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Theater Access Workshop

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1 Theater Access Workshop
Joint Seabased Theater Access Workshop Duck, NC 8-10 February 2005 Deep Water Stable Craneship Mark Selfridge UK MOD Exchange Naval Architect NSWC-CD/CISD Paper previously presented at ASNE Joint Seabasing Conference January 2005

2 ACKNOWLEGEMENTS ONR : RADM J Cohen
CISD Seabasing Innovation Cell : original members Feb-May 03 Dr Colen Kennell : original idea Michael Gilbertson : spar sizing and initial design Jerry Sikora : x-Code 6500, preliminary spar structural design Tim Smith : Code 5500, Seakeeping Dan Jacobs : catamaran design ONR NREIP students : Gena Johnson, Jamie Graham and Paul Morriseau : hinge and connector design, animation UK MOD & DESG : Exchange Officer & Graduates FAU OE Dept : 1:15 scale ‘Demonstrator’

3 AGENDA Current practice Sea Basing challenges Spar technology
Deep Water Stable Craneship Design development Performance assessment Alternative uses FLIPSHIP-II FAU 1:15 scale “Demonstrator”

4 CURRENT MATERIEL TRANSFER

5 Current at-sea container transfer… Note: Size of the craneship
Size of cranes Seastate (benign)

6 (Open Ocean N Atlantic) Significant Wave Height
SEA BASING CHALLENGES MATERIEL At-sea transfer of TEUs through seastate 4 Quantities / rates / types / packaging / selectivity Interface with commercial / allied shipping Weight : ~15 tons Size : 20’ x 8.5’ x 8’ Seastate (Open Ocean N Atlantic) Significant Wave Height Sustained Wind Speed Modal Wave Period 2 m kts secs 4 m kts secs current limit goal TEU : Twenty-foot Tonnage Equivalent Unit (i.e. Shipping Containers)

7 (just for the shore based MEB)
MARINE EXPEDITIONARY BRIGADE (MEB) - DAILY DEMANDS MEB ~13,000 troops 6,800 troops ashore / 6,200 afloat Materiel ST/day WATER 190 CARGO FUEL 225 DRY STORES - Food 15 - Ammunition 33 - Other1 27 Sub-total (liquids) 415 ST/day Sub-total (dry stores) 75 ST/day TOTAL 490 ST/day1 Materiel demands for troops ashore ~ 30 to 70 TEU / day (just for the shore based MEB) 1. May increase to 1,000 ST/day depending on OP-TEMPO

8 Significant offshore use / experience Superior seakeeping
SPAR TECHNOLOGY Significant offshore use / experience Superior seakeeping Little or no Military experience Lack of awareness / particularly performance Can solve at-sea container transfer for military Speed x 3 FLIPSHIP ‘flipping’

9 Developed at NSWCCD / CISD Feb-May 2003
DWSC Concept Overview Spar mode Developed at NSWCCD / CISD Feb-May 2003 Container transfer capability Detachable spar to increase utility in littorals Pendulation minimized & low motions 4 alternative seabasing uses (causeway, breakwater, DWSC, harbor craneship) Surface mode

10  size hinge & connectors
Design Spiral Resistance & powering (hullborne & sparborne)  hence speed Identified COTS crane Identified propulsion requirements Loadcases  size hinge & connectors Stability assessment in spar mode Structural design of Spar  structural weight Re-sized original Spar Stability assessment of craneship Selected machinery plant Updated resistance & powering predictions  revised speeds Synthesized catamaran craneship design Spar shaping bow & upper surface Developed alternative configurations / uses Determined spar operability worldwide (depth contours) Produced 3D models, arrangements & animations Seakeeping

11 Animation

12 Powering - surfaced Speed ~20 knots
5,000 10,000 15,000 20,000 25,000 10 20 30 40 50 Speed (knots) Effective Power (kW) Drag = frictional + residuary + correlation allowance Trimaran Spar Craneship Length (m) L/1/ SH /  DWSC Model test data for the High Speed Sealift Trimaran scaled to 2,200te 1 kW = hp or 1 hp = kW L/1/3 : Slenderness Ratio Speed ~20 knots Surface mode ie no crane usage, just hotel load (300kW) 4MW installed power Minus 0.3MW hotel load Equals 3.7MW power available for propulsion Assumed PC of 0.6 Then Effective Power = PC x Available Installed Power Pe = 0.6 x 3.7 = 2.22MW But given uncertainty in PC, we have applied a band. DWSC Total Displacement ~2,200te Craneship = 650te Spar = 1,220te Casing = 100te (111m x 8.5m x 12mm x 7.85te/m3 = 89te rounded to 100te) Piping for ballast pumps = 50te Margin on weight = 80te Fuel = 100te (typically would provide ~2,000nm range) TOTAL = 2,200te

13 Powering - vertical DWSC Speed ~4 knots Effective Power (kW)
1,000 2,000 3,000 4,000 1 2 3 4 5 6 Speed (knots) Effective Power (kW) CD=0.41 7.4m 105m 2m 6m 8.5m DWSC 1 hp = kW CD : Drag Co-efficient Assumed Propulsive Coefficient, PC = 0.5 Speed ~4 knots CRANE USE + HOTEL LOAD HOTEL LOAD ONLY Spar mode, No crane usage, just hotel load (300kW) 4MW installed power Minus 0.3MW hotel load Equals 3.7MW power available for propulsion Assumed PC of 0.5 Then Effective Power = PC x Available Installed Power Pe = 0.5 x 3.7 = 1.85MW (NO CRANE USE) Spar mode, with crane usage (235kW) & hotel load (300kW) Minus 0.3MW hotel load, Minus 0.235MW crane use Equals 3.465MW power available for propulsion Pe = 0.5 x = 1.73MW (INC CRANE USE)

14 Catamaran Design Resistance & Powering predictions indicate
4MW of Installed Power would provide; ~20kts hullborne ~3kts sparborne RV Triton’s Integrated Propulsion Plant provides; 4MW of installed power Propulsion & electrical machinery weights Integrated Propulsion System (IPS) Prime movers drive generators that produce electricity for propulsion motors and ship services and combat systems.

15 COTS Crane Hydralift Offshore Knuckle Boom Crane
Weight (with pedestal) : 65.5 tonnes Power requirement : 235 kW Folded Extended (max) 30m (98ft) 25m (82ft) DWSC sized for 15te 30m (98ft) & max heel +/-2.5 degrees The crane requirements were; Max Reach of 30m (98.4ft) Lift 15te at max reach Be as light as possible REACH A 30m reach allows for; half beam of catamaran (15.75m/2 = 7.875m) 5m offset between catamaran and supply ship ability to reach centreline of Panamax Containership at 32.3m (106ft) So, /2 = 29m (95.2ft) LOAD The 15te load was derived from 50% of the max load of a 20ft container. Since this figure was assumed, a load of 20te has been postulated. This is well within the capability of this crane. It is worth noting that the DWSC is scaleable.

16 Methodology - used existing vessels to de-risk catamaran sizing
MV Duplus USNS Hayes USNS Hayes (T-AGOR16) - 3,600te Steel Catamaran Oceanographic research / towed array ‘tug’ Geometric scaling only RV Triton - 1,116te Steel Trimaran Research vessel Weight scaling (SWBS groups 2-8) MV Duplus1 - 1,200te Steel Swath North Sea oil rig supply tender with central drilling rig Volumetric scaling for structural weight (SWBS group 1) MV/RV - Merchant Vessel / Research Vessel SWBS - Ship Weight Breakdown Structure USNS - United States Naval Ship SWATH - Small Waterplane Area Twin Hull MWATH - Medium Waterplane Area Twin Hull 1 MV Duplus later renamed MV Twindrill (modified to a MWATH : waterplane increased to improve stability during crane use) Methodology - used existing vessels to de-risk catamaran sizing RV Triton HAYES - used for geometric scaling only ie the overall size and dimensions TRITON - used for weight scaling of SWBS groups 2-8 DUPLUS - used for weight scaling of SWBS group 1 (structural weight) (speak to Dan about Rushcutter and exactly what he did here)

17 Weight Summary 1 Group 1 Hull - Steel construction
Units in metric tonnes SWBS - Ship Weight Breakdown Structure 1 Group 1 Hull - Steel construction 2 Group 6 Outfit & Furnishings - Crew (3 officers + 8 rates) 3 Group 7 Armament - None fitted 4 Group 9 Margins - Assumed prorated over Groups 1-8

18 Crew Quarters Power Conversion Intake/Uptake Laundry Rec. Room
Mess/Galley Access to Deck Officers’ Quarters Exercise Area Stores Generators Motors Gears Rec. Space Gearbox Ramp Driving Lane CRANE positioned amidships on CL to minimize trim/heel seat for spar provides ideal foundation for crane full 360 operability UPPER DECK LAYOUT ramp & driving lane for causeway operations deckhouse offset to facilitate ‘traffic’ lane INTERNAL ARRANGEMENT Crew - 3 officers in single berths + 8 rates in twin berths Main propulsion machinery in sidehulls (centered about amidships) Power conversion in cross deck FUEL 50te of fuel HULL Steel, cross deck aft braced rather than continuous deck ANCHORING Aft (various positions - under cross deck, port quarter deck)

19 Principal Characteristics
Dimension (m) (ft) Length Overall (LOA) 38.70 127.0 Beam (B) 15.75 71.7 Draft (T) 3.13 10.3 Side hull Beam (BSH) 4.00 13.1 Side hull separation 7.75 25.4 Wet Deck Clearance 2.87 9.4 Depth (D) 9.67 31.7 GMt 10.70 35.1 Air Draught (TAIR) 14.87 48.8 Displacement 650 te BEAM Overall beam of catamaran is driven by the diameter at the top of the spar. At 6m, it dictates the sidehull separation to be at least 7m. Stability, is another important consideration in terms of the beam of the ship, particularly stability during crane operations. The aim was to minimize the heel during a 15te lift at 30m to less than 2.5 degrees. This was achieved by providing adequate sidehull beam and sufficient sidehull separation. The resulting maximum beam was 15.75m with a 7.75m sidehull separation. WET DECK CLEARANCE (WDC) A US Swath TAGOS 19 is designed to operate at all headings while towing arrays at the top end of SS6 (H1/3 = 6m / 19.7ft) and has a wet deck clearances of 13ft bow, 9ft amidships and 11ft stern. (3.96/2.74/3.35m) The wet deck clearance for the craneship is much smaller (2.87m) given; Spar provides protection (when connected) No requirement to remain operational in higher seastates A high WDC aggravates structural weight & total displacement A compromise was achieved between structural weight, slamming and the ability to physically fit the spar under the wet deck when in surface mode.

20 1 Heel angle during a 15te lift at 30m limited to +/-2.5 degrees
SPAR - Primary Design Drivers; Top weight  Catamaran weight Crane lift requirements  heel angle1 Length/Diameter (L/D)  structural strength Pressure head  structural weight Other considerations; Sidehull separation Wet deck clearance / Draft of SPAR on surface Low waterplane area (for seakeeping) Resistance & powering Shape of bow / Upper surface (causeway) Integration of thrusters Interface with Catamaran (Hinge & Connectors) 1 Heel angle during a 15te lift at 30m limited to +/-2.5 degrees TOP WEIGHT The overall weight of the catamaran is significant not in terms of the ballasting/de-ballasting requirement (to lift it out of the water) but because it is top weight that has to be countered by a lot of seawater ballast which drives up the size of the spar. CRANE LIFT REQUIREMENTS The lift and reach requirements for the crane will result in a certain angle of heel for a given GM. The heel angle can be minimized by providing adequate GM. GM is determined by the seawater ballast and the size and shape of the spar. L/D High L/D ratios result in large bending stresses in the keel and upper deck on slender structures in a seaway. Whipping is probably more significant and generally results in L/D ratios of 15 maximum. The US Navy have built and operated ships with higher L/D ratios.see colen for DDG51 FFG7 It should be noted, the DWSC could accept a higher L/D than say a major surface combatant given that the DWSC does not have to maintain speed and /or heading in all sea-states and is not expected to withstand shock loadings. Its structural design is such that the pressure head is likely to call for heavy gauge steel plating. Structural weight does not need to be minimized on the SPAR since the center of gravity of the spar structure is below the CoG for the rest of the platform, it actually helps with stability and minimizes the amount of seawater ballast required and hence the size of the spar. PRESSURE HEAD The pressure head at the bottom of the spar is (118m draft); 1.0252x1000 x 9.81 x = MN/m2 ~ 12bar 1.0252x1000 x 9.81 x 59 = MN/m2 ~ 6bar Hence, the need to design submarine type structures in the areas where hard tank structure are required. The bottom 1/3 rd does not need to be ‘hard’ as the pressure differential will always be very low and so ship like structure is all that is required (as a result of pressure) at the bottom of the spar. A small hard tank may be provided at the bottom of the spar to assist with the transition to the surface. The middle 1/3rd will see high differential pressures and so overall collapse and interframe collapse are of concern – just as with submarines. The upper third is designed to provide hard tank structural requirements.

21 Revised Baseline Baseline Dimension Revised 127.0 Length (m) 129.6
111.0 Draft (m) 118.0 11.9 Lower diameter (m) 8.5 6.9 Upper diameter (m) 6.0 16.0 Freeboard1 (m) 11.6 2,513 Structural weight (te) 1,220 8,000 Seawater ballast (te) 4,745 50.9 KB (m) 57.9 49.2 KG (m) 56.3 1.76 GMT (m) 1.57 500 Catamaran weight (te) 650 11,013 Total Displacement (te) 6,615 Revised Baseline Steps in developing the spar concept; Reduce clearance from 16m to 11.6m  shorter spar Maintain original length  reduce diameter Re-evaluated spar structural weight  became lighter Refined estimate of Catamaran  te The combination of the lighter spar (3.) and the heavier catamaran (4.) resulted in a slight increase in overall length. Note 1 : both spars were designed to provide sufficient GM so that the maximum heel angle under a 15te lift at 30m would be <= 2.5degrees. The reduced freeboard, lighter spar structural weight and reduced ballast resulted in a 40% reduction in total displacement (11,013 to 6,615te). Note 2 : the 11.6m freeboard to the wet deck still allows for 5.6m from the water to the keels of the catamaran sidehulls (when sparborne). The significant waveheight in SS6 is 4-6m, so 5.6m is upper SS6. Even then it is the top of the wave where there is little energy. TAGOS 19 has maximum 3.96m wet deck clearance for continuous ops in SS6! Seawater Ballast Draft (horizontal) = 2.4m with 400te seawater ballast 1 Freeboard here is the vertical distance from the waterline (in spar mode) to the wet deck of the catamaran. KB : Vertical center of Buoyancy, KG : Vertical center of Gravity GMT is the Transverse Metacentric Height and is a measure of stability. Both Spars were designed for a maximum heel of 2.5 degrees under a 15te lift at 30m whilst spar-borne.

22 DWSC Seakeeping (Seastate 4)
Initial Spar (ROLL) Revised Spar (ROLL) SEASTATE 4 Max heave amplitude ~ 0.11m Max roll/pitch angle +/- 0.80 Max heel due to 15mt +/- 2.50 Max roll angle of 0.8 degrees (DUE TO SEASTATE) Even allowing for heel of +/- 2.5 degrees (DUE TO STATIC HEEL DURING LIFT) Then; = ~3.3 degrees in SS4 ! So well within the 5 degree limit of the crane in SS4 ! Hence, MAX HEEL ~3.30 in SS4 with a 15mt

23 SPAR Seakeeping (Seastate 6)
Revised Spar (ROLL) SPAR Seakeeping (Seastate 6) SEASTATE 6 Max heave amplitude ~ 0.90m Max roll/pitch angle +/- 2.90 Max heel due to 15mt +/- 2.50 Max roll angle of 2.9 degrees (DUE TO SEASTATE) Even allowing for heel of +/- 2.5 degrees (DUE TO STATIC HEEL DURING LIFT) Then; = ~5.4 degrees in SS6 ! So ‘around’ the 5 degree limit of the crane in SS6 ! RMS = sqrt.mo SIGNIFICANT = 2xRMS MAXIMUM = 4.45xRMS (for N = 10,000 cycles) Hence, MAX HEEL ~5.40 in SS6 with a 15mt

24 Comparison of Natural Periods
Comparison of initial and revised spar; Smaller waterplane area of revised spar should have caused an increase in heave period, but the reduction in mass lowered the natural period. The increase in length of the revised spar increased the mass moments of inertia, increasing the natural roll and pitch periods. Displacement Summary (mt) LCU ,087 LMSR 63,978 DWSC (initial) 11,013 DWSC (revised) 6,615

25 Connector Design - Loadcases
SPAR-BORNE Catamaran athwartships bending L Torsional loading due to crane List / heel angle loading H Mooring forces Heave forces LCG / TCG variation1 Thruster torque Wind loading Rogue wave - stern slam Rogue wave - immersion SURFACE-BORNE Wet deck stern-slam H Catamaran side-slam Quartering sea loads M Roll bending Collision / grounding Deep ballast tension L Spar side-slam Wave-induced bending Propeller / thruster torque Yaw Maneuvering L / M / H : Low / Medium / High 1 LCG /TCG : Longitudinal and Transverse Centers of Gravity

26 Connector Design - limiting loadcases
MODE Loadcase Force (ton) Area req’d (ft2) Surface Collision (>10 sec) 611 [-x] 0.43 Catamaran side-slam 5,485 [+y] 3.69 Spar-borne Rogue wave : stern-slam 3,619 [+z] 2.95 Top-connectors (Surface mode) End-connectors (Spar-borne) Hinge/lug Spar-borne End-connectors Area available 28m2 Area required 12m2 (43%) Factor of Safety of 4 Assumed 7 Radius 0.73m Surface mode Top-connectors Area available 45m2 Area required 15m2 (33%) Factor of Safety of 4 Assumed 12 Radius 0.62m z x y Spar Profile

27 SPAR Operability : 200m depth contour
Arabian Sea Bangladesh ~150nm India Iran Iraq Arabian Sea Saudi Arabia Yemen Ethiopia Oman Pakistan Afghanistan Persian Gulf Red Sea Bangladesh Thailand Burma Shallow Water < 200m Deep Water >= 200m Source : National Imagery & Mapping Agency (NIMA) - World Vector Shoreline Plus (WVSPLUS®)

28 Spar Craneship : Alternative Uses
Harbor Craneship ‘Shallower’ Water Bottom Sitting Offload Facility shown in transit (Seabase closer to shore) Spar-Causeway Deep Water Stable Craneship (Seabase offshore) Rapidly Deployable Breakwater

29 Bottom-sitting Offload Facility
shorter ‘stumpy’ spars 3 Modules; Stowage Craneship Service Deep Water Stable Craneship alternative uses Deliverables:

30 Surface mode Spar mode Deep Water Stable Craneship Concept
Spar and Catamaran craneship form trimaran Spar is detachable - providing useful craneship Self-propelled on surface & in spar mode ~20kts surfaced, ~4kts in spar mode Inspired by FLIPSHIP Surface mode Spar mode Key Design Drivers Connectors Hinge Speed on surface and in spar mode Control during ballasting Stability Seakeeping Draft / depth of water Military Benefit Extends crane transfer through SS5 Pendulation minimized (>2minute roll period) Provides container transfer capability Reduces fleet wide craneage requirements Increases interoperability with commercial ships

31 Spar Technology has superior seakeeping
De-risking to date Revised/refined design of; Spar Catamaran Craneship Sizing of hinge and connectors Shaping for powering and other uses Visit to FLIPSHIP to ‘FLIP’ Worldwide Operability Stability & Seakeeping Status Identified Design Drivers Quantified performance in a credible seabased scenario Further Work FAU Design, Build & Test 1:15 scale demonstrator De-risk Key Design Drivers Deliverables: We aim to demonstrate…. Spar Technology has superior seakeeping Alternatives; Re-fuelling Lily-pad Special Forces Operating Base FLIP II (Craneship Critical Technology Demonstration)

32 FAU Ocean Engineering Dept
Design, Build & Test a 1:15 scale Demonstrator No crane Unmanned (for safety) Self-deploying Working ballast system Partial funding from ONR Project Advice from CISD Critical Design Review : complete 01-Dec-04 Construction started end January At-sea testing mid-April 2005 4 Teams (Catamaran, Spar Structure, Ballast and Control Systems)

33 QUESTIONS


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