of the aft peak space. Container Ships

  18. LENGTH Container Ships

  19. LENGTH • The length of the cargo space is a function of: • number of container bays, • the length of the containers, • required clearances to accommodate the container securing device, • necessary allowance for structural members should be taken into account. • Cargo handling equipment such as cranes should be calculated in cargo space length. Container Ships

  20. LENGTH • For preliminary design work, it can be assumed that the length required for each container is (l+1.5) m where l is length of a container (Munro-Smith, 1975) by making allowances for clearance and cross-ties. The LBP of the ship is the sum of the container portion, engine-sterntube and portion forward. Thus: Container Ships

  21. LENGTH LBP = Lc + Le + Lf + LBCC where Lc = Container portion = Nx.(l+1.5) Nx = Number of containers in the length. Le = Length of engine room and after peak tank Lf = Length of fore peak tank. LBCC = Length between most forward cargo hold and collision bulkhead. Container Ships

  22. LENGTH • As a first approximation • the length of the aft peak tank can be taken as 3.5% of LBP. • The length of fore peak tank can be taken as 5% LBP and • length of space forward of container length can be taken as 10% LBP. LBP=0.035 LBP+Le+LC+0.1 LBP+0.05 LBP Container Ships

  23. BREADTH • Breadth is a function of the size of the container units and calculated using the number of container rows. • The gaps between containers depend on the type of stowage equipment. • Breadth is very important to the stability. It is great concern in the design and operation of container ships then any other vessel type. Container Ships

  24. BREADTH • Containers have a standard width of 2.43 m. However, each container requires an allowance for clearance, guides, etc. of about 240 mm (Munro-Smith, 1975) so that each container requires a width of 2.67 m. Thus the number of rows (Ny) cells located transversely in the ship require 2.67 Ny m. Since the width available for containers is about 80 percent of the ship's breadth B, then Container Ships

  25. BREADTH 0.80 B = 2.67 Ny B = 3.34 Ny Ny : Number of tiers of containers in holds. Container Ships

  26. BREADTH Container Ships

  27. VISION Container Ships

  28. DEPTH • It is a function of the size of the container unit with the vertical gaps between the adjacent containers and the height of the tank top in the holds. • The number of tiers of containers to be carried in the hold will be dependent on the proportion of the total capacity of the vessel to be carried under the deck. Container Ships

  29. DEPTH • The rate of under container numbers is around 40-60 % of the total capacity. • Container ships are associated with large freeboard and light loaded drafts. • The light draft is due to the low density of the cargo . Container Ships

  30. DEPTH • This results low displacement according to the physical size of the vessels. • Container ships are deep vessels to accommodate the under deck stowage results in the large freeboard. Container Ships

  31. DEPTH The depth of the ship is in generally controlled by the number of containers to be carried vertically. Thus: D=Nz H + DB where Nz = Number of tiers of containers in holds H = Height containers DB = Depth of double bottom. Container Ships

  32. CONTAINERS • The most common container sizes are 20 and 40 foot ISO standard containers. • There are some other container sizes which are not commonly used. • The problem of the container ship design occurs if the different size of containers should be carried. Container Ships

  33. CONTAINERS Container Ships

  34. CONTAINER STOWAGE AND SECURING • In the holds usually cell guides system is used for stowage and securing. • The system reduces the chance of container damage and speeds up the loading and unloading process. Container Ships

  35. CONTAINER STOWAGE AND SECURING • A typical cell guide system consists of groups of four vertical guides constructed from steel angle bars into which the containers are lowered running the full depth of the vessel from hatch coaming level down to the top tank. Container Ships

  36. Container Ships

  37. CONTAINER STOWAGE AND SECURING Container Ships

  38. CONTAINER STOWAGE AND SECURING • The tolerance into the guides must be small thet shifting of the containers is minimised and that the container spreader can be easily engaged when removing containers. • With this system fastening of the individual containers is unnecessary as all of the static and dynamic forces generated by the containers are transmitted directly into the ship structure by the cell guide members. Container Ships

  39. CONTAINER STOWAGE AND SECURING • There are leading equipment on top of the cell guides in both the longitudinal and transverse directions. • The above deck containers are affected by static and dynamic forces. Container Ships

  40. CONTAINER STOWAGE AND SECURING • These forces limit the securing equipment and number of tiers usually 3 or 4 tires are used. • Twist locks and lashing roads are commonly used above deck securing equipment. Container Ships

  41. CONTAINER STOWAGE AND SECURING Container Ships

  42. CONTAINER STOWAGE AND SECURING Container Ships

  43. HULLFORMS • Afterbodies of container ships are generally characterised by wide transom stern which provide aided stability, increased hold volumes and increased deck areas. • This increases in powering due to large wetted surface area, hence frictional resistance and the increased tendency to slam. Container Ships

  44. Container Ships

  45. HULLFORMS • Another disadvantage of this, flat sections above the propeller will cause vibration. • The fore body will have a bulb to promote the cancellation of the bow wave. This reduces wave making resistance. • Fore body will usually be V shaped in order to improve stability and increase deck area and underdeck container capacity. Container Ships

  46. STABILITY • The stability of container ships is perhaps the most important aspect of their design. • Vertical centre of gravity is very high because of above deck containers, therefore container ships have to be operated with some amount of ballast. • In order to minimise the amount of ballast the heavier containers can be carried in the bottom tiers and the lighter or empty ones being carried on-deck, then VCG is reduced. Container Ships

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