8/3/2019 Scheepsbouw
1/4
Basic design of shipBasic design ofship
Dimensions
Cargo carrying capacity
Length minimized (longitudinal bending stresses)
Breadth (stability influence on speed)
Depth (reduction longitudinal bending stresses area of operation)
Displacement
Lightweight (= as low as possible) + deadweight
Stability Sufficient all possible conditions of loading
Important:
o Freeboard
o Sheer
o Weight distribution
Propulsive characteristics & hull form
Attain required speed Hull minimum resistance to motion
Service speed = average speed at sea with normal service power and loading under
average weather conditions (80 90 %)
Trial speed = average speed obtained using maximum power over a measured course
in calm weather with a clean hull (friction) and specified load condition
General arrangement
Co-operation with owner
Efficient working of vessel
Structural details
Classification societys
Owners requirements
8/3/2019 Scheepsbouw
2/4
Ship dimensions and formsShip dimensions and forms
Ship dimensions
After perpendicular (AP) : perpendicular to waterline where aft side of rudder postmeets summer load line
Forward perpendicular (FP) : perpendicular to waterline where foreside of stem meets
summer load line
Mean perpendicular (MP) : perpendicular to waterline halfway between AP and FP
Length between perpendiculars (LBP) : length between AP and FP measured along
summer load line
Amidships: point midway AP and FP
Length Overall: length of vessel over all extremities
Base line: horizontal line at top of keel plate (vertical moulded dimensions measured
relative to this line) Moulded dimensions: inside of plating
Moulded beam
Moulded draft
Moulded depth
Extreme beam
Extreme draft
Extreme depth
Half breadth
Freeboard: vertical distance at ships side between summer load line and freeboard
deck Sheer: curvature of decks in longitudinal direction
Camber / round of beam: curvature of decks in transverse direction
Rise of floor / deadrise: rise of bottom shell plating line above base line
Half siding of keel: horizontal flat portion of bottom shell to port or starboard (useful
when dry-docking
Tumblehome: inward curvature of side shell above summer load line
Flare: outward curvature of side shell above waterline
Stem rake: inclination of stem line from vertical
Keel rake: inclination of the keel line from the horizontal
Tween deck height Parallel middle body: length over which midship section remains constant in area and
shape
Entrance: immersed body of vessel forward parallel middle body
Run: immersed body aft parallel middle body
8/3/2019 Scheepsbouw
3/4
Coefficients
Water-plane coefficient (Cw)
o Fullness of water plane
o
Low Cw => fine ends & high Cw => fuller endso High Cw improves stability & handling behaviour in rough conditions
Midship section coefficient (Cm)
o Fullness of underbody
o Low Cm => cut-away mid-section & high Cm => boxy shape section
Block coefficient / coefficient of fineness (Cb)
o High Cb => full forms
o Low Cb => fine shapes
Prismatic coefficient (Cp)
o Evaluate distribution of volume of underbody
o
Low Cp => full mid-section and fine ends & high Cp => fuller ends
Line plans
Impression of vessel => clear image of exact geometrical shape
Shape vary in height, length and breadth => transverse & 2 longitudinal plans
perpendicular to one another
Ordinates / stations
o Vertical
o Transverse direction
o Usually 20o Centre of rudder stock = ordinate 0
o Combination => frame plan
Waterlines
o Horizontal
o Design water line = water line at level of immersion in full cargo
o Baseline = waterline 0
o Combination => waterline model
Verticals / buttock blocks
o Vertical
o Longitudinal directiono Combination => sheer plan
Diagonals / sent-lines
o Longitudinal direction
o On longitudinal plan => curves
o Most common diagonal = bilge diagonal
Mid-ship sectionMid-ship section
Shows transverse sections and principal dimensions, quality & thickness of shell plating, deck
plating, all longitudinal stiffening, transverse frames and web frames, and important data ofequipment
8/3/2019 Scheepsbouw
4/4
SEE BLACKBOARD
Shell expansionShell expansion
Gives information about distribution of different plates of the shell and other details(hull openings)
At each level and each frame number, quality and thickness can be seen
Drawing:
o Basis: centreline of bottom shell at actual length
o Each frame is rectangular to baseline
o Frame spacing at scale apart with length of total developed length (girth) from
keel to rail (as if a rope drawn along the frame)
o Also shows seams & landings and shell openings
Production of steelProduction of steel Steel = alloy of iron and carbon
Carbon percentage varies (0,1 % mild steels, 1,8 % hardened steels
Open hearth process
Uses waste heat by furnace
Directing fumes through a brick checkerwork => heating bricks => same pathway for
introduction of air into furnace => preheated air increases flame temperature
Electric furnaces
Horizontally placed carbon electrodes produce electric arc above container of metal
Now: vertically positioned graphite electrodes
In induction furnace: coil carrying alternating electric current surrounds a container /
chamber of metal => currents induced in the metal => circulation of these currents
produces extremely high temperatures for making alloys of exact composition
Oxygen process
Pure oxygen blown into molten blast furnace iron and scrap => oxygen initiates series
of intensively exothermic reactions including oxidation of impurities
Commercial advantages:
o High production rates
o Less labour
o Steel with low nitrogen content Chemical additions
o Several purposes
Deoxidise metal
Remove impurities
Desired composition
o Amount of deoxidising elements determines quality of steel
Testing of materials
Top Related