Ship tecnic Sharif university Lecture 3

8/4/2019 Ship tecnic Sharif university Lecture 3

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Chapter 3

BASIC DEFINITONS AND SHIPGEOMETRY


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BASIC DEFINITONS

Main parts of a typical ship


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Hull: The structural body of a ship including shell plating, framing,

decks and bulkheads. Afterbody : That portion of a ships hull abaft midships.

Forebody: That portion of a ships 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


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Design Waterline (DWL) orLoad Waterline (LWL) : The waterline atwhich 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 theships hull.

After Perpendicular (AP) : The vertical line at the point of intersectionof the LWL and the centerline of the rudderstock.

Midships : The point midway between the forward and afterperpendiculars.


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Deck Camber : The rise of the deck of the ship in goingfrom the side to the centre. In older ships the camber curveused to be parabolic but in modern ships straight line cambercurves are used or there may be no camber at all on decks.

Bilge Radius : The radius of the circular arc forming thebilge.

Flat of Keel (Half Siding) : The width of flat bottom plating

on each side of the centre girder.


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Deadrise (Rise of Floor) : The amount by which the line of the outerbottom plating amidships rises above the baseline. Therefore, it is thedifference in height between the baseline and the point where the straight

line through the bottom flat surface intersects the vertical line through theside of the moulded surface at its widest point.

Tumblehome : The amount the top of the side shell slopes back toward thecenterline between the point of widest breadth and the deck at side

Parallel Middle Body : The portion of the ship over which the midshipsection remains unchanged. In this part of the ship water lines and buttockshave no curvature; that is, all the fore and aft lines are


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Length of Waterline (LWL) : The waterline at which the ship willfloat when fully loaded .

Length Overall (LOA) : The total length of the ship from one end tothe other, including bow and stern overhangs.

Length Between Perpendiculars (L BP) : The distance measuredparallel to the base at the level of the design waterline from the afterperpendicular to the forward perpendicular.

Length Overall Submerged (LOS) : The total submerged length ofthe ship from one end to the other, including the bulbous bow.


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Length of Parallel Middle Body (L P) : The length over which themidship section remains unchanged.

Length of Entrance (L E) : The length from the forwardperpendicular to the forward end of parallel middle body, ormaximum section.

Length of Run (L R) : The length from the section of maximum areaor the after end of parallel middle body to waterline termination orother designated point on the stern.

Moulded Beam or Breadth (B) : The distance from the inside ofplating on one side to a similar point on the other side measured atthe broadest part of the ship.


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Maximum Beam or Breadth (B M) : Extreme beam (breadth), fromoutside to outside of the shell plating.

Breadth at Loaded Waterline (B WL) : Maximum moulded breadthat the loaded waterline.

Draught (T) : The vertical distance from the waterline at any point onthe 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 thebaseline to the underside of the plating of the main deck.


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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 thedraught at any point along the ship.

Moulded Displacement : The displacement of a ship based on mouldeddimensions

Total Displacement : Moulded displacement modified by adding thethickness of shell plating and the volume of appendages.

Wetted Surface : The area of the underwater hull and appendages,measured in square meters.


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Displacement

The weight of water that would displaced by the volume of the hullmeasured on the outer surface of the shell plating below the waterline.Displacement tonnage of a vessel can be obtained directly fromArchimedes principle by multiplying its underwater volume by the

density of water.


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Light shipThe lightweight tonnage of a ship is the sum of all fixed weights, i.e.

ship hull, machinery, outfit and permanent equipment.

LS=WS+WM+WO

DeadweightThe difference between the displacement and the lightweight is thedeadweight tonnage which is the sum of the weight of cargo, fuel,lubricating oil, fresh water, stores, passengers and baggage, crew andtheir effects.

DWT=WC+WF+WLO +WFO + WPAS +WLUG+ WCREW+ WSTORE


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TEU/FEUContainer Ships are designed for stowage of containers in verticalstacks or cells either within the hold of the vessel, on deck, or acombination 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.


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Cubic Capacity

Tank ships are described in terms of oil carrying capacity. Barrel (bbl)

is the standard liquid cargo unit of measurement and one barrelconsists of 42 gallons (5.515 cubic feet, 0.156 cubic meter). One ton offuel 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 incubic 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 is the maximum space available for the cargo within aship's hold in cubic meter, incorporating all volume inside the shellplating of the hull and to the underside of the upper deck plating. GrainCubic occupies a larger cargo volume than the ship's Bale Cubic rating.


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Tonnage Measurement

Gross tonnage is the capacity of the spaces in theship's hull and of the enclosed spaces above thedeck 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 propulsionmachinery.


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Representing the Hull Form


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The Half-Breadth Plan


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The Sheer Plan


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The Body Plan


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The Body Plan


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Ship Type


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Tanker


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Tanker


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Passenger ship


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Aircraft carrier


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Small Water-plane Area Twin-Hull (SWATH)

3) SWATH


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3) SWATH(SMALL WATERPLANE AREA TWIN HULL)

.

.


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Ferry (Catamaran, or SWATH)


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Container Ship


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Container Ship


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Hydrofoil Craft


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Ordinates Drawing of A Plane-Hull Craft


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Deaedrise Angle Trim Angle

Step Spray Srake


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Research Vessel TRITON

( )

TRITON


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TRITON

TSL-F


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TSL-F

.

:


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: )-: I) )-: II)

)-: III)

Model Test


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TSL_F


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END

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Ship tecnic Sharif university Lecture 3