Preliminary ship-design

PRELIMINARY SHIP DESIGN
PARAMETER ESTIMATION

Shi p desig n cal cul ati ons – Sele cti on of M ai n pa rame ters
START
Read : owner’s requirements
(ship type dwt/TEU, speed)
Define limits on L, B, D, T
Define stability constraints
First estimate of main dimensions
Estimate freeboard
=LBTCb (1 + s)
Estimate form coefficients
& form stability parameters
Estimate power
Estimate lightweight
Estimate stability parameters
Estimate required minimum section modulus
Estimate hull natural vibration frequency
Estimate capacity : GRT, NRT
S
Change parameters
No
D = T+ freeboard + margin
No
No
Estimate seakeeping qualities
YesIs D >= T + freeboard
Yes
Yes
Is= Lightweight + dwt
& Is Capacity adequate?
Stability constraints satisfied

1.0 The choice of parameters (main dimensions and coefficients) can be based on
either of the following 3 ship design categories (Watson & Gilafillon, RINA 1977)
A. Deadweight carriers where the governing equation is
( ) tlightweighdeadweightsTBLCB +=+××××=∆ 1ρ
where s : shell plating and appendage displacement (approx 0.5 to 0.8 % of
moulded displacement)
and ρ : density of water (= 1.025 t/m3
for sea water )
Here T is the maximum draught permitted with minimum freeboard. This is also the
design and scantling draught
B. Capacity carriers where the governing equation is
m
s
ur
BDh V
s
VV
DBLCV +
−
−
=′=
1
...
where
D′ = capacity depth in m mm SCD ++=
mC = mean camber [ ]camberparabolicforC.
3
2
=






=
.L.CatCamber:Cwhere2
1 camberlinestraightfor
C
mS = mean sheer ( )










=
=+=
shearaftS
shearfordS
shearparabolicfor
SS
c
faf6
1
BDC = block coefficient at moulded depth
( ) ( )[ ]TTDCC BB 38.01 −−+= [1]
hV = volume of ship in m3
below upper deck and between perpendiculars
rV = total cargo capacity required in m3
uV = total cargo capacity in m3
available above upper deck
mV = volume required for cm , tanks, etc. within hV

sS = % of moulded volume to be deducted as volume of structurals in cargo
space [normally taken as 0.05]
Here T is not the main factor though it is involved as a second order term in BDC
C. Linear Dimension Ships : The dimensions for such a ship are fixed by
consideration other than deadweight and capacity.
e.g.
Restrictions imposed by St. Lawrence seaway
6.10 m ≤ Loa ≤ 222.5 m
Bext ≤ 23.16 m
Restrictions imposed by Panama Canal
B ≤ 32.3 m; T ≤ 13 m
Restrictions imposed by Dover and Malacca Straits
T ≤ 23 m
Restrictions imposed by ports of call.
Ship types (e.g. barge carriers, container ships, etc.) whose dimensions are
determined by the unit of cargo they carry.
Restrictions can also be imposed by the shipbuilding facilities.
2.0 Parameter Estimation
The first estimates of parameters and coefficients is done
(a) from empirical formulae available in published literature, or
(b) from collection of recent data and statistical analysis, or
(c) by extrapolating from a nearly similar ship
The selection of parameters affects shipbuilding cost considerably. The order in
which shipbuilding cost varies with main dimension generally is as follows:
The effect of various parameters on the ship performance can be as shown in the
following table [1]
Speed
Length
Breadth
Depth
Block coefficient

Table: Primary Influence of Dimension
Parameter Primary Influence of Dimensions
Length
Beam
Depth
Draft
resistance, capital cost, maneuverability, longitudinal strength,
hull volume, seakeeping
transverse stability, resistance, maneuverability, capital cost, hull
volume
hull volume, longitudinal strength, transverse stability, capital
cost, freeboard
displacement, freeboard, resistance, transverse stability
2.1 Displacement
A preliminary estimate of displacement can be made from statistical data analysis,
as a function of deadweight capacity. The statistical
∆
dwt
ratio is given in the
following table [1]
Table: Typical Deadweight Coefficient Ranges
Vessel Type Ccargo DWT Ctotal DWT
Large tankers
Product tankers
Container ships
Ro-Ro ships
Large bulk carriers
Small bulk carriers
Refrigerated cargo ships
Fishing trawlers
0.85 – 0.87
0.77 – 0.83
0.56 – 0.63
0.50 – 0.59
0.79 – 0.84
0.71 – 0.77
0.50 – 0.59
0.37 – 0.45
0.86 – 0.89
0.78 – 0.85
0.70 – 0.78

0.81 – 0.88

0.60 – 0.69

where
ntDisplaceme
DWTTotalorDWToC
C
arg
=
2.2 Length
A. Posdunine’s formulae as modified by Van Lammeran :

( ) 3
1
2
2
∆





+
=
T
T
BP
V
V
CftL
C = 23.5 for single screw cargo and passenger ships where V = 11 to 16.5 knots
= 24 for twin screw cargo and passenger ships where V = 15.5 to 18.5 knots
= 26 for fast passenger ships with V≥ 20 knots
B. Volker’s Statistics :
3
,5.45.3
3
13
1
mindisp
mL
sminV
g
V
C
L
→∇
→
∇
+=





−
∇
where C = 0 for dry cargo ships and container ships
= 0.5 for refrigerated ship and
= 1.5 for waters and trawler
C. Schneekluth’s Formulae : This formulae is based on statistics of optimization
results according to economic criteria, or length for lowest production cost.
CVLPP ∗∗∆= 3.03.0
Lpp in metres, ∆ is displacement in tonnes and V is speed in knots
C = 3.2, if the block coefficient has approximate value of
CB = Fn
145.0 within the range 0.48 – 0.85
It the block coefficient differs from the value Fn
145.0 , the coefficient C can be
modified as follows
( ) 5.0145.0
5.0
2.3
+
+
=
Fn
C
C B
The value of C can be larger if one of the following conditions exists :
(a) Draught and / or breadth subject to limitations
(b) No bulbous bow
(c) Large ratio of undadeck volume to displacement

Depending on the conditions C is only rarely outside the range 2.5 to 2.8.
Statistics from ships built in recent years show a tendency towards smaller value
of C than before.
The formulae is valid for 1000≥∆ tonnes, and
nF between 0.16 to 0.32
2.3 Breadth
Recent trends are:
L/B = 4.0 for small craft with L ≤ 30 m such as trawlers etc.
= 6.5 for L ≥ 130.0 m
= 4.0 + 0.025 (L - 30) for 30 m ≤ L ≤ 130 m
B = L/9 + 4.5 to 6.5 m for tankers
= L/9 + 6.0 m for bulkers
= L/9 + 6.5 to 7.0 m for general cargo ships
= L/9 + 12 to 15 m for VLCC.
or B = L/5 – 14m for VLCC
B = m
Dwt
2828.0
1000
78.10 





2.4 Depth
For normal single hull vessels
5.2/55.1 ≤≤ DB
DB / = 1.65 for fishing vessels and capacity type vessels (Stability limited)
= 1.90 for dwt carries like costers, tankers, bulk carriers etc. such vessels
have adequate stability and their depth is determined from the hull
deflection point of view. (3)
D =
5.1
3−B
m for bulk carriers (5)
Recent ships indicate the following values of DB /

DB / = 1.91 for large tankers
= 2.1 for Great Lakes ore carriers
= 2.5 for ULCC
= 1.88 for bulk carriers and
= 1.70 for container ships and reefer ships
2.5 Draught
For conventional monohull vessels, generally
75.3/25.2 ≤≤ TB
However, TB / can go upto 5 in heavily draught limited vessels.
For ensuring proper flow onto the propeller
[ ]BC
T
B 5.7625.9 −≤
Draught – depth ratio is largely a function of freeboard :
DT / = 0.8 for type A freeboard (tankers)
( DT / < 0.8 for double hull tankers)
= 0.7 for type B freeboard
= 0.7 to 0.8 for B – 60 freeboard
T = m
dwt
290.0
1000
536.4 





T = 0.66 D + 0.9 m for bulk carriers
2.6 Depth – Length Relationship
Deadweight carriers have a high DB / ratio as these ships have adequate stability
and therefore, beam is independents of depth. In such case, depth is governed by
DL / ratio which is a significant term in determining the longitudinal strength.
DL / determines the hull deflection because b.m. imposed by waves and cargo
distribution.
DL / =10 to 14 with tankers having a higher value because of favourable
structural arrangement.
3.0 Form Coefficients
MPB CCC .=

and WPVPB CCC .=
where Cp : Longitudinal prismatic coefficient
and CVP: Vertical prismatic coefficient
LA
C
M
P
.
∇
=
TA
C
WP
VP
.
∇
=
3.1 Block Coefficients
( )[ ]nB FC −+= −
23.025tan7.0 1
8
1
where
gL
V
Fn = : Froude Number
A. Ayre’s formulae
CB = C – 1.68 Fn
where C = 1.08 for single screw ships
= 1.09 for twin screw ships
Currently, this formulae is frequently used with C = 1.06
It can be rewritten using recent data as
CB = 1.18 – 0.69 L
V
for 0.5 ≤≤
L
V
1.0 ,
V: Speed in Knots and
L: Length in feet
CB = 




 +
26
2014.0 B
L
nF
or
CB = 




 +
26
2014.0
3
2
B
L
nF
The above formulae are valid for 0.48 ≤ CB ≤ 0.85, and 0.14 ≤ Fn ≤ 0.32
Japanese statistical study [1] gives CB for
32.015.0 ≤≤ nF as

3
6.461.398.2722.4 nnnB FFFC +−+−=
3.2 Midship Area Coefficient
CB = 0.55 0.60 0.65 0.70
CM = 0.96 0.976 0.980 0.987
Recommended values of C can be given as
CM = 0.977 + 0.085 (CB – 0.60)
= 1.006 – 0.0056 56.3−
BC
= ( )[ ] 15.3
11
−
−+ BC [1]
Estimation of Bilge Radius and Midship area Coefficient
(i) Midship Section with circular bilge and no rise of floor
( )
π−
−
=
4
..122 TBC
R M
=2.33 (1 – CM ) B.T.
(ii) Midship Section with rise of floor (r) and no flat of keel
( )
8584.0
.122 rBCBT
R M −−
=
(iii) Schneekluth’s recommendation for Bilge Radius (R)
( ) 2
4 BB
L
k
C
BC
R
+
=
Ck : Varies between 0.5 and 0.6 and in extreme cases between 0.4 and 0.7
For rise at floor (r) the above CB can be modified as
( )2
r
B
B
T
TC
C
−
=′

(iv) If there is flat of keel width K and a rise of floor F at 2
B then,
( ) ( )[ ]{ } BTrrFC KBKB
M /4292.0/1 2
22
2
22 +−−−−=
From producibility considerations, many times the bilge radius is taken equal to
or slightly less than the double bottom height.
3.3 Water Plane Area Cofficient
Table 11.V
Equation Applicability/Source
CWP = 0.180 + 0.860 CP Series 60
CWP = 0.444 + 0.520 CP Eames, small transom stern warships (2)
CWP = CB/(0.471 + 0.551 CB) tankers and bulk carriers (17)
CWP = 0.175+ 0.875 CP single screw, cruiser stern
CWP = 0.262 + 0.760 CP twin screw, cruiser stern
CWP = 0.262 + 0.810 CP twin screw, transom stern
CWP = CP
2/3
schneekluth 1 (17)
CWP = ( 1+2 CB/Cm
½
)/3 Schneekulth 2 (17)
CWP = 0.95 CP + 0.17 (1- CP)1/3
U-forms hulls
CWP = (1+2 CB)/3 Average hulls, Riddlesworth (2)
CWP = CB
½
- 0.025 V-form hulls
4.0 Intial Estimate of Stability
4.1 Vertical Centre of Buoyancy, KB [1]
( ) 3/5.2 VPC
T
KB
−= :Moorish / Normand recommend for hulls with 9.0≤MC
( ) 1
1
−
+= VPC
T
KB
:Posdumine and Lackenby recommended for hulls with 0.9<CM
Regression formulations are as follows :
T
KB
= 0.90 – 0.36 CM

T
KB
= (0.90 – 0.30 CM – 0.10 CB)
T
KB
= 0.78 – 0.285 CVP
4.2 Metacenteic Radius : BMT and BML
Moment of Inertia coefficient CI and CIL are defined as
CI = 3
LB
IT
CTL = 3
LB
IL
The formula for initial estimation of CI and CIL are given below
Table 11.VI Equations for Estimating Waterplane Inertia Coefficients
Equations Applicability / Source
C1 = 0.1216 CWP – 0.0410 D’Arcangelo transverse
CIL = 0.350 CWP
2
– 0.405 CWP + 0.146 D’Arcangelo longitudinal
CI = 0.0727 CWP
2
+ 0.0106 CWP – 0.003 Eames, small transom stern (2)
C1 = 0.04 (3CWP – 1) Murray, for trapezium reduced 4% (17)
CI = (0.096 + 0.89 CWP
2
) / 12 Normand (17)
CI = (0.0372 (2 CWP + 1)3
) / 12 Bauer (17)
CI = 1.04 CWP
2
) / 12 McCloghrie + 4% (17)
CI = (0.13 CWP + 0.87 CWP
2
) / 12 Dudszus and Danckwardt (17)
∇
= T
TM
I
B
∇
= L
LM
K
B
4.3 Transverse Stability
KG / D= 0.63 to 0.70 for normal cargo ships

= 0.83 for passenger ships
= 0.90 for trawlers and tugs
KMT = KB + BMT
GMT = KMT – KG
Correction for free surface must be applied over this. Then ,
GM’T = GMT – 0.03 KG (assumed).
This GM’T should satisfy IMO requirements.
4.3 Longitudinal Stability
B
LI
B
LIL
LL
CT
LC
CLBT
BLCI
BMGM
.
23
==
∇
=≅
100..100
...
100
1
22
BLC
LCT
LCCTBL
L
GM
cmMCT
LI
B
LIB
BP
L
==
∇
=
4.5 Longitudinal Centre of Buoyancy (1)
The longitudinal centre of buoyancy LCB affects the resistance and trim of the
vessel. Initial estimates are needed as input to some resistance estimating
algorithms. Like wise, initial checks of vessel trim require a sound LCB estimate.
In general, LCB will move aft with ship design speed and Froude number. At low
Froude number, the bow can be fairly blunt with cylindrical or elliptical bows
utilized on slow vessels. On these vessels it is necessary to fair the stern to
achieve effective flow into the propeller, so the run is more tapered (horizontally
or vertically in a buttock flow stern) than the bow resulting in an LCB which is
forward of amidships. As the vessel becomes faster for its length, the bow must be
faired to achieve acceptable wave resistance, resulting in a movement of the LCB
aft through amidships. At even higher speeds the bow must be faired even more
resulting in an LCB aft of amidships.
Harvald
8.00.4570.9 ±−= FnLCB
Schneekluth and Bestram
FnLCB 9.3880.8 −=
PCLCB 4.195.13 +−=

Here LCB is estimated as percentage of length, positive forward of amidships.
5.0 Lightship Weight Estimation
(a) Lightship weight =
64.0
1000
1128 




 dwt
(4)
(b) Lightship = Steel Weight + Outfil weight + Machinery Weight +
Margin.
5.1 Steel Weight
The estimated steel weight is normally the Net steel. To this Scrap steel weight
(10 to 18 %) is added to get gross steel weight.
Ship type Cargo Cargo cum
Passenger
Passenger Cross Channe
Pass. ferry
( )
weight
Steel×
∆
100 20 28 30 35
For tankers, 18
100
=×
∆
weightSteel
5.1.1 Steel weight Estimation – Watson and Gilfillan
From ref. (3),
Hull Numeral E = 2211 75.085.0)(85.0)( hlhlLTDTBL ∑∑ ++−++ in
metric units where
11 handl : length and height of full width erections
22 handl : length and height of houses.
( )[ ]70.05.01 17 −+= Bss CWW
where sW : Steel weight of actual ship with block 1BC at 0.8D
7sW : Steel weight of a ship with block 0.70
( ) 




 −
−+=
T
TD
CCC BBB
3
8.0
11
Where BC : Actual block at T.

36.1
7 . EKWs =
Ship type Value of K For E
Tanker 0.029 – 0.035 1,500 < E < 40, 000
Chemical Tanker 0.036 – 0.037 1,900 < E < 2, 500
Bulker 0.029 – 0.032 3,000 < E < 15, 000
Open type bulk and
Container ship
0.033 – 0.040 6,000 < E < 13, 000
Cargo 0.029 – 0.037 2,000 < E < 7, 000
Refrig 0.032 – 0.035 E 5,000
Coasters 0.027 – 0.032 1,000 < E < 2, 000
Offshore Supply 0.041 – 0.051 800 < E < 1, 300
Tugs 0.044 350, E < 450
Trawler 0.041 – 0.042 250, E < 1, 300
Research Vessel 0.045 – 0.046 1, 350 < E < 1, 500
Ferries 0.024 – 0.037 2,000 < E < 5, 000
Passenger 0.037 – 0.038 5, 000 < E < 15, 000
5.1.2 From Basic Ship
Steeel weight from basic ship can be estimated assuming any of the
following relations :
(i) ×∞ LWs weight per foot amidships
(ii) ... DBLWs ∞
(iii) )(. DBLWs +∞
To this steel weight, all major alterations are added / substracted.
Schneekluth Method for Steel Weight of Dry Cargo Ship
u∇ = volume below topmost container deck (m3
)
D∇ = hull volume upto main deck (m3
)
s∇ = Volume increase through sheer (m3
)
b∇ = Volume increase through camber (m3
)
uv ss , = height of s hear at FP and AP
sL = length over which sheer extends ( pps LL ≤ )
n = number of decks
L∇ = Volume of hatchways
LLL handb; are length, breadth and height of hatchway

u∇ =
( )
        
LbsD
LLLusBD hblCbBLCssBLCDBL
∇∇∇∇
∑++++ 32ϑ
CBD = ( )BB C
T
TD
CC −
−
+ 14
Where C4 = 0.25 for ship forms with little flame flare
= 0.4 for ship forms with marked flame flare
C2 =
( )
b
CBD
3
2
; C3 = 0.7 CBD
Wst
( )±
= u∇ C1
( )[ ] ( )[ ]4
06.0112033.01 D
D
L
n −+−+
( )[ ] ( )[ ]85.02.0185.105.01 −+−+ D
T
D
B
( )[ ] ( )[ ]98.075.01192.0
2
−+−+ MBDBD CCC
Restriction imposed on the formula :
9<
D
L
, and
C1 the volumetric weight factor and dependent on ship type and measured in 3
m
t
C1 = ( )[ ]62
10110171103.0 −
−+ L 3
m
t
for mLm 18080 ≤≤ for normal ships
C1 = 0.113 to 0.121 3
m
t
for mLm 15080 ≤≤ of passenger ships
C1 = 0.102 to 0.116 3
m
t
for mLm 150100 ≤≤ of refrigerated ships
5.1.3 Schneekluth’s Method for Steel Weight of container Ships
( )[ ] 32
10120002.01093.0 −
−+∇= LW ust
( )
2
1
14
30
12057.01 





+











−+
DD
L
( )[ ]2
2
192.085.002.011.201.01 BDC
D
T
D
B
−+











−+














−+
Depending on the steel construction the tolerance width of the result will be
somewhat greater than that of normal cargo ships. The factor 0.093 may vary between

0.09 and 0 the under deck volume contains the volume of a short forecastle for the
volume of hatchways
The ratio
D
L
should not be less than 10
Farther Corrections :
(a) where normal steel is used the following should be added :
( ) ( ) 











−+−= 121.01105.3%
D
L
LW tsδ
This correction is valid for ships between 100 m and 180 m length
(b) No correction for wing tank is needed
(c) The formulae can be applied to container ships with trapizoidal midship sections.
These are around 5% lighter
(d) Further corrections can be added for ice-strengthening, different double bottom
height, higher latchways, higher speeds.
Container Cell Guides
Container cell guides are normally included in the steel weight. Weight of container
cell guides.
Ship type Length
(ft)
Fixed Detachable
Vessel 20 0.7 t / TEU 1 t / TEU
Vessel 40 0.45 t / TEU 0.7 t / TEU
Integrated 20 0.75 t / TEU -
Integrated 40 0.48 t / TEU -
Where containers are stowed in three stacks, the lashings weigh :
for 20 ft containers 0.024 t / TEU
40 ft containers 0.031 t / TEU
mixed stowage 0.043 t / TEU
5.1.4 Steel Weight Estimations : other formulations
For containce Ships :

374.0712.0759.1
..007.0 DBLW ppst = [K. R. Chapman]
→stW steel weight in tonns
→DBLpp ,, are in metres.
stW = ( )








+





−∗





+ 939.03.800585.0
2
675.0000,100340
8.1
9.0
D
LC
LBD B
[D. Miller]
→stW tonnes
→DBL ,, metres
For Dry Cargo vessels
7
1073.5
0832.0
−
−
= x
st exW
where 3
2
12
B
pp
C
BL
x = [wehkamp / kerlen]








+





= 1002.0
6
2
72.03
2
D
L
D
LB
CW Bst
[ Ccmyette’s formula
as represented by
watson & Gilfillan ]
→stW tonnes
→DBL ,, metres
For tankers :












−∗∗





−+∆=
D
L
B
L
W TLst 7.2806.0004.0009.1αα
DNV – 1972
where
78.0
100
189.0
97.0004.0054.0






∗
∗





+
=
D
L
B
L
Lα






 ∆
∗+=
100000
00235.0029.0Tα for ∆ < 600000 t
3.0
100000
0252.0 




 ∆
∗=Tα for ∆ > 600000 t
Range of Validity :
1410 ≤≤
D
L
75 ≤≤
B
L
mLm 480150 ≤≤
For Bulk Carriers
( )
8.0
4.05.0
2
1697.0 56.1 +
∗





+= B
st
CT
D
B
LW [J. M. Hurrey]





 −
+





+





−=
1800
200
1025.073.0035.0215.1274.4 62.0 L
B
L
B
L
LZWst






−





−∗
D
L
D
L
0163.0146.107.042.2 [DNV 1972]
here Z is the section modulus of midship section area
The limits of validity for DNV formulae for bulkers are same as tankers except
that is, valid for a length upto 380 m
5.2 Machinery Weight
5.2.1 Murirosmith
Wm = BHP/10 + 200 tons diesel
= SHP/17 + 280 tons turbine
= SHP/ 30 + 200 tons turbine (cross channel)
This includes all weights of auxiliaries within definition of m/c weight as part of
light weight. Corrections may be made as follows:
For m/c aft deduct 5%

For twin-screw ships add 10% and
For ships with large electrical load add 5 to 12%
5.2.2 Watson and Gilfillan
Wm (diesel) .]/[12 84.0
wtAuxiliaryRPMiMCRi
i
+= ∑
Wm (diesel-electric) = 0.72 (M CR)0.78
Wm (gas turbine) = 0.001 (MCR)
Auxiliary weight = 0.69 (MCR)0.7
for bulk and general cargo vessel
= 0.72 (MCR)0.7
for tankers
= 0.83 (MCR)0.7
for passenger ships and ferries
= 0.19 for frigates and Convetters
MCR is in kw and RPM of the engine
5.3 Wood and Outfit Wight (Wo)
5.3.1 Watson and Gilfilla
W and G (RINA 1977): (figure taken from [1])

5.3.2. Basic Ship
Wo can be estimated from basic ship using any of the proportionalities given
below:
5.3.3. Schneekluth
Out Fit Weight Estimation
Cargo ships at every type
No = K. L. B., Wo ,tonnes→ L, B → meters
Where the value of K is as follows
Type K
(a) Cargo ships 0.40-0.45 t/m2
(b) Container ships 0.34-0.38 t/m2
(c) Bulk carriers without cranes
With length around 140 m 0.22-0.25 t/m2
With length around 250 m 0.17-0.18 t/m2
(d) Crude oil tankers:

With lengths around 150 m 0.25 t/m2
With lengths around 300 m 0.17 t/m2
Passenger ships – Cabin ships
∑∇= KW0 where ∑∇ total volume 1n m3
33
039.0036.0 mtmtK −=
Passenger ships with large car transporting sections and passenger ships carrying
deck passengers
∑∇= KW0 , where K = 0.04 t/m2
– 0.05 t/m2
BLWo ×α or
1
2
1
20
02
2 B
B
L
LLW
W ×+=
Where suffix 2 is for new ship and 1 is for basic ship.
From this, all major alterations are added or substracted.
5.4 Margin on Light Weight Estimation
Ship type Margin on Wt Margin on VCG
Cargo ships 1.5 to 2.5% 0.5 to ¾ %
Passenger ships 2 to 3.5% ¾ to 1 %
Naval Ships 3.5 to 7%
5.5 Displacement Allowance due to Appendages ( )PPα∆
(i) Extra displacement due to shell plating = molded displacement x (1.005 do
1.008) where 1.005 is for ULCCS and 1.008 for small craft.
(ii) where C = 0.7 for fine and 1.4 for full bossings
d: Propeller diameter.
(iii) Rudder Displacement = 0.13 x (area)9/2
tonnes
(iv) Propeller Displacement = 0.01 x d3
tonnes
.appextext ∆+∆=∆
5.6 Dead weight Estimation
At initial stage deadweight is supplied. However,

PRECFWLODOHFOoC WWWWWWWDwt ++++++= &arg
Where WCargo : Cargo weight (required to be carried) which can be calculated from
cargo hold capacity
WHFO = SFC x MCR x inm
speed
range
arg×
Where
SFC : specific fuel consumption which can be taken as 190gm/kw hr for DE and
215gm/kw hr for 6T (This includes 10% excess for ship board approx )
Range: distance to be covered between two bunkeriy port margin : 5 to 10%
WDO : Weight of marine diesel oil for DG Sets which is calculated similar to
above based on actual power at sea and port(s)
WLO : weight of lubrication oil
WLO = 20 t for medium speed DE
=15 t for slow speed DE
WFW : weight of fresh water
WFW = 0.17 t/(person x day)
WC&E : weight of crew of fresh water
WC&E : 0.17t / person
WPR : weight of provisions and stores
WPR = 0.01t / (person x day)
5.7 Therefore weight equation to be satisfied is
ext∆ = Light ship weight + Dead weight
where
light ship weight = steel weight + wood and out fit weight + machinery weight +
margin.
6.0 Estimation of Centre of Mass (1)
The VCG of the basic hull can be estimated using an equation as follows:
VCGhull = 0.01D [ 46.6 + 0.135 ( 0.81 – CB ) ( L/D )2
]
+ 0.008D ( L/B – 6.5 ), L≤ 120 m
= 0.01D [ 46.6 + 0.135 (0.81 – CB ) ( L/D )2
],
120 m < L

This may be modified for superstructure & deck housing
The longitudinal position of the basic hull weight will typically be slightly aft of
the LCB position. Waston gives the suggestion:
LCGhull = - 0.15 + LCB
Where both LCG and LCB are in percent ship length positive forward of
amidships. The vertical center of the machinery weight will depend upon the
inner bottom height hbd and the height of the engine room from heel, D. With
these known, the VCG of the machinery weight can be estimated as:
VCGM = hdb + 0.35 ( D’-hdb )
Which places the machinery VCG at 35% of the height within the engine room
space. In order to estimate the height of the inner bottom, minimum values from
classification and Cost Guard requirements can be consulted giving for example:
hdb ≥ 32B + 190 T (mm) (ABS)
or
hdb ≥ 45.7 + 0.417 L (cm) Us Coast Guard
The inner bottom height might be made greater than indicated by these minimum
requirements in order to provide greater double bottom tank capacity, meet double
hull requirements, or to allow easier structural inspection and tank maintenance.
The vertical center of the outfit weight is typically above the main deck and can
be estimated using an equation as follows:
VCGo = D + 1.25, L ≤ 125 m
= D + 1.25 + 0.01(L-125), 125 < L ≤ 250 m
= D + 2.50,
The longitudinal center of the outfit weight depends upon the location of the
machinery and the deckhouse since significant portions of the outfit are in those
locations. The remainder of the outfit weight is distributed along the entire hull.
LCGo = ( 25% Wo at LCGM, 37.5% at LCG dh, and 37.5% at amid ships)
The specific fractions can be adapted based upon data for similar ships. This
approach captures the influence of the machinery and deckhouse locations on the
associated outfit weight at the earliest stages of the design.
The centers of the deadweight items can be estimated based upon the preliminary
inboard profile arrangement and the intent of the designer.

7.0 Estimation of Capacity
Grain Capacity = Moulded Col. + extra vol. due to hatch (m3
) coamings,edcape
hatched etc – vol. of structurals.
Tank capacity = Max. no. of containers below deck (TEU) and above dk.
Structurals for holds :
2
1
1 to 2% of mid vol.
Structurals for F. O. tanks : ofto %
4
1
2
4
1
2 mid. Vol.(without heating coils):
ofto %
4
9
2
2
1
2 mid vol. (with heating coils):1% for
cargo oil tanks
Structurals for BW/FW tanks:
2
1
2
4
1
2 to for d.b. tanks non-cemented;
%
4
3
2
2
1
2 to for d.b. tanks cemented;
1 to 1.5 % for deep tanks for FO/BW/PW.
Bale capacity 0.90 x Grain Capacity.
Grain capacity can be estimated by using any one of 3 methods given below as
per ref. MSD by Munro-Smith:
1. Grain capacity for underdeck space for cargo ships including machinery
space, tunnel, bunkers etc.:
Capacity = C1 + C2 + C3
Where
C1 : Grain capacitay of space between keel and line parallel to LWL drawn at
the lowest point of deck at side.
C1 = LBP x Bml x Dmld x C
C : capacity coefficient as given below
CB at 0.85D 0.73 0.74 0.75 0.76 0.77 0.78
C 0.742 0.751 0.760 0.769 0.778 0.787
CB at 0.85D can be calculated for the design ship from the relationship
TdT
dcu
.10
1
=
The C.G. of C1 can be taken as 0.515 x D above tank top.

C2 : Volume between WL at lowest point of sheer and sheer line at side.
C2 : 0.236 X S X B X LBP/2 with centroid at 0.259S above WL at lowest point
of sheer
Where S = sheer forward + sheer aft.
C3 = 0.548 x camber at midship x B x LBP/ 2 with centriod at 0.2365 + 0.381 x
camber at above WL at lowest point of sheer. Both forward and aft calculations
are done separately and added. C2 and C3 are calculated on the assumption that
deck line, camber line and sheer line are parabolic.
II. Capacity Depth DC
DC = Dmld + ½ camber + 1/6 (SA + SF) – (depth of d.b. + tank top ceiling)
Grain capacity below upper deck and above tank top including non cargo spaces
is given as:
LBDC.CB/100(ft3
) 2000 3000 4000 5000 6000 7000 8000
Grain Cap. (ft3
) 2000 3000 4000 5050 6100 7150 8200
III. From basic ship:
C1: Under dk sapacity of basic ship
= Grain cap. of cargo spaces + under dk non-cargo spaces – hatchways.
C2: Under deck capacity of new ship.
C2=
2222
111
1
Bc
BL
CDBL
CDBL
C
−×
Where CB is taken at 0.85 D
If DH : Depth of hold amidships and C9 : cintoroid of this capacity above tank top
then, for
CB = 0.76 at 0.85 D,
1/6(SF + SA)/DH 0.06 0.08 0.10 0.12
C9/DH 0.556 0.565 0.573 0.583
For an increase of decrease of CB by 0.02,
C9/DH is decreased or increased by 0.002.
From the capacity thus obtained, non cargo spaces are deducted and extra spaces
as hatchways etc. are added go get the total grain capacity.

8.0 Power Estimation
For quick estimation of power:
(a) [ ] 5.0
3
0
1000/5813.0 DWT
V
SHP
=
(b) Admirality coefficient is same for similar ships (in size, form, nF ).
BHP
V
AC
93/2
∆
=
Where CoefficentAdmiralityAC =
tonsinntDisplaceme=∆
KnotsinSpeedV =
(c) In RINA, vol 102, Moor and Small Have proposed
LN
CK
L
VH
SHP
B
γ−






−−+∆
=
1500
12)1(400
200
40 233/1
Where RPMN :
onconstructiweldedforfactorcorrectionHullH 9.0: =
.,,:
':
tonsinknotsinVftinL
formulasAlexanderfrombeobtainedToK
∆
(d) From basic ship: If basic ship EHP is known. EHP for a new ship with
similar hull form and Fr. No.- can be found out as follows:
(i) Breadth and Draught correction can be applied using Mumford indices (moor
and small, RINA, vol. 102)

3/23/2 −−
ΘΘ












=
Y
b
n
X
b
n
T
T
B
B
basicnew
Where x = 0.9 and y is given as a function of LV γ/ as
L
V
γ
0.50 0.55 0.60 0.65 0.70 0.75 0.80
γ 0.54 0.55 0.57 0.58 0.60 0.62 0.64
Where
knotsVtonsandwhere
V
EHP
:,:1.42733/2
∆
∆
=Θ ×
(ii) Length correction as suggested by wand G (RINA 1977)
( ) 4
1221 104@@ −
−=− xLLLL
This correction is approximate where .: ftL
(e) Estimation of EHP from series Data wetted surface Area S in 2
m is given as
mLmLS ==∇∆= ,,.
2 3
η
π
=η Wetted surface efficiency (see diagram of Telfer, Nec, Vol. 79, 1962-63).
The non-dimensional resistance coefficients are given as
== 2
2/1 VS
R
C R
R
ρ
This can be estimated from services data with corrections.
2
2/1 VS
R
C F
F
ρ
=
From ITTC,
( )2
10 2log
075.0
−
=
n
F
R
C
Where
v
VL
NosynoldRn =.'Re:

andViscocityoftcoefficienKinematicv=
waterfreshformWFforandwaterseaform sec/10139.1.,.sec/10188.1 2626 −−
××=
( ) 3
10004.08.0
0004.0
−
×−=
=
=
lwA
A
LCor
generalin
AllowanceRoughnessC
where minisL lw
2
2/1 VS
R
CCCC T
ARFT
ρ
=++=
Where .tanceresishullbaretheisRT
To get total resistance, Appendage resistance must be added to this:
Twin Screw Bossings 8 to 10%
A bracket 5%
Twin Rudder 3%
Bow Thruster 2 to 5%
Ice Knife 0.5%
If resistance is in Newtons and V is in m/sec,
( ) .25.11.1 KWtoEHPEPH Lrialservice ×=
(f) :DatalstatisticafromEHP See Holtrop and Mannen, ISP 1981/1984 (given at the
end of these notes)
(g) Estimation of SHP or shaft horse power
QPC
EHP
SHP service
=
10000
0
LN
KQPC RH
γ
ηηη −==
Where RPMN =
minLL PB=

84.0=K For fixed pitch propellers
82.0= For controllable pitch propellers can be estimated more accurately
later
(h) sBHP
lossesonTransmissiSHPBHPs +=
Transmission loss can be taken as follows:
Aft Engine 1%
Engine Semi aft 2%
Gear losses 3 to 4%
(i) Selection of Engine Power:
The maximum continuous rating (MCR) of a diesel engine is the power the engine
can develop for long periods. By continuous running of engine at MCR may cause
excessive wear and tear. So Engine manufactures recommend the continuous service
rating (CSR) to be slightly less than MCR. Thus CSR of NCR (Normal Continuous
Rating)
( )95.085.0 toMCR×=
Thus engine selected must have MCR as
.95.0/85.0/sBHPMCR =
Thus
PEN trial PET service PES
(Naked hull HP) Allowance Allowance
QPC
0.85 to 0.95 Shafting
MCR sBHP SHP
(NCR) losses
Select Engine
9.0 Seakeeping Requirement
9.1 Bow Freeboard bowF

L
V
γ
0.60 0.70 0.80 0.90
L
Fbow
0.045 0.048 0.056 0.075
(b) Probability of Deckwetness P for various LFbow / values have been given in
Dynamics of Marine Vehicles, by R.Bhattacharya:
( )tfL 200 400 600 800
( )mL 61 122 183 244
LFbow / for
P = 0.1% 0.080 0.058 0.046 0.037
1% 0.056 0.046 0.036 0.026
10% 0.032 0.026 0.020 0.015
Estimate bowF check for deckwetness probability and see if it is acceptable. bowF
Should also be checked from load line requirement.
9.2
Early estimates of motions natural frequencies effective estimates can often be
made for the three natural frequencies in roll, heave, and pitch based only upon
the characteristics and parameters of the vessel. Their effectiveness usually
depends upon the hull form being close to the norm.
An approximate roll natural period can be derived using a simple one-degree of
freedom model yielding:
tMGkT /007.2 11=φ
Where 11k is the roll radius of gyration, which can be related to the ship beam
using:
KBk 50.011 = , With 82.076.0 ≤≤κ for merchant hulls and 00.169.0 ≤≤κ
generally.
Using B40.011 ≈κ . A more complex parametric model for estimating the roll
natural period that yields the alternative result for the parameter κ is

( ) ( ) ( )( ) ( ) )//2.20.12.01.12.0(724.0
2
BDTDCCCC BBBB +−−×+−+=κ
Roll is a lightly damped process so the natural period can be compared directly
with the domonant encounter period of the seaway to establish the risk of resonant
motions. The encounter period in long- crested oblique seas is given by:
( )( )we gVT θωωπ cos//2 2
−=
Where ω is the wave frequency, V is ship speed, and wθ is the wave angle relative
to the ship heading with
•
=0wθ following seas,
•
= 09wθ beam seas, and
•
= 018wθ
Head seas. For reference, the peak frequency of an ISSC spectrum is located at
1
185.4 −
T with 1T the characteristics period of the seaway. An approximate pitch
natural period can also be derived using a simple one- degree of freedom model
yielding:
LGMkT /007.2 22=θ
Where now 22k is the pitch radius of gyration, which can be related to the ship
length by noting that .26.024.0 22 LkL ≤≤
An alternative parametric model reported by Lamb can be used for comparison:
( ))/36.06.0(/776.1 1
TCTCT Bpw += −
θ
Pitch is a heavily-damped (non resonant) mode, but early design checks typically
try to avoid critical excitation by at least 10%
An approximate heave natural period can also be derived using a simple one
degree-of-freedom model. A resulting parametric model has been reported by
Lamb:
( ) )/2.13(007.2 pwBh CTBCTT ++=
Like pitch, heave is a heavily damped (non resonant) mode. Early design checks
typically try to avoid having ,φTTh = ,θTTh = ,2 θTTh = ,θφ TT = ,2 θφ TT = which
could lead to significant mode coupling. For many large ships, however, these
conditions often cannot be avoided.

9.3 Overall Seakeeping Ranking used Bales regression analysis to obtain a rank
estimator for vertical plane seakeeping performance of combatant monohulls.
This estimator Rˆ yields a ranking number between 1 (poor seakeeping) and 10
(superior seakeeping) and has the following form:
apvfpvapwfpw CCLCLTCCR 9.155.23/27.1/3781.101.4542.8ˆ −−+−++=
Here the waterplane coefficient and the vertical prismatic coefficient are
expressed separately for the forward (f) and the aft (a) portions of the hull. Since
the objective for superior seakeeping is high Rˆ , high pwC and low ,pvC
Corresponding to V-shaped hulls, can be seen to provide improved vertical
plane seakeeping. Note also that added waterplane forward is about 4.5 times as
effective as aft and lower vertical prismatic forward is about 1.5 times as effective
as aft in increasing Rˆ . Thus, V-shaped hull sections forward provide the best way
to achieve greater wave damping in heave and pitch and improve vertical plane
seakeeping.
10. Basic Ship Method
1. Choose basic ship such that ,/ LV γ ship type and are nearly same and
detailed information about the basic ship is available.
2. Choose BCTBL from empirical data and get ∆
Such that ( ) ( )newbasic wdwd ∆=∆ // .
Choose BCTBL ... etc as above to get new∆
= BCTBL .033.103.1 to×
3. Satisfy weight equation by extrapolating lightship from basic ship data.
4. For stability assume ( )newbasic DKGDKG /)/( = with on your deletion
5. Check capacity using basic ship method. Use inference equation wherever
necessary
10.1 Difference Equations

These equations are frequently used to alter main dimensions for desired small
changes in out put. For example
ρBCTBL ...=∆
Or, =∆log +Llog +Blog +Tlog ρloglog +BC
Assuming ρ to be constant and differentiating,
B
B
C
Cd
T
Td
B
Bd
L
Ldd
+++=
∆
∆
So if a change of ∆d is required in displacement, one or some of the parameters
BCorTBL ,,, can be altered so that above equation is satisfied. Similarly, to
improve the values of BM by dBM, one can write
TBMB /2
α
or TBkMB /2
×=
or TBkBM loglog2loglog −+=
Differentiating and assuming k constant
T
dT
B
dB
BM
dBM
−=2
11. Hull Vibration Calculation
11.1 For two node Vertical Vibration, hull frequency is
(cpm)
N = 





∆ 3
L
I
φγ [Schlick]
Where I : Midship m . i. in 22
ftin
∆ : tons, L : f t
φ = 156 , 850 for ships with fine lines
= 143, 500 for large passenger lines

= 127, 900 for cargo ships






∆
= 3
3
(cpm) L
BD
N βγ
B: breadth in ft and D : Depth upto strength dk in ft. This is refined to take into
account added mass and long s .s. decks as,
( ) 2
2/1
3
3
1
(cpm) )3/2.1
.
C
LTB
DB
CN E
+





∆+
= [ Todd]
Where DE : effective depth
DE : [ ] 3/1
1
3
1 / LLD∑
Where D1: Depth from keel to dk under consideration
L1 : Length of s.s. dk
C1 C2
Tankers 52000 28
Cargo Vessels 46750 25
Passenger Vessels
With s.s 44000 20
( )( )
2/1
3
12/1






++∆
Ι
=
SrTBL
N φ Burill
Where =φ 2,400,000, I : ft4
, others in British unit
rS : shear correction =
( ) ( ) ( )( )
( )1/3
2.1/6/9/35.3
2
23
+
+++
DBL
DBDBDBD

( )
[ ]Bunyanwhere
TBC
DT
L
K
N
B
E
n
2/1
16.3






+
=
K = 48,700 for tankers with long framing
34,000 for cargo ships
38,400 for cargo ships long framed
n= 1.23 for tankers
1.165 for cargo ships
All units are in British unit.
T1 : Mean draught for condition considered
T : Design Draught
N3V = 2. N2V
N4V = 3.N2V
11.2 Hull Vibration (Kumai)
Kumai’s formula for two nodded vertical vibration is (1968)
N2v = 3. 07 * 106 cpm
Li
v
3
∆
Ι
Then Iv = Moment of inertia (m4
)
=∆i ntdisplaceme
T
B
m
=∆





+
3
1
2.1
including virtual added mass of water (tons)
L = length between perpendicular (m)
B= Breadth amidship (m)
Tm == mean draught (m)
The higher noded vibration can be estimated from the following formula by Johannessen
and skaar (1980)
( )∝
−≈ 12 nNN vnv
Then 845.0=∝ general cargo ships

1.0 bulk carriers
1.2 Tankers
N2V is the two noded vertical natural frequency. n should not exceed 5 or 6 in
order to remain within range validity for the above equation.
11.3 Horizontal Vibration
For 2 node horizontal vibration, hull frequency is
cpm
L
BD
N HH
2/1
3
3
2
.
.






∆
= β [Brown]
Where =Hβ 42000, other quantities in British units.
vH NN 22 5.1=
HH NN 23 .2=
HH NN 24 3=
11.4 Torsional Vibration
For Torsional vibration, hull frequency is
2/1
22
5
.
103 





∆+
×=
LDB
I
CN
p
T
cpm [Horn]
TNnodeoneforC −= 1,58.1
TNnodetwofor −= 2,00.3
TNnodethreefor −= 3,07.4
( )42
/4 ft
T
ds
AI p Σ= (This formulae is exact for hollow circular cylinder)
=A Area enclosed by section in 2
ft
=gd Element length along enclosing shell and deck )( ft
=t Corresponding thickness in )( ft
.:,:,, tonsftDBL ∆

11.5 Resonance
Propeller Blade Frequency = No. of blades × shaft frequency.
Engine RPM is to be so chosen that hull vibration frequency and shaft and
propeller frequency do not coincide to cause resonance.
References
1. ‘ShipDesign and Construction’ edited by Thomas Lab SNAME, 2003.
2. ‘Engineering Economics in ship Design, I.L Buxton, BSRA.
3. D. G. M. Waston and A.W. Gilfillan, some ship Design Methods’ RINA, 1977.
4. P. N. Mishra, IINA, 1977.
5. ‘Elements of Naval Architecture’ R.Munro- Smith
6. ‘Merchant Ship Design’, R. Munro-Smith
7. A. Ayre, NECIES, VOl. 64.
8. R. L. Townsin, The Naval Architect (RINA), 1979.
9. ‘Applied Naval Architecture’, R. Munro-Smith
10. M. C. Eames and T. C. Drummond, ‘Concept Exploration- An approach to Small
Warship Design’, RINA, 1977.
11. Ship Design for Efficiency and Economy- H Schneekluth, 1987, Butterworth.
12. Ship Hull Vibration F.H. Todd (1961)
13. J. Holtrop- A statistical Re- analysis of Resistance and Propulsion Data ISP 1984.
14. American Bureau of ships- Classification Rules
15. Indian Register of ships- Classification Rules
16. Ship Resistance- H. E. Goldhommce & Sr. Aa Harvald Report 1974.
17. ILLC Rules 1966.

Resistance Estimation Statistical Method (HOLTROP) 1984
RTotal = ( ) ATRBWAppF RRRRRKR ++++++ 11
Where:
=FR Frictional resistance according to ITTC – 1957 formula
=1K Form factor of bare hull
=WR Wave – making resistance
=BR Additional pressure resistance of bulbous bow near the water surface
=TRR Additional pressure resistance due to transom immersion
=AR Model –ship correlation resistance
=AppR Appendage resistance
The viscous resistance is calculated from:
SKCvR Fv )1(
2
1
10
2
+= ρ …………….(i)
Where
=0FC Friction coefficient according to the ITTC – 1957 frictional
=
( )2
10 2log
075.0
−nR
11 K+ was derived statistically as
11 K+ = ( ) ( ) ( ) ( ) 6042.0
3649.0312.04611.00681.1
1.//././4871.093.0
−
−





∇+ PR CLLLLTLBc
C is a coefficient accounting for the specific shape of the after body and is given by
C = 1+0.011 SternC
SternC = -25 for prom with gondola
= -10 for v-shaped sections
= 0 for normal section shape
= +10 for U-shaped section with hones stern

RL is the length of run – can be estimated as
=LLR / ( )14/06.01 −+− ppp CLCBCC
S is the wetted surface area and can be estimated from the following statistically derived
formula:
( ) ( ) BrBwpMBM CACBCCCBTLS /38.23696.0003467.02862.04425.04530.02 5.0
++−−++=
Where
=T Average moulded draught in m
=L Waterline length in m
=B Moulded breadth in m
=LCB LCB ford’s ( )+ or aft ( )− of midship as a percentage of L
=rBA Cross sectional area of the bulb in the vertical plane intersecting the stern contour
at the water surface.
All coefficient are based on length on waterline.
The resistance of appendages was also analysed and the results presented in the form of
an effective form factor, including the effect of appendages.
( )[ ]
totS
appS
KKKK 121 1111 +−+++=+
Where
=2K Effective form factor of appendages
=appS Total wetted surface of appendages
=totS Total wetted surface of bare hull and appendages
The effective factor is used in conjunction with a modified form of equation (i)
( )KSCVR totFov += 12
2
1
ρ
The effective value of 2K when more than one appendage is to be accounted for can be
determined as follows
( )
( )
∑
∑ +
=+
i
ii
effective
S
kS
k
2
2
1
1
In which iS and ( )i
k21+ are the wetted area and appendage factor for the i th appendage

TABLE: EFFECTIVE FORM FACTOR VALUES 2K FOR DIFFERENT APPENDAGES
Type of appendage ( )21ofvalue k+
Rudder of single screw ship 1.3 to 1.5
Spade type rudder of twin screw ship 2.8
Skeg-rudder of twin screw ships 1.5 to 2.0
Shaft Brackets 3.0
Bossings 2.0
Bilge keels 1.4
Stabilizer fins 2.8
Shafts 2.0
Sonar dome 2.7
For wave-making resistance the following equation of Havelock (1913)
Was simplified as follows:
( )2
2321 cos1 −
+= n
Fmw
Fmeccc
W
R d
n
λ
In this equation λ,,, 321 CCC and m are coefficients which depend on the hull form. Lλ is
the wave making length. The interaction between the transverse waves, accounted for by
the cosine term, results in the typical humps and hollows in the resistance curves.
For low-speed range 4.0≤nF the following coefficients were derived
( ) ( ) 3757.10796.1
7861.3
41 902223105
−
−= Ei
B
TCC
with:
( )







≥−=
≤≤=
≤=
25.00625.05.0
25.011.0
11.02296.0
4
4
3333.0
4
L
Bfor
B
LC
L
Bfor
L
BC
L
Bfor
L
BC
d = -0.9
( ) ( ) 5
3
1
1 7932.47525.101404.0 C
L
B
LT
Lm −−




∇−=
with:




≥−=
≤+−=
8.07067.07301.1
8.09844.68673.130798.8
5
32
5
pp
pppp
CforCC
CforCCCC
24.3
034.0
62 4.0
−
−
= nF
eCm

with:







≥
∇
→=
≤
∇
≤





−
∇
+−=
≤
∇
→−=
17270.0
172751236.2/0.869385.1
51269385.1
3
6
3
3
16
3
6
LforC
LforLC
LforC
( ) 1203.0446.1 ≤−=
B
Lfor
B
LCpλ
1236.0446.1 ≥−=
B
LforCpλ
where
Ei = half angle of entrance of the load waterline in degrees
( ) ( ) 3
32
8.6
1551.032.23425.16267.125 




 −
+++−=
T
TT
LCBCC
L
Bi
fa
ppE
where Ta = moulded draught at A.P
Tf = moulded draught at F.P
The value C2 accounts for the effect of the bulb.
C2 = 1.0 if no bulb’s fitted, otherwise
( )iBT
A
eC
B
BBT
+
= −
ν
ν89.1
2
where
Bν is the effective bulb radius, equivalent to
5.0
56.0 BTB A=ν
i represents the effect of submergence of the bulb as determine by
BBf hTi ν4464.0−−=
where
Tf = moulded draught at FP
hB = height of the centroid of the area ABT above the base line
( )MT BTCAC /8.013 −=
3C accounts for the influence of transom stern on the wave resistance
AT is the immersed area of the transom at zero speed.
For high speed range 55.0≥nF , Coefficients 1C and 1m are modified as follows
( ) ( ) 4069.10098.23.346.3.1
1 2/3.6919 −∇= −
B
LLCC M
( ) ( ) 6054.03269.0
1 2035.7
B
T
L
Bm −=

For intermediate speed range ( )55.04.0 ≤≤ nF the following interpolation is used
( ){ }







 −−
+=
5.1
4.0101 0455.0
04
FnFn
Fn
WWn
W
W
RRF
R
WW
R
The formula derived for the model-ship correlation allowance CA is
( )
( ) ( ) ( )
04.0/
/04.05.7/003.000205.0100006.0
04.0/00205.0100006.0
2
45.016.0
16.0
≥



−+−+=
≥−+=
−
−
WLF
WLFBWLWLA
WLFWLA
LTfor
LTCCLLC
LTforLC
where C2 is the coefficient adopted to account for the influence of the bulb.
Total resistance
( )[ ] W
W
R
CkCSR W
AFtotT .1
2
1 2
+++= νρ

Preliminary ship-design

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