International Journal of Engineering Research and Development (IJERD)

International Journal of Engineering Research and Development
e-ISSN: 2278-067X, p-ISSN: 2278-800X, www.ijerd.com
Volume 8, Issue 3 (August 2013), PP. 31-41
31
Design of Catamaran Ship Main Deck and Bulkhead to
Withstand the Crane Load
Dasari. V. G. Srinivas1
, Ch. Srinivas2
, R. Lalitha Narayana3
1
M.Tech Student, 2
Associate professor, 3
Head of the Department
1,2,3
Department of Mechanical Engineering A.S.R. College of Engineering Tanuku
Abstract:- Catamaran is a dual hull ship which has many advantages then the mono hull ship. Some of the
advantages are excellent stability, Cruise in shallow water, large wide deck areas, large load carrying capacity,
faster and Motion comfort etc. In this paper work, design of main or strength deck and Bulkhead structural
member calculations for Catamaran ship used for transport for the crane (Mantis® 10010mx 46 ton tele-boom
crawler crane) to its place of work. Ship’s main deck or Strength deck hull structural scantlings or calculations
play a very vital role in carrying the deck loads such as crane load safely against the external pressures which
are acting on the deck. This can done by designing the suitable deck and hull plate thickness, and it’s
strengthening stiffening. The design of main deck involves determination of scantlings of deck plate, deck
plate stiffeners, girders, pillars, Bulkhead and its stiffeners against the wheel load. Scantlings of deck and
Bulkhead plates, stiffeners and girders to meet the local strength requirements are to be determined in
accordance with the general principles of the rules. Scantlings of hull members should contribute the
longitudinal strength of the ship and to be subjected to compressive stresses. The design calculations are
carried out according to Indian Register of shipping (IRS) Rules and Regulations, Construction &
Classification of steel ships July 2013. This design process gives the effective & efficient solutions to the new
generation ships.
Keywords: Catamaran, Strength or Main deck, Bulkhead, Hull design, Structural members, Design loads, IRS
rules 2013.
I. INTRODUCTION
Catamaran is a dual hull ship which has many advantages then the mono hull ship. Some of the
advantages are excellent stability, Cruise in shallow water, large wide deck areas, large load carrying capacity,
faster and Motion comfort etc.
In this project work, design of main deck for Catamaran ship used for transport for the crane
(Mantis® 10010mx 46 ton tele-boom crawler crane) to its place of work in overseas. Decks contribute to
structural strength and preserve watertight integrity. It’s stiffened by the beams and longitudinal girders. The
beams and girders are generally rolled steel tee bars, toe welded, the beams being slotted to enable the girders
to be worked continuously. Comparing all decks the uppermost continuous deck, being farthest from the
neutral axis of the ship's section and therefore the most highly stressed, is worked as a strength deck and the
scantlings suitably increased. Only really essential openings are permitted to be cut in this deck, such openings
have to be carefully disposed to avoid lines of weakness and the corners of each opening are radiused to reduce
the concentration of stress which occurs there.
In this paper, Ship designing Rules like IRS (Indian Register of shipping July 2013) rules are used for
calculating the scantlings of structural members of main deck and Bulkhead, where it can with stand crane
loads acting upon the ship. The ship building materials which are approved by the classification society and
amount of corrosion additions are added to actual design calculations are considered and demonstrate the
model main deck calculations, Model outputs and Cad drawings.
Materials Of Construction
The Rules relate, in general, to the construction of steel ships.
STEEL GRADES
Ordinary hull structural steel is a hull structural steel with a minimum yield stress of 235 [N/mm2]
and a tensile strength generally in the range of 400-490 [N/mm2]. For ordinary hull structural steel, the
material factor `k' is to be taken as 1.0 ---------- (5.1.a)

Design Of Catamaran Ship Main Deck And Bulkhead To Withstand the Crane Load
32
Steels having a yield stress of 265 [N/mm2] and higher, are regarded as higher tensile steels. Where higher
tensile steel is used, the hull girder section modulus and the local scantlings may be reduced in accordance
with the relevant requirement of the Rules. For this purpose, a material factor 'k', is to be taken as follows:
k = 0.78 for steel with a minimum yield stress of 315 [N/mm2]
k = 0.72 for steel with minimum yield stress of 355 [N/mm2]
k = 0.68 for steel with minimum yield stress of 390 [N/mm2].
1.1 CORROSION ADDITIONS:
The thickness of plates, stiffeners and girders in tanks for water ballast and/or cargo oil and in holds of dry
bulk cargo carriers is to be increased by a corrosion addition 'tc'
The required corrosion addition 'Zc' to the section modulus of stiffeners and girders due to the thickness
addition 'tc' mentioned above may be approximated as:
Where
Zc = corrosion addition [cm3]
tC =thickness addition
hw = height of the web
bf =breadth of the flange
1.2 PRINCIPAL PARTICULARS CATAMARAN SHIP:
 Length Over All (L.O.A) 19.5m
 Length between Perpendiculars (L) 18.5m
 Breadth 9.00m
 Depth 2.0m
 Draft 1.0m
II. FRAME SPACING
The normal frame spacing between aft peak and 0.2L from F.P. may be taken as:
450 + 2L [mm] for transverse framing,
550 + 2L [mm] for longitudinal framing
However, it is generally not to exceed 1000 [mm].
Elsewhere, the frame spacing is generally not to exceed the following:
- In peaks and cruiser sterns:
600 [mm] or as in (1), whichever is lesser.
- Between collision bulkhead and 0.2L from F.P.:
700 [mm] or as in (1), whichever is lesser.
Where the actual frame spacing is higher than that mentioned above, the minimum thicknesses of various
structural members as given in the Rules may require to be increased.
Frame Spacing:
Frame spacing (s) = 550 + 2L [mm] for longitudinal framing.
= 550 + (2x18.5)
= 587mm
Let us consider Frame spacing is (s) = 500 mm
III. DECKS FOR WHEEL LOADING
Where it is proposed either to stow wheeled vehicles on the deck or to use wheeled vehicles for cargo
handling, the requirements of this section are to be complied with in addition to those given in the preceding
sections.
The requirements given below are based on the assumption that the considered element (Deck plating
and/or stiffener) is subjected to one load area only, and that the element is continuous over several evenly
spaced supports. The requirements for other loads and/or boundary conditions will be specially considered.
A "load area" is the tyre print area of individual wheels; for closely spaced wheels it may be taken as the
enveloped area of the wheel group. These details are to include the proposed arrangement and dimensions of
tyre prints, axle and wheel spacings, maximum axle load and tyre pressure.

33
Wheel load on deck
The pressure 'p' from the wheels on deck is to be taken as:
where,
W = maximum axle load, [t]. For fork lift trucks, the total weight is to be taken as the axle load.
n = number of "load areas" per axle
a = extent [mm], of the load area parallel to the stiffener [Fig 3.0]
b = extent [mm], of the load area perpendicular to the stiffener [Fig 3.0]
Fig. 3.0
av = vertical acceleration [m/s2], as follows:
for stowed vehicles, in sea going condition
for cargo handling vehicles in harbour condition
kv = 1.3 aft of A.P.
= 0.7 between 0.3L and 0.6L from A.P.
= 1.5 forward of F.P.
ao = common acceleration parameter
Cv =L/50, for L 100[m]
= 0.2 for L ≥ 100 [m]
3.1 Deck Pressure for Wheel Loading
P =
Pressure = W / n a b (9.81+0.5 av) 103
0.065
N/mm2
W = Maximum axial load (Crane load) 46.00
T
n = Number of "load areas" per axle 2.00
a = Extent of the load area parallel to the stiffener 800
mm
b = Extent of the load area perpendicular to the stiffener 5100
mm
av = Vertical acceleration

34
9.81 kv ao /Cb (For stowed vehicle in sea going
condition)
3.58
6/W--------(For cargo handing vehicles in harbour
condition) 1.90
L = Length 18.50 m
Cw = 0.0856 x L 1.58
Cb = Block coefficient 0.80
kv = 0.70
ao =
common acceleration parameter
3Cw / L + Cv V / L 0.42 N/mm2
Cv = L/50 0.09
V = Speed 8
3.2 Deck plating
The thickness’t’ of deck plating subjected to wheel loadings is not to be less than;t [mm]
Where,
fa = (1.1 - 0.25 s/l) for s ≤ l,
However need not be taken as greater than 1.0
a,b,s,l = deck panel dimensions [mm]
c1 = 0.137 in general for seagoing conditions
= 0.127 in general for harbour conditions
= As per Table 4.7.a for upper deck within 0.4L amidships.
For upper deck plating between 0.4L amidships and 0.1L from ends, c1 is to be varied linearly. However, need
not be taken as greater than 1.0
-
DECK PLATING THICKNESS:
t =
Thickness of deck plate =
(c1 fa  (c2 b s p k / m)) + tc 6.03 mm
p = Pressure 0.065 N/mm2
a = Extent of the load area parallel to the stiffener 1000 mm
Table 3.2.a

35
b =
Extent of the load area perpendicular to the
stiffener 500 mm
s = Spacing of the stiffeners 500 mm
l = Span of the stiffener 1000 mm
fa = (1.1-0.25.s/l) 0.975
Let 'fa' be 1
c1 = For Sea going condition 0.137
General habour condition 0.145
c2 = 1.3 - (4.2/(a/s+1.8)2
) 1.009
m = 38/((b/s)2
-4.7 (b/s)+6.5 13.57
k = Material Factor 1
tc = Corrosion addition to thickness 1.5 mm
3.3 DECK STIFFENERS OR BEAMS
The section modulus 'Z' of deck beams and longitudinals subjected to wheel loadings is not to be less than:
C3 = (1.15 0.25 b/s) for b ≤ s,
however need not be taken as greater than 1.0
r = 29 for continuous stiffeners supported at girders
= 38 when the continuous stiffeners can be considered as rigidly supported at girders against rotation.
σ = 160/k [N/mm2] in general, for seagoing conditions
= 180/k [N/mm2] in general, for harbour conditions
= As per Table 4.8.a for deck longitudinals within 0.4L amidships, but not exceeding the above general values.
For deck longitudinals between 0.4L amidships and 0.1L from ends is to be varied linearly.
Table : 3.3
DECK BEAMS OR STIFFENERS:
Corrosion addition (Zc) for Stiffeners (L 60x60x6)
Zc= Section Modulus = tc.hw (bf+0.3.hw)/1000
9.3
6 cm3
tc= Corrosion addition = tn x 0.2 1.2 mm
From [table 6.a] Let us take 'tc' 2 mm
tn= Net thickness of member 6 mm
hw= Height of the web 60 mm
bf= Breath of the flage 60 mm

36
Z = Section Modulus = (((c3 a b l p) /( m σ)) 10-3
) +Zc
17.75+9.36=
27.11 cm3
c3 = (1.15-0.25 b/s) 0.9
m = r/{(a/l)2
-4.7 (a/l) + 6.5} 10.35
r =
For continuous stiffeners supported at girders
29
When the continuous stiffeners can be considered
as rigidly supported at girders against rotation 38
σ = For seagoing conditions 160 N/mm2
For harbour conditions 180 N/mm2
p = Pressure 0.065 N/mm2
a = Extent of the load area parallel to the stiffener--- 1000 mm
b =
Extent of the load area perpendicular to the
stiffener 500 mm
s = Spacing of the stiffeners 500 mm
l = Span of the stiffener 1000 mm
3.4 DECK GIRDERS
Deck girders and transverses are to be arranged in line with vertical members of scantlings sufficient
to provide adequate support.
The scantlings of simple girders and transverses are to be calculated by following formula. The
section modulus 'Z' of deck girders is not to be less than:
Where,
p = applicable design pressure [N/mm2]
m = 12 for continuous longitudinal girders with end ---- (4.9.b)
m = 10 for other girders with end attachments ----------- (4.9.c)
σ = (190-135fD.fz)/k
max. σ = 160/k [N/mm2] for continuous longitudinal girders within 0.4L amidships.
σ = 160/k [N/mm2] for longitudinal girders within 0.1L from ends and for transverse girders in general,
Elsewhere, `σ' may be obtained by linear interpolation.
DECK LONGITUDINAL GIRDERS:
Corrosion addition (Zc) for Long. Girders (Web 180x6+80x6
FP)
Zc= Section Modulus = tc.hw (bf+0.3.hw)/1000
48.2
4 cm3
From [table 6.a Let us take 'tc' 2 mm
bf= Breath of the flage 80 mm
Z =
Section Modulus = ((b p S2
106
/ (m
σ))+Zc
136.2+48.24
=
184.44 cm3
b = Spacing of girders 1 m
p = Pressure 0.065
N/mm
2
S = Span of girder 2 m

37
m =
For continuous longitudinal girders
12
For other girders 10
σ = Allowable Bending stress 160
N/mm
2
DECK TRANSVERSE WEBS:
Corrosion addition (Zc) for Trans. Girders (Web 180x6+50x8 FP)
Zc= Section Modulus = tc.hw (bf+0.3.hw)/1000 37.44 cm3
[From table 6.a] Let us take 'tc' 2 mm
bf= Breadth of the flage 50 mm
Z = Section Modulus = (b p S2
106
/ m σ) + Zc
81.73+37.44=
119.17 cm3
b = Spacing of girder 2 m
p = Pressure 0.065
N/mm
2
S = Span of girder 1 m
m = For continuous longitudinal girders 12
For other girders
10
σ = Allowable Bending stress 160
N/mm
2
3.5 DECK PILLARS:
Pillars are to be fitted in the same vertical line wherever possible, and arrangements are to be made to
effectively distribute the load at the heads and heels. Where pillars support eccentric loads, they are to be
strengthened for the additional bending moments imposed upon them. Doubling or insert plates are generally
to be fitted at the head and heel of hollow pillars. The pillars are to have a bearing fit and are to be attached to
the head and heel plates by continuous welding.
Sectional area of the pillar 'A' is not to be less than
A = 70.AL.p [cm2]
Where,
p = design pressure as given in Sec.3, causing the tensile stress in pillar
AL = load area of deck [m2], being supported by the pillar.
DECK SUPPORTED PILLARS:
Deck Pillar
A = Sectional Area = 70 AL p 9.1539971 cm2
AL = Deck Area Supported by Pillar 2 m2
p = Design pressure 0.0653857 N/mm2
3.6 Pressure for watertight bulkhead:
The design pressure 'p', for ordinary watertight bulkheads is given by:
p = 0.01 h [N/mm2]
where,
h = the vertical distance [m] from the center of loading to the freeboard deck.
PRESSURE FOR WATERTIGHT BULKHEAD:

38
P= applicable design pressure 0.01*h 0.010
N/mm
2
h=
height from load point to
freeboard deck 1 m
3.7 Transverse Bulkhead plating:
The thickness 't' of the bulkhead plating is not to be less than the minimum thickness given in 3.8 nor less than
where, p = applicable design pressure as given in 3.6.
σ = 160/k for transverse tank bulkheads and collision bulkhead;
= 220/k for ordinary transverse watertight bulkheads.
= 190/k for transverse dry bulk cargo bulkheads
BULKHEAD PLATING THICKNESS:
t= Thickness of Bulkhead
{(s p) / (2  σ ))
}+ tc 1.98 mm
s= stiffener spacing 500 mm
σ =
allowable bending
stress 160 N/mm2
K= Material factor 1
3.8 Minimum bulkhead thickness:
The minimum thickness requirement of the bulkhead plating is given by
t = (5.0 + c*L) k + tc [mm]
where,
c = 0.02 for longitudinal bulkheads and bulkheads in cargo tank area and in peak tanks
= 0.01 for other bulkheads.
MINIMUM BULKHEAD TICKNESS:
t= Thickness of Bulkhead ((5+c*L) k)+tc 5.87 mm
tc=
Corrosional addition of plate
thickness 0.5 mm
L= Length 18.5 m
k= Material factor 1 mm
c= 0.02
3.9 Vertical and transverse stiffeners on tank bulkheads, collision bulkheads, dry bulk cargo bulkheads
and wash bulkheads:
The section modulus of bulkhead stiffeners is not to be less than:
where,
p = applicable design pressure given in 3.6
m = 10 for transverse stiffeners and vertical stiffeners which may be considered fixed at both ends
= 7.5 for vertical stiffeners simply supported at one or both ends
BULKHEAD VERTICAL STIFFENERS:
Z= section modulus
(spl2
* 103
/m σ)
+Zc 16.4325 cm3
zc=
corrosion addition to
section modulus
tc*hw(bf + 0.3
hw)/1000 3.9325 cm3
s= stiffener spacing 500 mm
l= span of stiffener 2 m

39
P=
applicable design
pressure 0.010
N/mm
2
hw= height of web 55 mm
bf= width of flange 55 mm
tc=
Corrosional addition of
plate thickness 1 mm
m=
for trans. & vertical
stiffeners 10
MODEL OUTPUTS AND CAD DRAWINGS
IV. DECK PLATE THICKNESS
S.No. Description Required Thk.(mm)
Provided
Thk.(mm)
1 Deck plate 5.53 mm thk plate 6mm thk. Plate
4.1 Deck Beams or Stiffeners and Girders
S.No. Description
Required
Section
Modulus
(cm3)
Provided
member
Section
Modulus(cm3)
Size of the member
1
Deck Beams or
Stiffeners
27.11 29.23 L-60x60x6
2
Deck Longitudinal
Girders
184.44 184.83 Web180x8+80x8FP
3
Deck Transverse
Girders
119.17 127.74 Web180x6+50x8 FP
4.2 Deck Supported Pillars:
4.3 Bulkhead plate thickness:
S.No. Description Required Thk.(mm) Provided Thk.(mm)
1 Bulkhead plate 5.87 mm thk. plate 6mm thk. Plate
4.4 Bulkhead vertical Stiffeners:
S.No. Description
Required
Section
Modulus
(cm3)
Provided
member
Section
Modulus(cm3)
Size of the member
1
Bulkhead vertical
Stiffeners
16.43 24.47 L-55x55x6
S.No. Description
Required C/S
Area (cm2
)
Provided Pipe size &
C/S Area (cm2
)
1
Deck Supported
Pillars
9.1539
Pipe 50.NB SCH.80, (O.D.
60.5, 5.5 THK)
C/S area – 9.5 (cm2
)

40

41
REFERENCES
[1]. Materials of Construction - IRS Rules (2013) Part 3, Chapter2, Section 2
[2]. Corrosion Additions - IRS Rules (2008) Part 3, Chapter3, Section 2.1
[3]. Principal Particulars of the Ship - IRS Rules (2008) Part 3, Chapter1, Section 2.1
[4]. Frame spacing- IRS Rules (2013), Part 3, Chapter 3, Section 1.3
[5]. Wheel Load on deck -IRS Rules (2013), Part 3, Chapter 9, Section 6
[6]. Deck; plating - IRS Rules (2013), Part 3, Chapter 9, Section 6.3
[7]. Deck stiffeners- IRS Rules (2013), Part 3, Chapter 9, Section 6.4
[8]. Deck Girders - IRS Rules (2008), Part 3, Chapter 9, Section 5.1
[9]. Deck Pillars - IRS Rules (2013), Part 3, Chapter 9, Section 5.3
[10]. Pressure for watertight bulkhead - IRS Rules (2013), Part 3, Chapter 10, Section 4.1
[11]. Transverse Bulkhead plating - IRS Rules (2013), Part 3, Chapter 10, Section 5.1
[12]. Minimum Bulkhead thickness - IRS Rules (2013), Part 3, Chapter 10, Section 5.12
[13]. Vertical and transverse stiffeners on tank bulkheads, collision bulkheads, dry bulk cargo bulkheads
and wash bulkheads - IRS Rules (2013), Part 3, Chapter 10, Section 5.3
[14]. Deck Beams or Stiffeners and Girders - Section Modulus with Attached plating of 610mm of standard
DIN Sections (Bureau Veritas, 2007)
[15]. Deck Supported Pillars - Dimension of Ferrous pipes; KSD 3507 (JIS G 3452), KSD 3562 (JIS G
454), KSD 3564 (JIS G 3455), KSD 3570 (JIS G 3456), BS 3601, BS 3602.

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