An Offshore supply vessel is a multi-task vessel and has to be designed for many different purposes. This is contrary to most other ships used worldwide. In general, the geographical location where the offshore activity takes place is an important indicator of the choice of supply vessel. Factors like weather conditions, the amount of equipment needed and the distance from the shore are important for what properties the vessel should have. The deep-water oilfield market is becoming more important as the conventional oilfield market in shallow water cannot meet the energy requirements from the consuming market. The Offshore Supply Vessels (hereafter it is called OSVs) market is becoming booming and the demand for OSVs has never reached the extent like today in previous periods. In this project an offshore supply vessel will be designed according to ABS Rules.

1. Offshore Support Vessels Design
By:
Ahmed Taha Abd El-Mawla

2. Contents
• Introduction
• Design of the vessel
• Resistance of the vessel
• Construction of the vessel
• Weight of the vessel
• Intact Stability

3. Introduction
• The origin of offshore support vessels may be traced to the Gulf of
Mexico.
where oil exploration first moved offshore in the 1950s.
• Surplus World War II vessels and wooden fishing boats were used to
supply offshore rigs

4. Design and operating capabilities
• Large and open aft deck.
• Highly maneuverable, particularly at low speed.
• Storage for offshore exploration and production activities:
such as bulk mud and cement, potable water
• Wheel house all - round visibility (have forward & aft control)
• High engine power for towing operations.
• Some OSVs are equipped with big fire pump with monitors for
external firefighting system.
• Dynamic Positioning (DP) system is very important for all types of
OSVs.

5. Types of Offshore Support Vessel
• Anchor Handling Towing Supply vessels (AHTS)
• Diving Support Vessels (DSV)
• Platform Supply Vessels (PSV)
• Cable & Pipe Laying Vessels
• Standby and Rescue Vessels
• Multi-Purpose Service Vessel (MPSV)

6. Features of offshore supply vessel
Work deck
Anchor roller
Steering gear
Ducted propeller
Stern TubeTransverse Thruster
Tanks For dry bulk
Deck cranes
Propeller shaftGear box
Maine engine
Life raft
MOB-boat with crane
Storage reel for steel
wires for anchor
BridgeFirefighting monitor
Switchboard

7. Design of vessel
• The design of a ship is an iterative process, in which early estimates
are made.
• Then repeatedly corrected.
• Design and Construction – IMO A.469 (XII)
• Design spiral• Main Particulars
Length overall = 20 m
Length B.P. = 19.3 m
Breath moulded = 6.66 m
Depth moulded = 3.3 m
Design draught = 2 m

8. Design of vessel
• Lines Plans
Before After

9. • Generation of the hull surface
Design of vessel

10. • General Arrangements
Design of vessel
Outboard Profile

11. Below Main Deck

13. • Preliminary hydrostatic calculations
Displacement 122.9 t
Volume (displaced) 119.895 m^3
Draft Amidships 2 m
Immersed depth 2.015 m
WL Length 19.392 m
Beam max extents on WL 6.144 m
Wetted Area 136.187 m^2
Max sect. area 7.821 m^2
Waterpl. Area 105.717 m^2
Prismatic coeff. (Cp) 0.79
Block coeff. (Cb) 0.499
Max Sect. area coeff.
(Cm) 0.636
Waterpl. area coeff.
(Cwp) 0.887
LCB length -0.158 (+ve fwd) m
LCF length -0.504 (+ve fwd) m
LCB % -0.813 (+ve fwd) % Lwl
LCF % -2.599 (+ve fwd) % Lwl
KB 1.333 m
BMt 2.41 m
BML 23.723 m
GMt corrected 3.743 m
GML 25.056 m
KMt 3.743 m
KML 25.056 m
Immersion (TPc) 1.084 tonne/cm
MTc 1.588 tonne.m
Design of vessel

14. Resistance of the vessel
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16 18 20 22 24
ResistanceKN
Speed Knots
Resistance Vs. Speed
Resistance
33.2 KN

15. 0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
0 2 4 6 8 10 12 14 16 18 20 22 24
PowerKW
Speed Knots
Speed Vs Power
Power
Resistance of the vessel 𝑸𝑷𝑪 = 𝟔𝟓 %
𝜼𝒕 = 𝟗𝟓 %
𝑩𝑯𝑷 = 𝟔𝟐 %
280 KW

16. Construction of vessel
• Calculation in detail according to the ABS rules:
Offshore Support Vessels 2016-Part 3 Hull Construction and Equipment
• CHAPTER 2: Hull Structures and Arrangements

17. Midship Section
6.667 m
0.5 m 1.65 m
Long.
L.75*50*6
C.G.
T.150*130*123.3 m
Deck 7.5mm PL.
Side 7.5mm PL.
Bottom 8mm PL.

18. 3D Model Representation

19. Weight of the vessel

20. Light weight Estimations
Steel weight 25 ton
Outfitting Weight 3 ton
Machinery Weight 5 ton
Total Light Weight 33 ton

21. Dead Weight
• Dead Weight = displacement – light weight
• 𝑾 𝒅 = 𝚫 − 𝑾𝒍 = 𝟏𝟐𝟐 − 𝟑𝟑 = 𝟗𝟎 𝒕𝒐𝒏
Freshwater 18.00 ton
Dry bulk cargo tanks (cement) 15.00 ton
Fuel oil 2.00 ton
Oil cargo 38.00 ton
Freshwater cargo 15.00 ton
Weight for persons 2.5 ton

22. Intact Stability
• Loading Conditions
1. Light weight Condition
2. Full load Condition
3. Vessel with 10% of consumables ,departure condition.
4. Vessel with 10% of consumables ,arrival condition.

23. Equilibrium
Draft Amidships m 1.960
Displacement t 118.3
Heel deg 0.0
Draft at FP m 2.012
Draft at AP m 1.909
Draft at LCF m 1.958
Trim (+ve by stern) m -0.103
WL Length m 19.399
Beam max 6.123
LCB. (+ve fwd) m -0.018
LCF. (+ve fwd) m -0.479
Full load Condition
KB m 1.309
KG fluid m 1.749
BMt m 2.447
BML m 24.444
GMt corrected m 2.006
GML m 24.003
KMt m 3.755
KML m 25.752
Immersion (TPc) tonne/cm 1.075
MTc tonne.m 1.464
Max deck inclination deg 0.3033
Trim angle (+ve by stern) deg -0.3033
𝑮𝑴 = 𝑲𝑴 − 𝑲𝑮 = 3.755-1.749 = 2.006

24. Light weight Condition 10% departure condition10% arrival condition
Draft Amidships m 1.018
Displacement t 33.00
Heel deg 0.0
Draft at FP m 0.657
Draft at AP m 1.379
Draft at LCF m 1.071
Trim (+ve by stern) m 0.722
KB m 0.769
KG fluid m 1.839
BMt m 3.481
BML m 54.615
GMt corrected m 2.410
GML m 53.544
KMt m 4.248
KML m 55.346
Trim angle (+ve by
stern) deg
2.1329
Draft Amidships m 1.898
Displacement t 112.6
Heel deg 0.0
Draft at FP m 1.775
Draft at AP m 2.021
Draft at LCF m 1.906
Trim (+ve by stern) m 0.245
KB m 1.279
KG fluid m 2.005
BMt m 2.500
BML m 24.951
GMt corrected m 1.775
GML m 24.226
KMt m 3.779
KML m 26.228
Trim angle (+ve by
stern) deg
0.7251
Draft Amidships m 1.402
Displacement t 62.82
Heel deg 0.0
Draft at FP m 1.311
Draft at AP m 1.494
Draft at LCF m 1.409
Trim (+ve by stern) m 0.183
KB m 0.973
KG fluid m 1.927
BMt m 3.064
BML m 37.415
GMt corrected m 2.110
GML m 36.461
KMt m 4.037
KML m 38.387
Trim angle (+ve by
stern) deg
0.5406

25. Large Angle Stability
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 10 20 30 40 50 60 70 80 90 100 110 120
GZm
Heel θ deg.
Full Load GZ - θ Curve
GZ
Initial GM
Max GZ
Range of Stability
θ 𝒇
Initial GM
Max GZ
θ

26. CRITERIA REQUIRED
Area between 0 and angle
of maximum GZ
3.1513 𝒎. 𝒅𝒆𝒈
Area from 30 to 40 deg. 1.7189 𝒎. 𝒅𝒆𝒈
Maximum GZ 0.200 𝒎
Angle of maximum GZ ≥15 𝒅𝒆𝒈
Initial GMt 0.150 𝒎
full load
Condition
23.7920
𝒎. 𝒅𝒆𝒈
9.9358 𝒎. 𝒅𝒆𝒈
1.005 𝒎
38.2 𝒅𝒆𝒈
2.006 𝒎
light weight
Condition
43.9612
𝒎. 𝒅𝒆𝒈
11.2493
𝒎. 𝒅𝒆𝒈
1.499 𝒎
51.8 𝒅𝒆𝒈
2.410 𝒎
10%
departure
condition
32.4616
𝒎. 𝒅𝒆𝒈
10.2960
𝒎. 𝒅𝒆𝒈
1.161 𝒎
46.4 𝒅𝒆𝒈
2.110 𝒎
10% arrival
condition
18.6107
𝒎. 𝒅𝒆𝒈
8.7455
𝒎. 𝒅𝒆𝒈
0.882 𝒎
35.5 𝒅𝒆𝒈
1.775 𝒎
IMO A.749 (18) ch4,5 Offshore supply vessels

27. 0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
KNm
Displacement (ton)
Cross Curves KN
0 deg KN m
10 deg KN m
20 deg KN m
30 deg KN m
40 deg KN m
50 deg KN m
60 deg KN m
70 deg KN m
KN Values Cross Curve of Stability

28. Upright Hydrostatics
0.0001 0.9182
3.887
9.267
17.51
29.17
44.42
61.99
81.22
101.6
122.8
0
20
40
60
80
100
120
140
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Displacement(ton)
Draft (m)
Draft Vs. Displacement
Displacement t

29. 0.045
10.123
22.036
36.005
52.632
71.788
90.55
101.766
112.464
121.427
130.268
0.04
9.205
20.035
32.794
48.108
65.547
81.586
89.82
97.129
101.504
105.652
0
20
40
60
80
100
120
140
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Area(m^2)
Draft (m)
Draft Vs. Area
Wetted Area
Waterpl. Area

30. 8.836
11.379
13.072
14.679
16.233
17.779
18.922 19.053 19.173 19.285
19.392
0.038 0.948 1.895
2.842
3.788
4.451 4.925
5.399 5.749
5.946 6.144
0
5
10
15
20
25
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
(m)
Draft (m)
WL Length
Beam max

31. 0.068
0.829
0.765
0.722
0.694
0.681 0.696
0.735
0.759 0.777 0.79
0.034
0.395
0.373
0.355 0.343 0.356 0.384
0.417 0.446
0.477
0.5
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
(m)
Draft (m)
Cp
Cb
Cwp
Cm

32. Thank You