Introduction to Marine Technology Ships Main Particulars

Course-5 Introduction to Marine Technology
Ships Main Particulars
Lecturer : Adi Wirawan Husodo, ST, MT
© Adi Wirawan Husodo
2014
Odd Semester 2014/2015
1

References
• Dokkum, K.V., 2003, Ship Knowledge: A Modern Encyclopedia,
Dokmar, Netherland.
2014
2

Definitions
• Length overall : Length of the ship over its extremities.
• Length between perpendiculars : Length from aft
perpendicular (center of rudderstock) to forward
perpendicular.
• Load line length : Length as used in freeboard calculation.
• Beam : Width of the hull, usually inside shell plating.
• Depth : Height from baseline to uppermost continuous deck
at side, inside of plating.
• Draught : The maximal depth underwater, incl. shell plating.
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Definitions (2)
• Perpendiculars : Imaginary lines, perpendicular to the base
line or plane (and the water line).
• Forward perpendicular (Fpp or Fp): this line crosses the
intersection of the water line and the front of the stem.
• Aft perpendicular (App or Ap): This line usually aligns with the
center line of the rudder stock (the imaginary line around which
the rudder rotates).
• The perpendiculars are used when the lines plan is made.
They are the ends of “block” where the underwater part of
the hull fits in.
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Definitions (3)
• Load line : The water line of a ship lying in the water.
• Deck line : Extended line from the upper side of freeboard
deck (or deck covering) at the ship’s side.
• Moulded dimensions : Distance between two points,
measured at inside of shell plating (or outside framing).
• Base line : Top of the flat keel plate.
• Plimsoll mark or Freeboard mark : is a symbol indicating the
maximum immersion of the ship in the water, leaving a
minimal freeboard for safety.
• Circle with a diameter of one foot (0.3048 m), through which a
horizontal line is drawn with is upper edge going through the
center of circle.
• This level (horizontal line) indicates the minimum freeboard in
salat water summer condition.
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5

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6
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http://s0.geograph.org.uk/geophotos/02/98/90/2989045
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Dimensions
• Length between perpendiculars (Lpp or Lbp) : distance
between the Fore and the Aft Perpendicular.
• Length overall (Loa) : the horizontal distance over the
extremities, from stem to stern.
• Length on the water line (Lwl) : horizontal distance between
the points where bow and stern are going through water
plane, at summer mark, less the shell plating (moulded).
• Draught Forward (Tfwd of Tf) : vertical distance between the
water line and the underside of the keel, as measured at the
forward perpendicular.
• Draught at the stern or Draught After (Ta or Taft) : vertical
distance between the water line and the underside of the
keel, as measured at the aft or after perpendicular.
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8

Dimensions (2)
• Trim : the difference between the draught at the stern and the
draught at the stem.
• Trimmed by the head : draught forward is larger than at the
stern.
• Trimmed by the stern : draught aft is larger than at the
forward.
• On even keel (in proper trim) : the both draughts are equal.
• Breadth or beam (Bmld) : the greatest moulded breadth,
measured from side to side at the outside of frames, but
inside the shell plating.
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Dimensions (3)
• Freeboard : distance between the water line and the top of
deck at the side (deck line).
• Summer Freeboard : the distance from the top of the Summer
Load Line or the Plimsoll Mark and the upper edge of the deck
line.
• Air draught : the vertical distance between the water line and
the highest point of the ship.
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10
• Breadth overall : The
maximum breadth of the ship
as measured from the outer
hull on starboard to the outer
hull on port side, including
rubbing bar, permanent
fenders, etc.

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11

Volumes and Weights
• Register Ton
• Register ton is actually a measure of the volume of enclosed spaces
on a ship (not vessel’s mass or weight).
• It used to determine the size of a ship.
• It is based on volume; 1 register ton = 100 cft or 2.83 m3.
• It is an internationally recognized basis for raising taxes from the
shipping industry and setting levels of fees for port dues, towage,
pilotage and canal passages.
• It is also used as a size determiner in both national and international
shipping regulation. For example: ships of 1,600 GRT or more must
have more comprehensive radio equipment than smaller vessel.
• GRT (Gross Register Tonnage), NRT (Net Register Tonnage).
• IMO in 1969 issued the new measurement system (Universal
Tonnage Measurement System – UMS); GT (Gross Tonnage) and NT
(Net Tonnage).
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Volumes and Weights
• Gross Register Tonnage
• Gross Tonnage
• Includes all enclosed spaces (volume below main deck and
enclosed spaces above main deck).
• Net Register Tonnage
• Net Tonnage
• Just enclosed cargo spaces
• NT is derived from the GT by subtracting the volume of space
occupied by : crew, navigation equipment, the propulsion
equipment (partly), workshops, ballast.
• NT may not less than 30% of the GT.
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13

Volumes and Weights
• Gross Register Tonnage
• Gross Tonnage
• Includes all enclosed spaces (volume below main deck and
enclosed spaces above main deck).
• Net Register Tonnage
• Net Tonnage
• Just enclosed cargo spaces
• NT is derived from the GT by subtracting the volume of space
occupied by : crew, navigation equipment, the propulsion
equipment (partly), workshops, ballast.
• NT may not less than 30% of the GT.
• All measurements in moulded dimensions
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14

Volumes and Weights
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15

Volumes and Weights
• Underwater volume or Carene (m3)
• Moulded volume of a ship minus the contribution of the shell,
propeller and rudder.
• Displacement (m3) - 
• Also familiar with the term of Volume of Displacement
• Is the volume of the part of the ship below the water line
including the shell plating, propeller and rudder.
• Is the volume of water displaced by the immersed body of ship
(including the shell plating, propeller and rudder)
• Displacement (ton) - 
• Is the weight of the volume of water displaced by the ship.
• Equal to the total mass of the ship.
Displacement (ton) = volume of displacement (m3) x density of water (ton/m3)
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Volumes and Weights
• Lightship weight (ton) - LWT
• The weight of ship including the regular inventory, but without any cargo, fuel or
crew.
• Regular inventory such as anchors, life saving appliance, LO, paint, etc.
• Deadweight (ton) – DWT
• This is the weight that ship can load until the maximum allowable immersion
(summer load line).
• Or is the ship’s loaded capacity, including bunkers and other supplies necessary for
the ship’s propulsion
• Is a fixed value;
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Form Coefficients
• Define the characteristics of the vessel’s shape below the
design waterline.
• Non-dimensional figures.
• Volume based and area based.
• Area based:
• Water plane coefficient (Cw or )
• Midship coefficient (Cm or )
• Volume based:
• Block coefficient or coefficient of fineness (Cb or )
• Prismatic coefficient (Cp or )
• Vertival prismatic coefficient (Cpv)
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Water plane coefficient (Cw or )
• Ratio of the area of water plane (Aw) and the rectangular plane
bounded by Lpp and breadth moulded (Bmld).
• A large water plane coefficient in combination with a small block
coefficient is favourable for stability (transversal and longitudinal)
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Midship coefficient (Cm or )
• Ratio of the area of the midship section (Am) and the area
bounded by Bmld and T
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Block coefficient (Cb or )
• or coefficient of fineness
• Ratio of the volume of the underwater body () and the
rectangular block bounded by Lpp, Bmld and T.
• A small block coefficient vessel is referred to as “FINE”.
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Block coefficient (Cb or )
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Prismatic coefficient (Cp or )
• The ration of the volume of the underwater body and the
block formed by the area of Midhsip Section (Am) and Lpp.
• Cp is important for the resistance and hence for the necessary
power of propulsion.
• The smaller Cp, the smaller propulsion power.
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2014
Thank You
24

Introduction to Marine Technology Ships Main Particulars

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