KNUD E. HANSEN A/S

Design of Wind Turbine Installation Vessel Pacific Orca for Swire Blue Ocean

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KNUD E. HANSEN A/S

Design of Wind Turbine Installation Vessel Pacific Orca for Swire Blue Ocean

An introduction to the technical aspects of the design of the Wind Turbine Installation Vessels Pacific Orca & Pacific OspreybySenior Naval Architect Jesper Kanstrup, Knud E. Hansen A/S

• Owner’s design requirements• The development of Knud E. Hansen’s designs• Legs, spud cans and jacking system• Cranes• Thrusters• Engine arrangement• Cargo deck and sea fastening• Accommodation

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The Starting Point

The starting point was the world’s first purpose-built wind turbine installation vessel “Resolution”, a 130 m long and 38 m wide vessel with 6 square plate legs, which KEH had developed for “Marine Projects International” in 2001 and was delivered in 2003

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Owner’s Design Requirements

Owner’s initial design requirement:

Water depth for jacking: 45 m @ 10 m air gab, 5 m sea bed penetrationCargo deck space: sufficient for ten 2.2 MW wind turbinesCrane capacity: 1200 t for handling jackets and tripodsSpeed: >14 knots in calm water at design draughtDynamic positioning: DP-2 @ 2 knots of current and 22 m/s head windJacking conditions: Hs = 1.6 m, Beaufort 6Storm survival conditions: Hs = 5.4 m, Beaufort 12 (36 m/s)Complement: 60 – 70 persons

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Design Development

One of the first designs:

6-legged 155.5 m long and 40.6 m widevessel with 85 m square plate legsand engine room/casing forward

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Owner’s Increased Design Requirements

Relatively early in the design process the design requirements were increased for deeper water and larger wind turbines:

Water depth for jacking: 55 m @ 10 m air gab, 5 m sea bed penetrationCargo deck space: sufficient for twelve 3.6 MW wind turbinesSignificant wave height for jacking: Hs = 2 m (depending on swell)Complement: 110 persons

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Design Development

6-legged 42 m wide vessel with 96 mtruss legs and engine room/casing fwd

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Owner’s Increased Design Requirements

Later in the design process the requirements were further increased for even deeper water and support in the offshore oil & gas sector:

Water depth for jacking: 70 m @ 22 m air gab, 3 m sea bed penetration

Storm survival as a wind turbineinstallation vessel with deck loadof twelve 3.6 MW turbines(vertically stored towers): 100 years storm (70 m/s) on 60 m water depth

@ 17 m air gab

Storm survival as offshore support vessel without deck load of windturbines: 100 years storm (70 m/s) on 70 m water depth

@ 22 m air gab

Significant wave height for jacking: Hs = 2 – 2.5 m (depending on swell)

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Final KEH Design

6-legged 49 m wide vessel with 120 m truss legs and engine room/casing amidships

Principal particulars:

Length over all: 161.0 mBreadth: 49.0 mDepth: 10.4 mDraught, design: 5.5 mDraught, summer max. 6.0 mSpeed, design draught 90% MCR:

calm water: 14.5 kn15 % s.m.: 13.5 kn

Deadweight for jacking: 8,400 tComplement: 110 pers.

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Pacific Orca – As-built

Principal particularsLength oa. excl. helicopter deck: 161.3 mLength oa. incl. helicopter deck: 164.9 mLength bp: 155.6 mBreadth, mld: 49.0 mDepth to main deck, mld: 10.4 mDraught, mld, design: 5.5 mDraught, max. summer: 6.0 mGross tonnage: 14,000 tLightweight incl. 105 m legs: 24,400 tLightweight excl. legs: 18,400 tDeadweight, design draught: 9,900 tDeadweight, max. summer draught: 13,155 tDeadweight, max. for jacking: 8,400 tSpeed, 90% MCR, 15% s.m.: 13.0 knots

Tank capacities:Marine gas oil: 4,285 m3Lube oil: 44 m3Fresh water - potable: 1,533 m3Water ballast: 11,905 m3Treated sewage: 634 m3

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Number of legs

Hull lines and breadth of vessel with 4 or 6 legs

If the width of the critical slot between the crane and the leg in the opposite side shall be maintained, a 4-legged vessel will be approximately 2.8 m wider than a 6-legged, because the spud cans have to be approx. 45 % larger

With wider, but shorter hull and blunter bow a 4-legged vessel will have higher propulsion resistance and less directional stability

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Number of legs

Deck layout and loading flexibility with 4 or 6 legs12 wind turbines or tripods/jackets

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Number of legs

Buoyancy distribution, LCG/LCB and leg loading with 4 or 6 legsIdeal situation: Even trim and equal load on all legs

Only possible with 5 or 6 legs or with 4 legs and a very blunt nose

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Number of legs

Safety against failure of jacking system or sea-bed punch-through

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Number of legs

Safety against sea-bed punch-through in sand overlying clayPhases of the development of the characteristic bearing resistance: a. initial bearing resistance when the widest cross-sectional area of the spudcan is

in contact with the sand surfaceb. maximum bearing resistance in the upper sand layerc. interface bearing resistance when the spudcan penetrates into the underlying

clay

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Number of legs

Number of recorded incidents according to “Guidelines for jack-up rigs with particular reference to foundation integrity – Research report 289 – 2004”

Topic Area  Before 1980  1981‐ 1990  1991‐ 2000  2001‐ 2004  Total 

Spudcan / Pile Interaction  0  8  8  7  23 

Punch‐Through 0  15  13  11  39 

Settlement  1  4  14  10  29 

Sliding 1  3  13  6  23 

Scour 0  3  2  6  11 

Instability of Seafloor  0  3  2  2  7 

Shallow Gas 0  0  4  1  5 

Debris 0  1  1  1  3 

Rack Phase Difference  0  5  1  7  13 

Footprints 0  3  2  10  15 

Layered Soils 1  6  3  3  13 

Cyclic Loading  0  7  20  8  35 

Liquefaction / Pore‐Pressure  1  1  9  2  13 

Fixity 2  17  54  23  96 

Fatigue 0  0  1  4  5 

Risk of Impact with Jacket  0  0  4  4  8 

Case History  0  10  13  10  33 

Unclassified 3  2  13  9  27 

Total No. of Documents  7  44  108  71  230 

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Number of legs

Consequence of punch-through with 4 or 6 legs(Assuming all legs have been pre-loaded by +50 %)

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Number of legs

The choice between 4, 5 or 6 legs

4 legs+ Optimal loading flexibility+ Cheapest - Critical in case of leg failure or punch-through- Difficult to obtain an even load balance between the legs- Higher water resistance and less directional stability because of wider/shorter hull

6 legs+ Optimal safety against leg failure or punch-through+ Optimal load balance between the legs+ Lower resistance and better directional stability because of longer/slimmer hull- Restrictions in loading flexibility- Expensive

5 legs+ Compromise between loading flexibility, safety and load distribution- Restricts the vision from the bridge,- Restricts the boom resting position- Does not provide symmetrical pre-loading of the legs

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Type of Legs

Two types of legs – plate legs (square or tubular) or truss legs

Plate legs+ Cheap and with good shear strength+ Compact design takes little space on deck+ Jacking systems are simple and relatively cheap- Considerably heavier than truss legs- Only suitable for water depths up to approximately 45 m because of the weight

Truss legs+ Suitable for water depths of more than 100 m+ Much lighter than plate legs+ Less wave impact loads- Very expensive- Jacking systems for truss legs are much more expensive than for plate legs

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Spudcans

Types of spudcans

Spudcan with rim skirtVery skid resistant, but very high water resistance because of the recess

Conical spudcanStandard solution, but if the spudcan is not circular the rim will not at all points be in level with the bottom of the ship, which will increase the water resistance

Spudcan with flat bottom and center coneLow water resistance as the rim is in level with the bottom of the ship, but not as self-centering as a conical spudcan

Spudcan designed for easy assemblyEasy assembly in dry dock, but high water resistance because of slots between spudcan and leg well and the design limits the area

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Spudcans

Assembly of leg-well section and leg/spud can

Assembly procedure if the spudcan is too large for the leg including the spudcan to be lowered into the leg-wellKeel blocks need to be relatively high

Assembly procedure if the spudcan is designed so that the assembled leg including the spudcan can be lowered into the leg-well

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Spudcans

Example of spudcan, which is designed so that the assembled leg including the spudcan can be lowered into the leg well

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Jacking System

GustoMSC hydraulic hand-over-hand systems for square plate legs with long lifting cylinders and short holding cylinders – Interrupted motion

Left – System on MPI Resolution with lifting collarsRight – High performance system with lifting yokes

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Jacking System

GustoMSC hydraulic guided-yoke type for tubular plate legsContinuous motion

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Jacking System

Knud E. Hansen A/S compact hydraulic hand-over-hand system with lifting collars for 3-chorded truss legsContinuous motion

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Jacking System

Friede & Goldman electrical rack-and-pinionContinuous motion

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Jacking System

Hydraulic systems:+ Limited wear and tear+ Shock tolerant+ Low price+ Compact design- Long-term maintenance issues because of complicated design with many valves,

hoses, electrical switches and problematic hydraulic seals- Risk of spillage of hydraulic oil

Electrical rack-and-pinion:+ Limited long-term maintenance+ High-speed continuous jacking+ High redundancy

(jacking / lowering is still possible even if one or two units per leg are out of service)

- Expensive- Not very shock tolerant- Must be heavily over-dimensioned (+50%) to deal with wear and tear- Need biodegradable rack greasing oil

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Legs & Jacking System – Final KEH Design

Legs & jacking system

• Number of legs: 6• Length of legs: 120 m (fitted 105 m)• Leg protrusion below BL of ship: 80 m @ 105 m legs / 95 m @ 120 m legs• Number of chords per leg: 3• Chord distance: 9.7 m• Chord type: Split-pipe, 6” rack• Jacking system maker/type: BLM electrical rack-and-pinion• Jacking units: Double-pinion D110 V units• Jacking unit motors: 690 V, 70/90 kW, 1800/3600 RPM• Number of jacking units per leg: 3 x 6• Jacking speed, raising/lowering legs: 2.4 m/min• Jacking speed, raising/lowering hull: 1.2 m/min• Rated normal jacking capacity per leg: 4,500 t• Pre-loading capacity per leg: 6,750 t (+50%)• Max. soil penetration capacity per leg: 8,820 t• Static holding capacity per leg: 10,650 t• Rack chock system for static holding: No

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Legs & Jacking System – Final KEH Design

Legs & jacking system – Fatigue life / wear and tear

Jacking system and leg racks is over-dimensioned by 50 % to reach a theoretical fatigue life, which is defined as at least 5000 cycles (e.g. 200 cycles per year during 25 years) of each of the following operations:

Leg lowering: 25 m Leg load: 750 tLeg pre-loading / soil penetration: 8 m Leg load: 6,600 t

Hull lifting: 15 m Leg load: 3,700 t (2,500 cycles)Hull lowering: 15 m Leg load: 3,700 t (2,500 cycles)

Hull lifting: 15 m Leg load: 4,400 t (2,500 cycles)Hull lowering: 15 m Leg load: 4,400 t (2,500 cycles)

Leg soil extraction: 8 m Leg load: 6,600 tLeg lifting: 25 m Leg load: 750 t

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Leg Configuration – Final KEH Design

Longitudinal position and turn of legs

Aft• optimization of width of slot between crane and jacking frame• optimization of lines in way of spudcans

Midship • optimization of horizontal operational sector of aux crane• Longitudinal position optimized for even load balance between legs

Forward• retracted for refined lines in shoulder region and reduced buoyancy forward • optimization of space for MOB and life boats• optimization of lines in way of spud cans

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Spudcans – Final KEH Design

Design of spudcans optimized for: • adapting to hull lines and minimum water resistance

(necessary because of the required service speed)• maximum area (125 m2)• minimal bending moment in legs considering the large area

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Legs & Jacking System – Pacific Orca

120 m truss legs with rack-and-pinion jacking system and 6 BLM D110 V (double-pinion) units per leg chord – Identical to final KEH design

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Spudcans – Pacific Orca

Spudcans are designed so that the legs can be lowered into the leg wells(jacking frames and upper leg guides not fitted during this procedure)

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Spudcans – Pacific Orca

Spudcans: Conical, buoyantArea: 95.4 m2

Optimal height of legs for minimum water resistance is 500 mm below bottom of ship

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Crane Configuration

Initial KEH proposal for work-around-leg cranes for truss legsMain crane: Asymmetrical, 1200 t, rope luffingAux crane: Asymmetrical, 300 t, hydraulic luffing with telescopic boom, which

can cover most of the main deck and work below the main crane while this is resting in the boom rest cradle

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Crane Configuration

KEH design with Huisman cranesMain crane: 1200 tAux crane: 300 t

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Crane Configuration – Final KEH Design

Main crane: NOV work-around-leg w. 2 x 600 t main hoists for 1200 t in tandemAux crane: Huisman 300 t rope luffing, mounted on cantilever on jacking frame

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Crane Configuration – Pacific Orca

Main crane

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Crane Configuration – Pacific Orca

Main craneMake: NOV AmclydeType: Rope luffing, “work-around-leg”

Main hoists: 2 x 600 t side by side for 1200 t in tandemLoad: 1200 t @ (14) 18 - 31 m

600 t @ 50 mMax load radius: 91 m

Aux hoist: 500 t @ 20 – 60 mMax load radius: 107 m

Whip hoist: 50 t @ 23 – 113 m, approved for man riding

Tuggers: 7 x 5 t SWL

Max. wind speed: 20 m/s

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Crane Configuration – Pacific Orca

Auxiliary craneMake: NOV AmclydeType: HydraulicMain hoist: 35 t @ 6.5 to 35 mAux hoist: 25 t @ 6.5 to 40 m

approved for man-riding

Knuckle-boom craneMake: NOV AmclydeType: Hydraulic with

telescopic jibHoist: 2 t @ 25 m, 4 t @ 14 mMan-riding radius: 30 m by operating

telescopic jib

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Stern Thrusters

ABB’s gearless Compact Azipod rightSchottel geared azimuth thruster below

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Stern Thrusters

Voith Schneider

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Stern Thrusters

Geared azimuth thrusters+ Cheap and well proven solution- Sensitive to ventilation shocks because of the gears- Must be turned 180 degrees to reverse thrust

Gearless Compact Azipods+ Very robust and insensitive to ventilation shocks because of the lack of gears+ Simple installation+ High efficiency because of permanent magnet motor and no gear losses- Not as well proven as standard geared azimuth thrusters- More expensive than geared azimuth thrusters - Must be turned 180 degrees to reverse thrust

Voith Schneider thrusters+ Very quick steering reaction – excellent for DP and course keeping+ Do not have to be turned 180 degrees to reverse thrust+ Slow turning with low vibrations+ Insensitive to ventilation shocks because of the slow turning motion- Very expensive- Very heavy- Not suitable for higher speeds

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Bow Thrusters

Left: Schottel tunnel thrusterMiddle: Shottel & Rolls Royce retractable azimuth thrustersRight: Brunvoll retractable combi azimuth/tunnel thruster

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Bow Thrusters

Standard tunnel thrusters+ Cheap and well proven solution+ Works on shallow water- Low efficiency at speeds above 4 knots

Retractable azimuth thrusters+ Much more efficient on deep water than tunnel thrusters- Not suitable on shallow water where they cannot be lowered

Retractable combi azimuth/tunnel thrusters+ Much more efficient on deep water than tunnel thrusters+ Works both as tunnel thrusters and retractable azimuth thrusters- Nozzle not quite as efficient as on normal retractable thrusters- More expensive than normal retractable thrusters

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Thruster Configuration – Final KEH Design

Thruster configurationStern thrusters:Under consideration: 4 x 3.4 MW Voith Schneider (36R6/265-2)Final choice: 4 x 3.4 MW ABB Compact AzipodsReason for decision: Price and weight

Bow thrusters:Under consideration: 2 x 2.2 MW Brunvoll combi + 1 x 2.2 MW tunnelFinal choice: 2 x 2.2 MW retractable + 2 x 2.2 MW tunnelReason for decision: Better power balance between stern and bow for DP

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Thruster Configuration – Final KEH Design

Dynamic positioningUpper view: all thrusters operatingLower view: one thruster lost

Note that in both cases DP can be performed by adjusting the power balance without turning the thrusters

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Thruster Configuration – Pacific Orca

Thruster ConfigurationBow tunnel thrusters: 2 x Brunvoll FU100LTC2750, 2.2 MWBow retractable azimuth thrusters: 2 x Brunvoll AR100LNA2600, 2.2 MWStern azimuth thrusters: 4 x ABB Compact Azipod, 3.4 MW

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Cargo Deck – Final KEH Design

Structural design of cargo deck

Grid system of transverse girders with a spacing of 1.4 m and longitudinal girders or reinforced longitudinals (HP 300x11) also with a spacing of 1.4 m creates a grid system of strong points in a mesh of 1.4 x 1.4 m

Max. load in strong points: 250 t down / 200 t up (pull) @ 4.2 m transverse distance between two loads on same transverse girder

Uniformly distributed load:Aft and amidships: 20 t/m2Forward: 15 t/m2

Wear & tear allowance:Aft & amidships: 3 mmForward: 2 mm

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Cargo Deck – Final KEH Design

Structural design of cargo deck

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Cargo Deck – Pacific Orca

Cargo deck area: 4300 m2Grid system of strong points aft and amidships (mesh 1.4 x 1.4 m)Max. load in strong points:

Downwards: 250 tPull: 200 t

Uniformly distributed load: 15 t/m2Wear & tear allowance:

Aft & amidships: 3 mmForward: 1 mm

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Engine Arrangement – Final KEH Design

Engine room arrangement

Under consideration: Engine room and casing forward for optimal deck space for cargo in way of the midship legs

Final choice: Engine room and casing amidships

Reason for decision: Wider stern-facing bridge and less noise and vibrations in the accommodation

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Engine Arrangement – Final KEH Design

Engine room arrangement

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Engine Arrangement – Pacific Orca

Engine arrangement

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Engine Arrangement – Pacific Orca

Diesel generatorsMake and type: 8 x MAN 9L27/38, 750 RPMType of fuel: Marine gas oilRated electrical power: 3024 kW

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Engine Cooling while Jacked-up

Engine cooling:• Sea water cooling by

submersible pumps• Air cooling

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Engine Cooling while Jacked-upPacific Orca

Sea water pumps arranged in SB just aft of the forward legPumps will have to be lowered over the side whenever the vessel is jacked

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Accommodation – Final KEH Design

Accommodation block

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Accommodation – Pacific Orca

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Accommodation – Pacific Orca

AccommodationNumber of single cabins: 111, all with bath room

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Helicopter Deck – Pacific Orca

Helicopter deckD-diameter: 22 m, Load-bearing capacity: 12.8 t (medium size helicopters)

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Questions?

?Thanks for your attention

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