Servicing the Arctic. Report 3: Design of an Arctic Offshore Supply Vessel (AMTSV)

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Servicing the Arctic

Report 3: Design of an Arctic Offshore Supply Vessel

Arctic Minor Team

Concept

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Servicing the Arctic

Report 3: Design of an Arctic Offshore Supply Vessel

Concept Design

R.W. Bos (4114620)

T.J. Huisman (4080777)

M.P.W. Obers (4113187)

T. Schaap (4089561)

M. van der Zalm (4095316)

Version: January 29, 2013

Faculty of Mechanical, Maritime and Materials Engineering (3mE) · Delft University of Technology

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Cover picture from: Free HD wallpapers (http://www.listofimages.com/kapitan-khlebnikov-icebreaker-ship-arctic-ice-winter-snow-other.html)

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Abstract

Background To design a ship its specific design requirements are to be known. These are, together with class notations, specified in previous reports and extended in this report. Since the requirements are formed iteratively, design freedom is possible. This is used to implement several innovations into the design which improve the performance of the vessel. The vessel is designed for worldwide operations to support offshore installations, in open waters and first year ice.

Results The vessel is built with regards to a good performance in open water and ice, safe transportation of cargo and safe working conditions for the crew. The hull of the ship is designed with three operational modes in mind. An open water bow for low resistance in open water, an ice bow to allow good performance in ice and both are designed to reduce slamming during dynamic positioning operations. Installation of two Azipod thrusters gives good maneuverability with little compromise on performance in ice or open water.

Four engines with three different sizes make sure the power supply meets the requirement, minimizing energy losses due to overcapacity. To meet strict environmental laws the ship is able to use LNG as fuel and therefore does not exhaust SO_x. Besides that fuel oil can be used in less strict areas. The hold is filled with tanks for dry bulk and liquid mud, meeting the average for this size of vessel. Winterization is achieved by the extended superstructure (ESS) which protects crew, cargo and even survivors from an oil rig catastrophe from the environment.

As the market changes, the demands for ships change. The modular container hold allows for extra tanks, pumps and engines to be placed, adapting the ship to owner needs. Even towing is possible, and might even be necessary when performing ice management.

There are however some design choices that require attention. The ESS, in combination with the LNG tanks, limits the line of sight from the bridge. Helicopter landing facilities should be provided, but are hard to achieve when the main deck is full of cargo. Because the ship has to sail through ice, a great power is installed, but not necessarily used.

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3-2 General arrangement . . . 53 3-2-1 Frame spacing . . . 53 3-2-2 Deck height . . . 53 3-2-3 Engine room . . . 53 3-2-4 Tank capacities . . . 53 3-2-5 Rescue equipment . . . 54 3-2-6 Retractable thruster . . . 55 3-2-7 Rail crane . . . 55 3-2-8 Accommodation . . . 55 3-3 Weights . . . 58 3-3-1 Hull weight . . . 58

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Contents v

3-3-2 Engine weight . . . 58

3-3-3 Cargo . . . 58

3-4 Freeboard and Trim . . . 60

3-4-1 Minimum bow height . . . 60

3-5 Stability . . . 61

3-6 Speed and Power . . . 62

3-6-1 Resistance . . . 62

3-6-2 Installed power . . . 62

3-7 Structure . . . 63

3-7-1 Hull section . . . 63

3-7-2 ESS model verification . . . 67

3-7-3 Longitudinal strength . . . 68

3-8 Propulsion Plant . . . 71

3-8-1 Propulsion Power . . . 71

3-8-2 Hotel requirements . . . 71

3-8-3 Engine requirement and selection . . . 71

3-8-4 Endurance . . . 71 3-9 Auxiliary systems . . . 73 3-10 Costs . . . 75 3-11 Evaluation . . . 76 3-11-1 Design process . . . 76 3-11-2 Owner requirements . . . 76 3-11-3 Class requirements . . . 77 3-11-4 Crew Conditions . . . 77 3-11-5 Environmental Awareness . . . 78 3-11-6 Design flaws . . . 78 3-11-7 Possible voyage . . . 79 A Class notations 81 A-1 Standby Vessel (S) . . . 81

A-2 Fire Fighter . . . 81

A-3 OILREC, section 10 . . . 82

A-4 HELDK . . . 82

A-5 Clean Design . . . 83

A-6 Human Factors . . . 83

B Innovation 85 B-1 General/ Transport . . . 85 B-2 Hullform . . . 86 B-3 Propulsion . . . 87 B-4 Layout . . . 87 B-5 Equipment . . . 88 B-6 Structure . . . 89 B-7 Safety . . . 89

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vi Contents

C SWOT Analysis 91

Propeller/Pod exchange . . . 92

Retractable thrusters . . . 93

Modular container hold . . . 94

Double draft . . . 95

Double acting hull . . . 96

Rescue slide . . . 97

Covered working deck . . . 98

Paint Arrangements . . . 99

LNG . . . 100

De-icing . . . 101

Active stability . . . 102

Use waste heat for heating . . . 103

Retractable nozzle . . . 104

Double acting winch . . . 105

D Comparison Ships 107 E General Arrangement Sketches 113 F Ship Data During Various Design Stages 125 G Hull Calculations for AMTSV Iteration 2 127 G-1 Freeboard calculation . . . 127

G-2 Resistance calculations . . . 127

G-3 Endurance . . . 130

G-4 Structure . . . 130

H Hull Calculations for AMTSV Iteration 3 133 H-1 Freeboard calculation . . . 133

H-2 Resistance calculations . . . 133

H-3 Endurance . . . 136

H-4 Structure . . . 136

I Engine output prediction for a vessel sailing astern through level ice based on Lindqvist 141 I-1 Introduction . . . 141

I-2 Lindqvist adapted for sailing astern through level ice . . . 141

I-3 Conclusion and outlook . . . 144

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Contents vii

J Extended Superstructure Calculations 147

J-1 Wind loads . . . 147

J-2 Accommodation floor on ESS . . . 148

J-3 Side walls of the ESS . . . 149

J-4 LNG support . . . 149

J-5 Results . . . 150

J-6 Verification . . . 150

K Lineplans and Stability Data 153 K-1 Second iteration . . . 153

K-2 Third iteration . . . 165

L General Arrangement 3 added details 177

M 3d renderings 179

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List of Figures

1 Design spiral [1] . . . 2

1-1 Route from Murmansk to a potential offshore platform. Adapted from [4] . . . . 4

1-2 SWOT model used for the analysis and appreciation of the ideas. Adapted from [5] 7 1-3 Length - Breadth . . . 14

1-4 Possible placement of winches in early design stage as orange circles in a side view. 16 1-5 First version of the general arrangement . . . 19

2-1 General Arrangement 2nd iteration 1/2 . . . 26

2-2 General Arrangement 2nd iteration 2/2 . . . 27

2-3 Division of weight areas of the AMTSV in early design stage. . . 29

2-4 General structure 2nd iteration . . . 38

2-5 Structure ice belt 2nd iteration . . . 41

2-6 Section arrangement to compare the weight. Frames with floors are marked green. 43 3-1 General Arrangement iteration 3 . . . 56

3-2 UPCR structure definition 3rd iteration . . . 65

3-3 Structure iteration 3 . . . 70

3-4 Class notations and the level of detail dealt with, omitted notations are black. The first column from the centre denotes notations that were chosen. The second column from the centre shows notations that have to be met for the notation in the corresponding row. . . 78

D-1 Deadweight - Length . . . 107

D-2 Displacement - Length . . . 108

D-3 Deadweight/displacement - Length . . . 108

D-4 Deck Area - Length . . . 109

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x List of Figures D-6 Power - Length . . . 110 D-7 Crew - Length . . . 110 D-8 PSV ratios 1 . . . 111 D-9 PSV ratios 2 . . . 111 D-10 Block coefficient . . . 112

E-1 General Arrangement Sketches based on the 1st iteration . . . 114

G-1 Input of the Holtrop and Mennen program of the TU Delft, 2nd iteration . . . . 128

H-1 Input of the Holtrop and Mennen program of the TU Delft, 3rd iteration . . . . 134

J-1 Windload, with qwind as blue gradient, the two sided cantilevered beam in gray and cross section besides it. . . 148

J-2 Loads acting on the wall of the ESS, with the wall in gray, the force and moment of the accommodation floor in green and the moment and force of the gantry crane in blue. . . 149

J-3 A deformed shape plot of the complete ESS model in Ansys. . . 152

K-1 Linesdrawing 2nd iteration profile view . . . 154

K-2 Linesdrawing 2nd iteration body plan . . . 155

K-3 Linesdrawing 2nd iteration plan view . . . 156

K-4 Equilibrium calculation at 80 % ballast 2nd iteration . . . 157

K-5 Equilibrium calculation at full cargo 2nd iteration . . . 161

K-6 Linesdrawing 3rd iteration profile view . . . 166

K-7 Linesdrawing 3rd iteration body plan . . . 167

K-8 Linesdrawing 3rd iteration plan view . . . 168

K-9 Equilibrium calculation at 80 % ballast 3rd iteration . . . 169

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List of Tables

1-1 Design requirements . . . 6

1-2 First estimations of dimensions for use in the general arrangement . . . 12

1-3 Main dimensions and tank capacities . . . 13

2-1 Second iteration results main dimensions . . . 22

2-2 Frame spacings . . . 23

2-3 Tank capacity . . . 24

2-4 Size and centre of gravity of weight blocks of the AMTSV in early design stage. . 29

2-5 Results engine calculations . . . 30

2-6 Total Lightweight . . . 30

2-7 Freeboard and trim iteration 2 . . . 31

2-8 Stability results 80% ballast and fully loaded cases . . . 32

2-9 Open water and ice resistance using Holtrop-Mennen and Lindqvist respectively. . 34

2-10 Calculation of the propulsion factor Cpropfor icebreaking ships sailing astern through level ice. All information based on product leaflets of Aker Arctic in Helsinki, Finland 35 2-11 Propeller characteristics for the vessel, based on ABB [17] . . . 35

2-12 Ice strengthening according to the UPCR . . . 40

2-13 Scantlings of the ESS . . . 44

2-14 Break power requirements for the vessel based on resistance and hotel power re-quirements . . . 46

2-15 Comparison of a Wärtsilä, Caterpillar and MAN Diesel dual fuel engine with a break power of 7 to 7.2 MW. All data can be found in the official product guides of the manufactures. . . 47

2-16 Dimensions and weight of the choosen Wärtsilä 34 DF engines. All data from the product guide [9] . . . 47

2-17 Break power of the vessel for different operational scenarios. The cylinder configu-ration refers to the Wärtsilä 34DF engines. All MCR values and hotel requirements are estimations. . . 48

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xii List of Tables

2-18 Fuel consumption of a Wärtsilä 6L34 DF [9, p. 13] . . . 48

2-19 Operational profile times . . . 49

2-20 Break power of the vessel for different operational scenarios. The cylinder configu-ration refers to the Wärtsilä 34DF engines. All MCR values and hotel requirements are estimations. . . 49

3-1 Third iteration results main dimensions . . . 52

3-2 Engine layout, with weights in tonne and arms in m. . . 53

3-3 Tank capacity . . . 54

3-4 Life- and rescue boat requirements . . . 55

3-5 Life- and rescue boat location and size . . . 55

3-6 Requirements of the accommodation . . . 57

3-7 Weights of iteration 3 . . . 59

3-8 Freeboard and trim iteration 3 . . . 60

3-9 Stability results 80% ballast, full load, design draft and minimum freeboard case 61 3-10 Capacities of different load cases after iteration 3, with units in m3 _{for tanks and} TEU for containers . . . 61

3-11 Open water and ice resistance using Holtrop-Mennen and Lindqvist respectively. . 62

3-12 Frame span . . . 67

3-13 Weight estimate of a section of 5.6 m length in the midship . . . 67

3-14 Estimation of factor for lightship weight . . . 68

3-15 Comparison bending moments . . . 68

3-16 Break power requirements for the vessel based on resistance prediction and hotel requirement estimation . . . 72

3-17 Break power of the vessel for different operational scenarios. The cylinder config-uration refers to the Wärtsilä 34DF engines. All MCR values hotel requirements are estimations. . . 72

3-18 Break power of the vessel for different operational scenarios. The cylinder config-uration refers to the Wärtsilä 34DF engines. All MCR values hotel requirements are estimations. . . 72

3-19 Calculation data HVAC . . . 74

3-20 Power requirements for heating the accommodation and the ESS at different am-bient temperatures, Notation ’s’ at the ESS temperature denotes the presence of survivors. . . 74

3-21 Cost comparison of PSV 5000 and AMTSV, rough numbers . . . 75

3-22 Cost build up AMTSV . . . 75

F-1 Ship data during various design stages . . . 126

G-1 Freeboard calculation where "reg." is referring to the regulation number in [11], 2nd iteration . . . 128

G-2 Output of the Holtrop and Mennen program of the TU Delft, 2nd iteration . . . 129

G-3 Intermediate values for the resistance calculations, 2nd iteration . . . 130

G-4 Break power of the vessel for different operational scenarios. The cylinder config-uration refers to the Wärtsilä 34DF engines. All MCR values hotel requirements are estimations. 2nd iteration . . . 130

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List of Tables xiii

G-5 Estimation of scantlings and weight for the open water design . . . 131

G-6 Scantlings and weight estimation of the ice strengthened hull section . . . 132

H-1 Freeboard and bow height calculation where "reg." is referring to the regulation number in [11], 3rd iteration . . . 134

H-2 Output of the Holtrop and Mennen program of the TU Delft, 3rd iteration . . . 135

H-3 Intermediate values for the resistance calculations, 3rd iteration . . . 136

H-4 Break power of the vessel for different operational scenarios. The cylinder config-uration refers to the Wärtsilä 34DF engines. All MCR values hotel requirements are estimations., 3rd iteration . . . 136

H-5 Plate thickness and frames of the structure according to the UPCR . . . 137

H-6 Scantlings and weight estimation of the open water hull section . . . 138

H-7 Scantlings and weight estimation of the ice strengthened hull section . . . 139

I-1 Calculation of the propulsion factor Cpropfor icebreaking ships sailing astern through level ice. All information gathered from the product leaflets of Aker Arctic in Helsinki, Finland, angles are estimated based on general arrangements . . . 143

J-1 Starting point of wind load calculations. . . 147

J-2 Starting point of accommodation floor on ESS calculations. . . 148

J-3 Starting point of the calculations on the ESS wall. . . 149 J-4 LNG tank weight, forces and moments approximated by fixed beam with center load.150 J-5 Scantlings of the ESS, along with stresses on maximum load, excluding safety factors.151

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Preface

The previous reports were mainly realized in Finland. The process of this report is, however, different. During an internship of almost two months at Damen Shipyards Gorinchem we were able to look into their methods and procedures of designing ships. In combination with the topic of Arctic engineering this gives insight for both parties. We received a lot of helpful information about offshore vessels and we provided Damen with an innovative look on designing for the Arctic in relation to their own field of work.

The time frame of this report was tight and the topics to discuss were to be well defined. We started in the beginning of December 2012 and finished this report at the end of January 2013. In this short time we generated a concept design of an AOSV taking into account the Damen standards and the rules and regulations about the Arctic. During the design process we learned more about the importance of assumptions and design choices, since they define in which way a vessel is designed. With the help of the involved partners we were able to proceed with structural and hydrodynamic calculations and specific Arctic engineering subjects, in a successful way.

Our resources were, among others, the standard designs, methods and indicators of Damen, reports of research institutes, class societies, oil companies and websites of the industry. All the information used is quite recent, because the interest in the Arctic research is increasing. This was reinforced by noting several companies involved with AOSV designs with similar design requirements as we came up with.

We hope this report brings you a clear overview of the calculations and considerations, sur-rounding the design of an Arctic Offshore Support Vessel.

Gorinchem,

R.W. Bos (4114620) T.J. Huisman (4080777) M.P.W. Obers (4113187) T. Schaap (4089561) M. van der Zalm (4095316) Version: January 29, 2013

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Acknowledgments

We are honored to thank everyone who made this report possible. After our time in Helsinki, we were warmly welcomed to the Damen main office, where we were provided with a perfect place for five students to work in. It allowed us to call in direct support, which was always generously given. Special thanks to Lucas Zaat and the Offshore and Transport department. From the Delft University of Technology we were supported by Peter de Vos, who gave general guidance on the writing of this and the previous reports as well.

A lot of rules are involved in ship design and Bas Veerman was kind enough to direct our questions to his expert colleagues at DNV. From Marin, Solange van der Werff supported us with feedback and information on winterization.

Our final thanks go out to everybody who has helped us with realizing our dream, the Arctic Minor.

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The fact that the Arctic, more than any other

populated region of the world, requires the

collaboration of so many disciplines and points of view

to be understood at all, is a benefit rather than a

burden.

-Bruce Jackson

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Glossary

AHTS Anchor Handling Tug and Supply vessel. AMTSV Arctic Modular Towing and Supply Vessel. AOSV Arctic Offshore Support Vessel.

BM The distance from the center of buoyance to the metacenter.

Bollar pull An indication of the maximum pulling force that a ship can exert on another ship or an object.

Class Notation Notation to determine applicable rule require-ments for assignment and retention of a cer-tain category of ships.

COG Center of gravity.

Damen Damen Shipyards Group. DAT Design Ambient Temperature.

DNV Det Norske Veritas, classification society. DP Dynamic Positioning, computer-controlled

system to maintain a vessel’s position and heading.

EAR Expanded area ratio, used in propeller char-acterisation.

ESS Extended Super Structure.

FEU Forty-foot equivalent unit, container with a length of 12.2 m.

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xxii Glossary

GA General Arrangement of a ship.

GM The metacentric height, the distance from the center of gravity of the ship to the metacenter, a measure of stability.

HFO Heavy Fuel Oil.

Holtrop-Mennen A widely used approximate power prediction method by J. Holtrop and G.G.J. Mennen. Hydromax A Formsys program: "Hydromax - Intact and

Damaged Hydrostatics and Stability".

IBC Code International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk .

KB The distance from the keel to the center of buoyancy.

KG The distance from the keel to the center of gravity of the ship.

Life Boat a craft capable of sustaining the lives of per-sons in distress from the time of abandoning the ship..

Lindqvist Metonymy for an empirical formula to predict ice resistance, after its inventor.

Liquid mud A type of drilling fluid used for offshore drilling.

LIWL Lower Ice Water Line.

LNG Liquid Natural Gas.

Marin Maritime Research Institute Netherlands. MARPOL International Convention for the Prevention

of Pollution from Ships.

Maxsurf A Formsys program: "Maxsurf - 3D hull, su-perstructure and appendage modelling". MCR Maximum Continuous Rating.

MDO Marine Diesel Oil.

MOB Man Over Board boat.

Operational Profile Quantitative characterization of how a vessel will be used.

P/D Pitch diameter ratio, used in propeller char-acterisation.

PC Polar class.

per Pollutant emission ratio. Potable water Drink water or Fresh water.

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Glossary xxiii

PSV Platform Supply Vessel.

reg. Regulation.

Rescue Boat Man over board boat; a boat designed to res-cue persons in distress and to marshal survival craft.

Riska Metonymy for an empirical formula to predict ice resistance, after its inventor, based upon Lindqvist.

ROV Remote Operated Vehicle. RPM Revolutions per minute. sfc Specific fuel consumption. SOLAS Safety of Lives at Sea. SOS Safety distress signal. spe Specific pollutant emission. SSV Standby Safety Vessel.

SWATH Small-waterplane-area twin hull.

SWOT Model for evaluating Strengths, Weaknesses, Opportunities, and Threats of a certain con-cept.

TEU Twenty-foot equivalent unit, container with a length of 6.1 m.

UIWL Upper Ice Water Line. UPCR Unified Polar Class Rules. VCG Vertical center of gravity.

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Nomenclature

Latin Letters

AF Hull area factor [-]

AR Load patch aspect ratio [-]

B Breadth [m]

b Breadth of the area under consideration of UPCR

[m]

bbow Breadth of the bow area under consideration of UPCR

[m]

bnonbow Breadth of the non bow area under

considera-tion of UPCR

[m]

BM Distance between the center of buoyancy and metacenter

[m]

C1 Constant in the level ice prediction of Riska et

al. 1997

[-]

c1 Constant for the plate thickness calculation of

FSICR

[-]

C2 Constant in the level ice prediction of Riska et

al. 1997

[-]

ca Constant for the plate thickness calculation of FSICR

[-]

cd Constant for the plate thickness calculation of

FSICR

[-]

cp Constant for the minimum engine output of DNV

[-]

cs Constant for the minimum engine output of DNV

[-]

CG Distance between the keel and the center of gravity of a certain weight

[m]

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xxvi Nomenclature

Dp Propeller diameter [m]

CFc Constant for the pressure calculation of UPCR [N]

F Force [N]

f1 Constant for the plate thickness calculation of

FSICR

[-]

FSICR

[-]

FSICR

[-]

FSICR

[-]

Fi Force at position i of UPCR [N]

f1 Constant in the level ice prediction of Riska et

al. 1997

[N/m3]

al. 1997

[N/m3]

al. 1997

[N/m3]

al. 1997

[N/m3]

Fbow Force at the bow [N]

Fnonbow Force at the non bow area [N]

f ai Factor fa at position i [N]

F n Froude number [-]

F nh Ice thickness based Froude number [-]

g Gravitational constant [m/s2]

g1 Constant in the level ice prediction of Riska et

al. 1997

[_m/s·mN 1.5]

al. 1997

[_m/s·mN 2]

al. 1997

[_m/s·mN 2.5]

GM Distance between the center of gravity and metacenter

[m]

h Height of load area in the FSICR [m]

hi Ice thickness [m]

i Integer [-]

IN Ice class number according to DNV [-]

IR Icing rate [m/h]

Ke Constant for the effect of the propeller [-]

KQ Torque coefficient [-]

KT Trust coefficient [-]

KB Distance between the keel and center of buoy-ancy

[m]

KG Distance between the keel and the center of gravity

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Nomenclature xxvii

l Span of the frame [-]

Lpp Length between perpendicular [m]

Lwl Waterline length [m]

m Constant for the plate thickness calculation of FSICR

[-]

mt Constant for the plate thickness calculation of FSICR

[-]

n Revolutions rounds per minute[s−1]

P Pressure [N/m2]

p Ice pressure [N/m2]

Pi Pressure at position i [N/m2]

pavg Average ice pressure [N/m2]

Pbow Pressure at the bow [N/m2]

PB Brake power [W]

PDN V Minimum engine output of DNV [-]

PD Delivered power [W]

PF SICR Minimum engine output of FSICR [-]

Ppl Pressure on the plating in the FSICR [N/m2]

P P Fp Peak pressure factor [-]

P R Predictor of the icing conditions [-]

Q Line Load of UPCR [N/m]

Qi Line Load at position i of UPCR [N/m]

Qbow Line Load at the bow of UPCR [N/m]

Rb Resistance component due to buoyancy of the ice

[N]

Rc Resistance component due to clearing the ice [N]

Ri Resistance in Ice [N]

Rt Total resistance in Ice [N]

Rbending Bending Component of the Lindqvist 1989

method

[N]

Rbr Resistance component due to breaking the ice [N]

RCH Channel ice resistance [N]

Rcrushing Crushing Component of the Lindqvist 1989

method

[N]

Row Open water resistance [N]

Rsubmersion Submersion Component of the Lindqvist 1989

method [N] s Frame spacing [m] T Draught [m] T Temperature [K] t Plate thickness [m]

t1 Material design temperature [K]

t2 Extreme design temperature [K]

Ta Air temperature [K]

tb Begin time window [s]

tc Plate thickness increment [m]

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xxviii Nomenclature

Tf Temperature of saline ice at freezing point [K]

Tw Temperature of seawater [K]

TN ET Net thrust [N]

tnet Net plate thickness [m]

TP U LL Bollard Pull [N]

ts Plate thickness addition for Corrosion/ Abra-sion

[m]

Va Wind speed [m/s]

vs Velocity of the ship [m/s]

vow Maximum open water speed [m/s]

w Width of the area under consideration [m]

Wi Weight rate of the ice accretion [kg/h]

wbow Width of the bow area under consideration of

UPCR

[m]

wnonbow Width of the non bow area under consideration

of UPCR

[m]

Greek Letters

α Waterline entrance angle [deg]

δρ Difference in density between ice and water [kg/m3]

ηT RM Transmission efficiency [-]

µ Friction between hull and ice [-]

φ Stem angle [deg]

ψ Angle between normal of the surface and ver-tical vector

[deg]

ρice Density of sea ice [kg/m3]

ρw Density of sea water [kg/m3]

σy Yield strength [N/m2]

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Introduction

In the literature survey of the Arctic Minor, the need for an Arctic Offshore Support Vessel (AOSV) is clearly stated. A comparison was made with the requirements of such a vessel and three Damen designs. Some adaptations were recommended to enable the vessel to sail through ice, but the need for a new design was clear. This report aims to present a new and innovative design of an AOSV, encompassing state of the art technologies to ensure safe navigation and operation.

Target

The total study on AOSVs is composed of three reports, with the first report the literature study and the second report an examination of three Damen offshore vessels. This is the third and final report, based on the acquired knowledge and the conclusions drawn in the previous reports, to give the considerations, assumptions, working process and results of the concept design of an AOSV. The design requirements set in this report are not completely uniform with those in the literature report because of new insights and assumptions. The final result is the general arrangement of an Arctic Modular Towing and Supply Vessel (AMTSV) for which the hull form and layout are optimized for open water and ice conditions.

To be able to read the report, one should have the shipbuilding knowledge of a maritime engineering bachelor student. That is, basic knowledge about constructions, hydrodynamics and propulsion installations, but also about the Arctic and its perils. The background about this can be found in the previous reports.

Scope of Work

From the conclusions drawn in the literature survey, the basic requirements of the ship, the scope of work can be defined. In general the report is limited to a concept design with one, two or at some points three iterations in the theoretical design spiral. Some specific Arctic subjects are dealt with in more detail. The starting point of the design is the Damen PSV

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2 Introduction

5000, which is used as an inspiration for the open water and offshore capabilities of the new design.

A concept design is made, where educated estimations are made about the ship. The data to do this comes from widespread methods in shipbuilding, as the Holtrop-Mennen method; methods discussed in the literature or comparison report, such as Lindqvists formulas; or by data from Damen, often confidential and therefore omitted from this report. When no data is present basic calculations are made on the subject, or comparable ships and projects are reviewed. There was no clear set demand for this design, therefore the designers themselves have set up the requirements for the vessel.

Structure

The structure of the report is equal to the steps of the design spiral. An example of the spiral is shown in figure 1, it is an idealistic representation of how the steps of building a ship are to be taken. With this spiral, several iterations will be made before presenting the final design. The design spiral steps are not all exactly followed and completed, new insights during one step had design implications on a previous one.

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Chapter 1 Early Design, 1st iteration

This chapter gives a short overview of the operational profile that was chosen in the literature study and comparison report. Also the required class notations for this operational profile are listed. Section 1-2 focuses on innovations for an Arctic offshore supply vessel, a first general arrangement is made and described in section 1-3.

1-1

Owner Requirements

In this section the mission, operational profile and detailed owner requirements for the AOSV are presented. The owner requirements do not change unless otherwise stated for the different iteration phases. The section is structured as follows, in subsection 1-1-1 the mission of the vessel is defined. Based on this mission an operational profile is derived in subsection 1-1-2. To ensure that the mission and operational profile can be fulfilled detailed owner require-ments such as cargo capacity, design speed and class requirerequire-ments are defined in detailed requirements in subsection 1-1-3.

1-1-1 Mission

The AOSV should be capable of supporting offshore operations in the Arctic by being able to transport supplies, acting as standby and ice management vessel, perform towing tasks and having a good performance in ice and open water. It should also be capable of containing the consequences of an oil rig disaster by means of fire fighting, oil spill recovery and rescue operations. The vessel is designed for worldwide operations to support offshore installations, in open waters and first year ice.

1-1-2 Operational profile

In the comparison report a general winter scenario is given [2]. This is used again to give an indication of the endurance and fuel rates. Figure 1-1 gives the route from Murmansk

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4 Early Design, 1st iteration

to a potential rig, see [3, figure B-2], at the maximum annually ice extent. One trip from Murmansk to the potential platform will take 113 hours in the winter time, of which 62 hours through ice and 51 through open water at the design speeds.

Figure 1-1: Route from Murmansk to a potential offshore platform. Adapted from [4]

The estimated winter operational profile is given below:

• 60% support tasks of which 80% ice management / standby tasks and 20% supply of platform at DP

• 15% voyage in open water of which 55% loaded and 45% empty • 20% voyage in ice of which 55% loaded and 45% empty

• 5% port time

This operational profile is, however, not bound to the Barents Sea scenario in figure 1-1 as the vessel will also be able to operate in the Baffin Bay and Beaufort Sea with a shorter time window, as explained in [3, chapter 13]. The operational profile of the ship will also be different in summer and winter.

In the summer season the route to the potential oil rig is ice free. The vessel has therefore, next to the winter scenario, a summer operational profile listed below:

• 80% of the time at transit

• 15% of the time at dynamic position • 5% of the time in port

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1-1 Owner Requirements 5

This summer scenario is adapted from the operational profile of the Damen PSV 3300 [2, chapter 1]. It is assumed that the winter profile is the harsher profile compared to the summer scenario. For further calculations, for example the endurance calculation, the winter scenario is therefore chosen. The endurance in the summer time is higher than in the winter scenario.

1-1-3 Detailed requirements

Based on the mission of the ship, detailed requirements are obtained for the design for the vessel. The requirements are not given by a shipowner, but were initially chosen according to the literature study [3] and reference vessels as seen in table 1-3. More specific requirements for the cargo space and exact class notations were established iterative throughout the design process.

• The vessel has to sail through level ice with an average level ice thickness of 1.6 m with a speed of 3 kn. The maximum ice thickness which the vessel is capable of going through will be higher, but at lower speeds. The vessel will also be able to penetrate ridges without thickness restriction.

• The values for range and speed are based on the specifications of reference offshore vessels, and are given in table 1-3.

• The chosen class notations follow from the literature study [3, chapter 13]. These class notations are in accordance with the operational profile and mission. However, during the design process was decided to focus on platform support vessels without taking into account the anchor handling, see section 1-2.

• Cargo capacities are determined iteratively.

• The chosen class notations for the cold conditions are chosen based on [2, figure 2.1]. The vessel should also be able to operate in, for instance, the Baffin Bay where the design temperature should be lower than in the Barents Sea.

• A maximum rule length of 99.9 m is used, because when the ships is longer it has to comply with a different package of rules. This length is from the fore side of the stem to the axis of the rudder stock at 85% of the minimum depth.

An overview of the detailed requirements is listed in table 1-1. This list is explained further in the following chapters.

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Table 1-1: Design requirements

Area Value Unit

Barents Sea (year round) Beaufort Sea (April - November) Baffin Bay (May - December)

Ice conditions

Design level ice thickness 1.6 m

Maximum level ice thickness 2 m

Ridges all

Iceberg handling and towing

Speed

Design speed open water 14 kn

Design speed in design level ice 3 kn

Bollard Pull 140 t

Endurance 30 days

Length 99.9 m

Cargo capacities

Ballast water / drill water 1800 m3

Service fuel oil 700 m3

Cargo fuel oil / base oil 1500 m3

Potable water Service 400 m3

Potable water Cargo 700 m3

Drill water 1400 m3

Dry bulk 310 m3

Liquid mud 1100 m3

Total cargo capacity 7910 m3

Accomodation Survivors 150 People Crew 35 People Class Notation PC4 ICEBREAKER WINTERIZED ARCTIC (-35,-55) DAT (-35) Towing Supply DYNPOS AUTR STANDBY VESSEL (S) Fire Figher II OILREC CLEAN DESIGN

Modulair, containerized design

OILREC Various cargo Standby equipment Extra fuel

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1-2 Innovation and design choices 7

1-2

Innovation and design choices

Several ideas and concepts about hull forms, general arrangements and equipment of an AOSV were formed during a brain storm session. This section discusses the initial ideas and gives the ensuing design choices with their assumptions.

1-2-1 Initial ideas

All mentioned ideas are to be found in appendix B. The most interesting ideas are reviewed in appendix C according to the SWOT concept, see figure 1-2. With this model all positive and negative factors of a certain idea are mentioned.

Figure 1-2: SWOT model used for the analysis and appreciation of the ideas. Adapted from [5]

1-2-2 Design choices

This section gives an overview of the choices that were made and the argumentation in-volved. Feasible concepts are compared with each other and design choices are made based on advantages and disadvantages.

Double acting hull vs Double draft hull

A double draft hull means the vessel is sailing though ice on a lower draft, because a lower freeboard is assumed to be acceptable. When sailing through open water, the vessel will be at the higher draft. Therefore the vessel can be optimized on ice breaking at the lower draft and on good open water behavior at the higher draft. The double acting hull concept means while going through open water the conventional bow is used, but when encountering ice the ship will be turned and goes stern first. The conventional bow is therefore optimized on open water performance while the stern has a special ice breaking form.

The double acting hull concept is chosen because of difficulties with the double draft princi-ple. Pitfalls of the double draft are the requirements for large ballast tanks and the greater

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resistance at the higher draft. Also, the problems the double draft hopes to solve, slamming for instance, are still present at a high sea state.

For structural reasons, the ice breaking bow will be regarded as bow of the ship in ice con-ditions. This makes the stern the open water bow. It is also possible to give the open water bow lower ice class compared to the ice bow. However, the ice breaking bow will be regarded as bow of the ship because then it is clear that the vessel will only sail this way through ice since this proved to be more efficient [3]. It is assumed that one can classify an AOSV with the ice bow first. The open water bow does comply with the conventional class requirements for open water conditions.

Propeller and thruster innovations

In this paragraph the possible types of propellers and thrusters are discussed.

Retractable Thrusters - Several configurations of retractable thrusters are possible:

1. At the bow instead of conventional tunnel thrusters

2. In addition to the two main thrusters, retractable thrusters can be installed for DP operations

3. Retractable open water and ice pods, four in total. In case of towing operations all pods are used for a high bollard pull

A retractable thruster is used in the design as open water bow thruster. This decreases the open water resistance, because the flow around the hull is more optimized than with the open water bow thrusters. Still a conventional tunnel thruster is used to provide thrust at small water depths. The retractable thruster needs minor ice strengthening, since it is protected by the hull and not used in heavy ice conditions.

Retractable Nozzle - For ice operations a nozzle is not recommended because of clogging issues.

Also the milling advantages of the propellers are reduced. However, a nozzle increases the thrust and therefore efficiency at low speeds and can be used to increase the bollard pull. To utilize the advantages of both a nozzle and milling a retractable nozzle could be used. At high speeds and severe ice conditions the nozzle could be retracted.

Contra Rotating Propeller - For contra rotating propellers also several configurations are

possible.

1. One conventional shaft line with propeller with an azimuth thruster behind 2. A propeller at both ends of a azimuth podded propulsor

3. Two propellers directly behind each other on one end of the azimuth

The need for the retractable pod, nozzle and contra rotating propellers is taken away when the requirement for a high bollard pull is dropped. To do so, the assumption has to be made that anchor handling operations are not done by this vessel. With this assumption a purpose built anchor handler will have to do all of these operations. For the vessel to perform

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ice management, 70 - 140 ton bollard pull is required [3], which can be achieved without a nozzle.

Propeller Change - When a vessel is sailing through open water a different propeller is needed

compared to when sailing though ice. With a propeller change, the summer propeller can be changed with an ice propeller to increase efficiency in different seasons or operations. This operation should be possible with sufficient crane capacity and a ROV.

All concepts are either relatively new or non-existent. Choosing one of these will lead to more uncertainties in the design and the advantages in ice are not well known. More research should be done on the advantages. Therefore the choice for a conventional azimuth propulsor is made. These are known to perform well in ice and this choice reduces the complexity of the design.

Winch system

The double acting winch features a winch that can be used in both directions simply by sending the cable the other way. This concept does not exist at the moment. Since the cable starts at the top of the drum at one end and at the bottom at the other there is a height difference in the different directions. This height difference is an advantage as the front mooring deck needs to be above the main deck to avoid constant flooding when going through open water in high sea states. Detailed research should prove the assumption that the double acting which will be actually used since the open water bow is also ice strengthened. For instance, iceberg towing is not possible in compact ice, only in open water or managed broken ice. If the winch is placed outside, it might freeze and therefore require extra strengthening. When it is placed inside on the other hand, the crew can work in an enclosed area and is protected against the weather conditions.

LNG

As can be seen in [3, p.47-48], LNG is a cleaner and cheaper fuel than diesel oil. The main disadvantage is that LNG uses 3-5 times more storage space than fuel oil. However, when these tanks are intelligently placed this does not have to be an obstruction. Therefore the ship will be fitted with LNG.

Superstructure at front, back, side or midship

As with conventional offshore support vessels, the superstructure is placed on the open water bow of the ship, this to minimize spray on the deck. The superstructure protects the deck in cold environments without ice. The size and shape of the superstructure is to be based on ships reviewed in the comparison report and later changed in the different iteration steps [2].

Waste heat management for deck heating

The engine and several other big components in the ship produce considerable amounts of heat. This heat is usually discarded in the form of exhaust gases or even by active cooling

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with seawater. The waste heat can be recovered by means of a heat exchanger and used to warm the superstructure and open decks for de-icing. The usage of LNG allows further cooling of the exhaust gases than with fuel oil, because of to the absence of sulfur.

Paint arrangements

The color of a surface affects how much energy it absorbs. A dark deck area will absorb energy from light and warm up, the same goes for a superstructure. The effect on the emission of energy is not as obvious and requires more research, which is out of the scope of work. Because of the long duration of both day and night, this option will be used in the concept to ensure further considerations.

Fully coverable decks vs Two stage deck

The whole deck can be covered, meaning all the equipment and the crew are not subjected to the cold environment. Another option is to cover the deck partially to also utilize the advantages of an open working deck. Some of the supplies the ship is carrying will have to be covered. Also, coverage of the decks will provide the crew with a safe working environment, should the need for work on deck occur. To give the ship a Winterized Arctic notation a helicopter landing facility is required [3].

The combination of these factors leads to the choice of the two stage deck, from here on called Extended Super Structure (ESS). This allows the helicopter to land on the fore deck and be stored in the ESS, should this be necessary. Besides that, the large open space in the ESS can be used as survivor area, when the doors are closed and installed heating is used.

Modular approach

A container hold can be used to store containers to equip the ship for its specific task. Possibilities are:

1. Extension of the cargo capacity 2. Additional LNG storage

3. Equipment required for standby and rescue tasks 4. Oil recovery systems

5. Extra power generation

The hatch cover for this hold has to be watertight, winterized and designed for high cargo loads. In this stage of design it is therefore assumed that the hatch covers can only be removed by cranes in the port. The modular area will not be changed on every journey, but more likely when there is a change of charterer or once in a year. Regular containers are to be placed on the deck. Ship operations vary over time. The operational modular approach is used to enhance reconfigurability and flexibility of the vessel. Because the ship has some supplies that have to be taken along at all times, permanent tanks will also be provided.

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Active stability

Using active stability reduces rolling of the vessel and therefore increases comfort. For this purpose fins or anti-rolling tanks can be used, these fins can be retractable. Bilge keels or fins are not desirable in the Arctic, due to ice coming under the vessel, anti-rolling tanks are installed on the vessel.

Rescue slide

An emergency slide is used in case evacuation is required in airplanes. To get away from the superstructure from the ship in case of emergency, a similar rescue slide will be provided, analogous to the ones used on aircrafts. At the end of the slide, a rescue boat, raft or amphibious vehicle should be available. This vehicle should provide shelter and contain food an water for the survivors. While the rescue slide is not always usable, it will not take much space and is therefore included in the design.

De-icing firefighting

Using the existing fire fighting systems and sprinklers the decks and rescue equipment are to be deiced. More research on the allowable use of these fluids needs to be done.

1-2-3 Summary of design choices

The design choices that are used in the concept vessel are listed below. • Double Acting Ship concept

• Retractable bow thruster instead of tunnel thruster • Podded azimuth propulsion

• No need for usage of nozzles • Usage of LNG as fuel • Double acting winch

• Superstructure comparable to reference ships • Waste heat recovery for heating purposes • Partial covered deck (ESS)

• Modular approach using container hold • Active stability using anti-rolling tank • Usage of rescue slide in ice conditions

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1-3

General arrangement

In this chapter the design considerations about the initial general arrangement are given. The general arrangement can be divided into several main components of certain dimensions. This first general arrangement does not include small equipment and specified arrangements, but is intended to give insight in the concept design.

1-3-1 Main Dimensions

The main dimensions are chosen iterative throughout the design. The length can be considered the first choice in this design process.

Length

First estimates of lengths of parts of the general arrangement are given in table 1-2. Also the explanations for the choices are given in the same table.

Table 1-2: First estimations of dimensions for use in the general arrangement

Tween Deck [m] Explanation Ballast / fore peak 4

Bow thruster room 14 Reference ships, probably more and heavier thrusters Control/Engine 23 Empirical formula + LNG and heating equipment Cargo 28 Same as the ESS, the bulkhead gives strength to the

ESS

Containers 15 One row modular equipment in containers = 12.2m + room for connections and handling

Thruster / Pod room 15 Ice strengthened pods require more space than con-ventional. Also the room is bigger than conventional rooms because the vessel will need more power.

Total 99

Main Deck

Fore peak (store) 5 Different from tween deck because of bow angle Accommodation 21 Conventional accommodation 12 m + LNG tanks 8 m

+ extra Arctic equipment rooms + rescue means and equipment

Winch 7 Winch + auxiliary systems and spooling devices + arrangement for changing towing direction

ESS 28 Two FEU in length = 2 · 12.2m + space to handle the containers. The towing winch installation is also located here

Open deck 38 Hatch cover for the containers

Total 99

The maximum length of 99.9 m is used in table 1-3 to give an indication of the other dimensions and cargo capacities. This length follows from the DNV rules. Ships below 100 m are to be

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1-3 General arrangement 13

designed with a different set of rules than ships above 100 m. The table is based on equivalent open water vessels because only minor reference material about Arctic vessels is available. The dimensions and tank capacities are given by taking the additional arctic factors into account which are discussed in the following paragraphs.

Table 1-3: Main dimensions and tank capacities

Main Dimensions Value Unit

Length 99.9 m Beam 21.5 m Depth 8.5 m Draught 7 m Deadweight 6000 t Displacement 10000 m3 Deck area 1200 m2

Deck load at 1m above deck 4500 t

Power 10 MW

Crew 35 People

Cargo capacities Value Unit Ballast water / drill water 1800 m3

Service fuel oil 700 m3

Cargo fuel oil / base oil 1500 m3

Potable water Service 400 m3

Potable water Cargo 700 m3

Drill water 1400 m3

Dry bulk 310 m3

Liquid mud 1100 m3

Total cargo capacity 7910 m3

Beam, Depth and Draft

As can be seen in figure 1-3, there are no open water vessels of 100 m in length. The trend lines are extrapolated giving a resulting beam of 21.5 m, depth of 8.5 m and draught of 7.0 m.

Deadweight

Due to the Arctic conditions it will take more time until the vessel reaches the platform, the travel distance is bigger and the average speed is lower. This means the vessel needs to have more endurance and cargo capacity. This increases the required deadweight. The extrapolation of figure D-1 gives a deadweight of 6000 t.

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Figure 1-3: Length - Breadth

Displacement

In figure D-2 the chosen displacement is displayed. The displacement is checked with the ratio between the deadweight and length, the graph is given in figure D-3. It is assumed that this ratio will be slightly below the assumed linear trend line because of the extra lightweight on the ship due to the ice strengthening. The ratio was chosen 10% above the expected value giving a DWT/LWT ratio of 0.6 and a displacement of 10000 t.

Deck area

As can be seen in figure D-4, the deck area is almost linearly dependent on the length. This gives the concept vessel a deck area of 1200 m2.

Deck cargo

When the vessel is sailing in Arctic conditions ice accretion is possible which will increase the deck load as can be seen in figure D-5. With the ice accretion taken into account a deck load of 4500 t is assumed to be sufficient [2], where 3800 t would be expected based on the trend.

Power

The power trend line can be found in figure D-6 which shows a relatively scattered plot. The chosen power of 10 MW is still far above the trend because of the ice resistance. This power

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is as first estimation chosen using the knowledge from [2, 3].

Crew

The plot of the amount of crew as seen in figure D-7 shows great scatter, because it is very dependent on rules and the required operations instead of the length of the vessel. However assuming a linear trend the crew can be estimated to 25 people. Colder environment requires more people because working shifts are shorter as explained in [3]. Therefore the first estimate of the required crew is set at 35 people.

1-3-2 Arrangement

In this subsection the placing of the chosen innovations is discussed and a general arrangement is derived. The class notation CLEAN DESIGN is taken into account when determining the placings.

Extended SuperStructure (ESS)

To provide the crew with an enclosed working environment and allow supplies to be stored inside, the superstructure is extended. Products and equipment that have to be winterized can be stored. The length of the ESS is sufficient to store two FEUs in the length and provide enough space for container and cargo handling. Towing operations forwards and backwards are still possible with containers on deck.

The area of the ESS can also be used for other operations. In case of a rescue operation the ESS can be used as a survivor area. Heating is installed to function as such area. In remote areas when the ship is performing standby or ice management tasks it can come in handy if a helicopter can land on the aft deck and can be moved to the ESS for storage, refueling and maintains. While a helicopter is on the vessel no towing with the open water side first is possible, towing with the ice breaking side first is still possible. In this stage also rescue operations are possible.

Engine room

Based on the Damen AHTS 200, which has an installed power of 13440 kW, the engine room would have to be around 20 x 20 x 6.5 m including service fuel tanks. The configuration is two main engines with generators and two smaller ones.

The engine room is placed below the accommodation. This is done to minimize walking times and maximize available space. The shape of the ship does not allow placing the engines directly in front or next to the pods. When using a diesel electric drive this choice does not require any shafts to the propulsors. Another advantage of this location is the possibility of reusing heat generated in the engine room for heating the accommodation with short distances and minimal losses. The final advantage when taking the current general arrangement into consideration is the short distance to the fuel storage.

The pod room is located in the aft below the main deck. There are also several switchboards around here to reduce the required cables running through the ship.

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LNG tanks

To make an environmentally friendly design it is chosen to use dual fuel engines that can run on LNG, MDO and HFO. The storage of LNG has to be under compression in cylindrical tanks. The required LNG capacity can be calculated by assuming that the ship operates 30 days non stop at 80% MCR on LNG fuel. With an engine power of 10 MW a total of 20.7 TJ is needed. With an energetic value of 49 M J/kg [6] and a density of 410- 500 kg/m3_{, 1032}

m3 LNG are needed. In a first estimation the LNG tanks have an inner diameter of 7 and 9 m respectively and a height of at least 12 m, which leads to a tank capacity of 1225 m3. It is assumed that the outside diameter of the tanks is 1 m more than the inner diameter and the outside height is around 2 m more than the inner height. The dimensions of the LNG storage tanks are therefore 8 m by 14 m and 10 m by 14 m. A couple of different options are discussed for placing the LNG tanks.

1. Option 1

Two tanks are placed next to each other at the end of the accommodation area. The tanks have to be small enough to ensure easy passing at port and starboard side. 2. Option 2

Placement of multiple tanks on starboard and port side next to the ESS. The tanks are not located in the accommodation area, but the ESS width would be decreased. Next to that multiple small tanks with the same capacity as a single tank require more additional equipment.

3. Option 3

Placing of two tanks of different diameters behind each other in the accommodation area and was assumed to be the best, because it is the most space efficient option. The tanks are centrally integrated in the accommodation design and shall start on the main deck and stop above the bridge.

Winch

The conventional way to place a winch on a towing vessel is behind the superstructure or on the fore deck. Figure 1-4 shows the different places for the winch. The winch can be placed in the ESS, below decks and above deck, aft and at the bow.

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It is preferred that during operation and storage of the winch is fully covered. Because the ESS gives a lot of extra indoor space, the winch will be placed here. The exact location is at the start of the accommodation. For forward towing the line is led through the accommo-dation which enables the crew to operate the winch in a fully enclosed environment. Towing backwards with the open water bow first only occurs in open water and does therefore not have to be covered. The towing line is led across the deck to the ice bow. There will be cameras in the towing operations area, so the person who is operating the winch can see how the movements effect the cable.

An estimate of the capacity of the winch is according to Damen 2.2 times the required pull of the winch. The bollard pull of the vessel will be about 140 ton which gives a 300 ton winch. The breadth of the winch is 7 meters, the length 6.6 meters and the height 5.6 meters estimated based on Damen reference ships.

Bridge

For the fire fighting and standby vessel notation clear visibility is needed. The requirements for the bridge and lighting can be met by placing an operational bridge facing the ice bow. The bridge needs to be connected to the open water bridge and all operations need to be controlled from there. A sufficient light and camera set up needs to ensure good visibility even in harsh conditions.

Rescue zone

In the first design stage the rescue zone is placed at the aft part of the accommodation area and ends before the ESS. The length of the zone is estimated as 10 meter. The main deck accommodation area is dedicated to the decontamination area and the hospital in that zone. On the decks above, survivor arrangements are made. Furthermore, the ESS can be heated and equipped for taking the survivors.

Oil recovery system

An oil recovery system can be optionally installed. The required equipment can be placed in the modular container hold. The operation can be supervised from the bridge, which allows a good overall view. A conventional oil recovery system with skimmers can be placed on the port and starboard side of the vessel. This system can be used in open water. To recover oil in ice another system is needed, which is not yet available [3].

Helicopter facilities

The helicopter landing area is assumed to be possible on open main deck in case of emergency. The ESS should be equipped according to the rules and regulations for hangars on board ships. After landing the helicopter can be placed inside the ESS. It is assumed that helicopter landing and storage is only needed when the ship is on standby or ice management duties. In these operations the ESS and open deck are empty and a helicopter should be able to land.

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1-3-3 Summary of General Arrangement iteration 1

The dimensions given in table 1-2, together with the assumptions and decisions made in this chapter, are processed in a general arrangement, see figure 1-5. The general arrangement of the Damen PSV5000 is used as reference to give an indication of the assumptions and decisions made in this chapter. No attention was paid to the exact dimensions or tank arrangements. The next chapter gives the considerations about this general arrangement and gives the second general arrangement in which more details are processed.

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1-3 General a rrange ment 19

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Chapter 2 2nd Design Iteration

In this chapter the main changes compared to the first iteration and their argumentation are displayed. Only the changes compared to iteration 1 in chapter 1-3 are mentioned in this chapter, but also subjects that are investigated more into detail. A new iteration was started, because the LNG tank placement was considered not good enough. In a brainstorm session multiple new general arrangements have been drawn and can be found in appendix E. Main advantages of this concept, shown at the end of section 2-2 compared to the one shown in figure 1-5 are:

• The accommodation and superstructure are a standard design with a proven production process.

• No space losses in the accommodation due to a LNG tank.

• Effective use of available spaces, such as deck, ESS and towing arrangement. • Bridge positioned on top of the ESS and has a wide view over the open deck. • Large bridge design to ensure all operations can be handled from inside.

• The rescue zone is easy accessible and close together, there are no long walkways. The sections of this chapter are based on the entries of the design spiral given in the intro-duction.

2-1

Hull

The shape of the hull defines for a large part the stability and resistance of the ship. Keeping this in mind, the hull is designed using special hull design software Maxsurf and HydroMax,

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22 2nd Design Iteration

Table 2-1: Second iteration results main dimensions

Main Dimensions Value Unit Length waterline 97.7 m

Beam 21.5 m

Depth 8.5 m

Draught 7.0 m

Displacement 10500 m3

which allows the designer to calculate, among others, stability and displacement, while design-ing the vessel. Durdesign-ing the process of modeldesign-ing the vessel in the programs the main dimensions changed.

The ship uses the double acting hull concept. The bow is optimized for ice, by using a spoon shaped bow. For a good open water performance the stern, the open water bow, is shaped like the Damen vessels, which has good performance in open water. The flat shape of the ice bow allows the podded propulsors to be fitted. The line drawings can be found in appendix K. The main dimensions that are used for the second iteration are given in table 2-1.

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2-2

General arrangement

In this section the design considerations about the first general arrangement are given and the changes are processed in a second general arrangement. Some parts are also worked out more in detail in this general arrangement compared to the first general arrangement. The general arrangement from the second iteration can be found at the end of this chapter.

2-2-1 Frame spacing

First estimates of the lengths of all parts of the ship are to be found in table 1-2. How-ever, frame spacing and requirements of watertight bulkheads were not taken into account. Therefore frame spacings are chosen and given in table 2-2.

Table 2-2: Frame spacings

Section Frame spacing [m] Explanation

Superstructure 0.7 Optimized for Damen ships, standard dimensions

Midship 0.6 Need for ice strengthening, assumed more effective

with respect to weight

Ice bow 0.4 Heavy ice strengthening, big frames on 0.8 m, small

frames between them. Considered to be the smallest frame spacing for efficient production

Bulkheads are placed taking into account the frame spacing. Therefore the lengths are changed slightly. The new lengths can be seen in the general arrangement at the end of this chapter.

2-2-2 Tank capacities

The tank arrangement is also adjusted to the frame spacing. The estimated tank capacities are shown in table 2-3. For the deadweight estimations the density of the drybulk and liquid mud is estimated according to Damen to 2.5 t/m3, fuel oil at 0.84 t/m3 and a TEU at 20 t. The room above the passageway in the modular container area, is not a tank but assigned as control and connection area. The passageway is also used for the piping and cables. Despite the LNG, normal service fuel is needed to increase redundancy. These tanks are located next to the engine rooms. It is assumed that ballast water can be exchanged with drill water and that the fuel oil tanks can be used for bore oil and recovered oil if necessary. These capacities are assumed to be feasible and likely to be set as design requirement. Therefore the requirements in table 1-1 are set to the estimated capacities.

The opportunity of this design is that only a minor amount of service fuel oil is needed and more cargo space for oils and other liquids are available. However, due to the modular cargo hold the capacity of dry bulk and liquid mud is less compared with the initial estimates in table 1-3.

To clean the dry cargo and liquid mud tanks the walls of the tank have to be smooth. The construction of the tanks is placed in the surrounding fuel tanks. The liquid mud tanks

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24 2nd Design Iteration

Table 2-3: Tank capacity

Fore ship Value Unit Ballast water 120 m3 Fresh water 228 m3 Fresh water 336 m3 Engine room Fresh water 348 m3 Ballast water 104 m3

Fuel Oil (service) 303 m3

Cargo hold

Dry Bulk (4x66) 265 m3

Liquid mud (6x156) 936 m3

Fuel oil 590 m3

Containers

Containers EES 36 TEU Modular Containers 24 TEU Aft ship Fuel Oil 799 m3 Ballast water Double bottom 1550 m3 Double hull 120 m3 TOTAL Fresh water 912 m3 Ballast water 1894 m3 Fuel oil 1692 m3