Nomenclature & Principal Views Lines & Offsets Coefficients of Form Ship Form Nomenclature & Principal Views Lines & Offsets Coefficients of Form

Forward Perpendicular Designed Waterline Plane Ship Dimensions Length Overall (LOA) After Perpendicular Forward Perpendicular Designed Waterline Length (DWL) Length Between Perpendiculars (LBP) Beam Designed Waterline Plane Parallel Midbody Afterbody (STERN) Forebody (BOW) Depth Midship Section

Lines Drawings: waterlines DWL WL2 WL1 Baseline Length Between Perpendiculars (LBP) Half-Breadth Plan

Lines Drawings: sections AP FP Sta 10 9 8 7 6 4 3 2 1 0 After Sections Forward Sections Sta 10 (AP) Sta 0 (FP) MIDSHIP SECTION Sta 2 Sta 8 Sta 6 Sta 4 Body Plan

Section Nomenclature Tumblehome Flair Camber Freeboard Depth Beam DWL Half-breadth Draft Deadrise Baseline

Lines Drawings: buttocks DWL DWL PLANE Centerline Plane BP1 BP2 BP3 Sheer Plan Butt 1 BP1 Butt 3 Butt 2

Sheer & Camber Sheer DWL DWL PLANE Centerline Plane Camber BP1 Sheer Plan Camber BP1

Lines Drawings Three sets of drawings define the hull shape Half-Breadth Plan Body Plan Sheer Plan BP1

Offsets 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 50 48 45 40 5 (F) 8 42 10(AP) 32 15

Offsets 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 50 48 45 40 Half-breadths for different WL’s at a given station may be used to determine the AF of that station (DWL)30’ 25’ 20’ 15’ 10’ 5’ (BL) 0’ B1 = 35 h= 5 A1= ½ (35+33) x 5 = 170 B2 = 33 A2 A3 A4 A5 A6

Hull 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

Offsets Likewise, waterplane areas may be calculated from Offset tables Sta. 10 9 8 7 6 5 4 3 2 1 0 Sta No. ½ -brth @ 30’ ½ -brth @ 25’ 0 (FP) 16 12 2 35 33 4 50 48 5 (F) 6 8 45 42 10(AP) 40 32 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 B LCB KB 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. Waterplane Area M B K

Hydrostatic Curves MEAN DRAFT (FT). KM (FT) LCF (AFT FP) (FT) LCB MT1 (FT-TON) TPI DISPL in S.W. (L.TONS) MEAN DRAFT (FT) 27 26 25 24 23 68 1800 268 279 31.1 31.05 31.2 278 277 276 275 274 267 266 1700 1600 67 66 19000 18000 17000 16000 15000 65

Hull Volume,  (under DWL) Coefficients of Form Block Coefficient: CB =  / (L x B x T) AP Beam, B L (along DWL} FP Hull Volume,  (under DWL) Block Volume, L x B x T Draft, T

Coefficients of Form Prismatic Coefficient: CP =  / (AF x L) Hull Volume,  (under DWL) Prism Volume, (AF x L) Midship Section Area, AF

Coefficients of Form AF Midship Section Coefficient: CM = AF / (B x T) Beam, B 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 AF Draft T Rectangle, B x T Same B & T smaller CM