ship form nomenclature & principal views lines & offsets coefficients of form
TRANSCRIPT
Ship FormShip Form
Nomenclature & Principal Views
Lines & Offsets
Coefficients of Form
Ship DimensionsShip DimensionsLength Overall (LOA)
After Perpendicular
Forward Perpendicular
Designed Waterline Length (DWL)
Length Between Perpendiculars (LBP)
Afterbody (STERN)
Forebody (BOW)
Designed Waterline Plane
Beam
Parallel Midbody
DepthMidship Section
Lines Drawings: Lines Drawings: waterlineswaterlines
Length Between Perpendiculars (LBP)
DWLWL2
WL1Baseline
Half-Breadth Plan
Lines Drawings: Lines Drawings: sectionssections
Sta 10 9 8 7 6 4 3 2 1 0
FPAP
Sta 0 (FP)
Sta 2
Sta 4Sta 6
Sta 8
Sta 10 (AP)
Body Plan
Forward SectionsAfter Sections
MIDSHIP SECTION
Section NomenclatureSection Nomenclature
Baseline
DWL
Freeboard
Draft
Depth
Deadrise
BeamHalf-breadth
Camber
Flair Tumblehome
Lines Drawings: Lines Drawings: buttocksbuttocks
DWL
Sheer Plan
Centerline Plane
BP1
BP3BP2
BP1
DWL PLANE
Butt 1
Butt 2Butt 3
DWL
Sheer & CamberSheer & Camber
Sheer Plan
Centerline Plane
BP1
DWL PLANE
Camber
Sheer
Lines DrawingsLines Drawings
Three sets of drawings define the hull shapeHalf-Breadth Plan
Body Plan
Sheer Plan
BP1
OffsetsOffsets
Ships lines may be represented numerically in a table For example
Sta No. Half-breadth @ 30’ (DWL)
Half-breadth @ 25 ‘
Half-breadth @ 20’
… etc. Half-breadth @ Baseline
0 (FP) 16 12 10 4
2 35 33 30 6
4 50 48 45 40
5 () 50 50 48 45
6 50 48 45 40
8 45 42 35 10
10(AP) 40 32 15 0
OffsetsOffsets
Half-breadths for different WL’s at a given station may be used to determine the A of that station
Sta No. Half-breadth @ 30’ (DWL)
Half-breadth @ 25 ‘
Half-breadth @ 20’
… etc. Half-breadth @ Baseline
0 (FP) 16 12 10 4
2 35 33 30 6
4 50 48 45 40
(DWL)30’
25’
20’
15’
10’
5’
(BL) 0’
h= 5B1 = 35
B2 = 33A1= ½ (35+33) x 5 = 170
A2
A3
A4
A5
A6
Hull VolumeHull Volume Section Areas define hull shape Volumes between sections summed to determine displacement
volume,
Midship Section (Station 5)
Area below DWL
Section Volume V5 = ½ (A5+A4) x d
OffsetsOffsets
Likewise, waterplane areas may be calculated from Offset tables
Sta No.
½ -brth @ 30’
½ -brth @ 25’
0 (FP) 16 12
2 35 33
4 50 48
5 () 50 50
6 50 48
8 45 42
10(AP) 40 32
Sta. 10 9 8 7 6 5 4 3 2 1 0
NOTE: The above is distorted because the frame spacing (probably 60’ is not at the same scale as the half-breadths. (Plot to scale below.)
Other Hull Form Dimensions
Besides areas & volumes, hull form determines the location of other critical dimensions.
The centroid (geometric center) of the underwater portion of the hull is the Center of Buoyancy
KBLCBB
The vertical location of B is measured from the keel (KB). The Longitudinal Center of Buoyancy (LCB) is measured
from the Forward Perpendicular The location of B changes with draft (displacement).
Other Hull Form Dimensions
Besides areas & volumes, hull form determines the location of other critical dimensions.
The centroid of the waterplane area is the Center of Floatation (F)
Its location (distance from the fwd perpendicular – LCF) is also a function of displacement
LCF
F
Other Hull Form Dimensions
Besides areas & volumes, hull form determines the location of other critical dimensions.
The distribution of waterplane area determines the Metacentric Radius (BM)
The Center of Buoyancy moves along this arc as the ship rolls
With KB known, the Metacentric Height (KM) becomes an important parameter in stability calculations.
M
B
K
Waterplane Area
Hydrostatic CurvesHydrostatic Curves
27
26
25
24
23
27
26
25
24
23
681800268279
31.1
31.05
31.1
31.2
278
277
276
275
274
267
266
1700
1600
67
66
19000
18000
17000
16000
15000
65
MEAN DRAFT
(FT).
KM
(FT)
LCF (AFT FP)
(FT)
LCB (AFT FP)
(FT)
MT1
(FT-TON)TPI
DISPL in S.W.
(L.TONS)
MEAN DRAFT
(FT)
Block Coefficient: CB = / (L x B x T)
Hull Volume, (under DWL)
Coefficients of FormCoefficients of Form
AP
FP
L (along DWL}Beam, B
Draft, T
Block Volume, L x B x T
Coefficients of FormCoefficients of Form
Prismatic Coefficient: CP = / (A x L)
Hull Volume, (under DWL)
Midship Section Area, A
Prism Volume, (A x L)
Coefficients of FormCoefficients of Form
Midship Section Coefficient: CM = A / (B x T)Beam, B
Draft T A
Rectangle, B x T
Same B & T smaller CM
Note that CM = CB / CP
COF’s are used in the early stages of design to compare characteristics of new design with existing types for estimating performance