New Vessel Fuel Efficient Design and Construction Considerations Medium and Long-Term Options By Dag Friis Christian Knapp Bob McGrath Ocean Engineering Research Centre MUN Engineering
Overview : Introduction Design Cycle Statement of Requirements Design Operational Considerations Vessel Design Considerations Base Efficiency Considerations in Design Ongoing Simulations & Testing What to Look for going forward Conclusions
Introduction: The changes in the fishery since the moratorium in 92 have significantly changed the demands on fishing vessels and crew One has a need for the ability to fish multiple species & Areas This has put undue pressure on vessel design without a corresponding change in vessel size restrictions Harvesters are Steaming farther from Shore and thus subject to significantly increased sea states The time for Steaming to and from grounds has increased This means that there is a need for Naval Architectural & Engineering expertise in order to ensure that Vessels are designed to be: Safe, stable and economically advantageous platforms for executing the fishery of today and the future This should lead to a return to more reasonable & proportional vessel dimensions.
Statement of Requirements This is what the Naval Architect/Designer uses as a framework for the design of your boat It should state the performance objectives that the design should achieve in order to make the boat a viable business proposition as well as a safe workplace for you and your crew Preliminary Economic Considerations
Basic Design Cycle Statement of Requirements: Hold Space Quota Requirements Principal Dimensions (Parametric Study) Expected Lifetime Operational Considerations Performance Predictions Seakeeping Seaway Powering Simulations/Modelling/Tank Testing Noise/Vibration Issues Fish & Crew Disruption Preliminary Design Calculations Resistance Powering Weight Estimate Propellers Cost Estimate Economic Analysis Life Cycle Payback Period/Rates of Return General Arrangement Preliminary Shape Outfit Auxiliary Power Gear
WEATHER CONSIDERATIONS: NEWFOUNDLAND AND LABRADOR HAS A LARGE AND DIVERSE COASTLINE WITH SIGNIFICANT VARIATION IN OFFSHORE CONDITIONS: 1. Where do you fish 2. What do you fish 3. What Gear is Required 4. How long do you intend to keep fishing
Overview of Considerations: Vessel Handling and other characteristics Directional Stability Noise and Vibration Considerations Moment induced Interrupts (MII s) Fish Harvesting is a business Efficiency in harvesting Energy Efficiency Decisions Based on Return on Investment Catch handling/stowage methods, for example: On Deck Chill Tank Boxing (with desired capacity) RSW (with desired capacity) DFO vessel size restriction applicable criterion
Design Considerations: **THE LARGER THE WAVE SYSTEMS AND THE MORE WATER PULLED IN THE WAKE THE MORE FUEL SEND UP THE STACK FOR LITTLE INCREASE IN PERFORMANCE** 8
EFFECT OF BOW TYPE ON RESULTANT WAVE SYSTEM Standard Bow ~ 15 Knots Full Scale Equivalent (L/B = 3) Bulb A ~15 Knots Full Scale Equivalent (L/B = 3)
Case Studies: 34 11, 44 11, 64 11 Energy Efficiency Simulation: Vessel Information: 65 Footer L/B = 2.822 45 Footer L/B = 2.028 35 Footer L/B = 2.26 Overall Vessel length 64'11" 44'11" 34'11" Design Water Line Length 63'6" 42 7" 33'11" Design Displacement Cu. #: 17536 32.80 LT? Design Draught 11' 2.27 M 4' Beam at Design Draught 22'6" 21' 15' Depth to keel 12' 9'? 1/2 Angle of Entry of Bow?? 40 degrees Engine Power 720 HP 440 HP 250 HP Gearing Ratio 5.07:1 (5;1) 3.00:1 2.79:1 Propeller type Hawbolt 4 Wing 3 Wing Brass Fixed 25" x 27" Propeller Diameter 66" 44" 25" Pitch 52? 27" Blade Area Ratio 76" (5" Clearance)?? Operating RPM: Steaming 1500 RPM 1400-1450 RPM 1600 RPM Operating RPM: Fishing/Towing 1250 RPM (Max. 1800) 600-700 RPM 800 RPM (Max. 2600) Controllable Pitch prop? N/A N/A N/A
Case Studies: Simulations & Analysis Appendage Drag: Best and Worst Case Hull Surface Fouling: Drag Clean vs. Fouled Effect of ½ Angle of Entry : varied from 110% of As-Built to 70% As-Built Change in Displacement with bow ½ Angle All other parameters constant Effect of Immersed Transom: Varied as 100% of Midship Draught to 10% of Midship Draught (A box to a Wedge!) Change in Displacement with transom draught All other Parameters Constant Estimated Power Requirements in a Seaway: Calm to SS6 Estimated Powerw in a Seaway for Ideal Hull: 10% of Midship Draught Transom Immersion 70% of As-Built ½ Angle Overall increase in length by 5 ft or 10ft for the 65 Lengthened Skeg to achieve greater propeller clearance Change in Displacement with length increase Propeller Simulations: (Overall Propulsive & Required Engine RPM & Power) As-Built Efficiency Optimised Propeller, As-Built Hull, Efficiency: Idealised Hull and Propeller 11
Generate Test Series & Design Envelope Three bulbous bows designed & Tested in: Seakeeping (Zero speed) Resistance Self-Propulsion Vessel Lengths Tested to date: 45 65 110 100 90 12
Percentage Difference [%] Powering Breakdown 35 : Estimated Effect of Hull Fouling, Appendage, Immersed Transom and Half Angle on Service Power with As Built (L/B ~ 2.33) 80.00% 60.00% 40.00% Appendage Drag Fouling Drag 33% Increase in Transom Draught 66.7% Increase in Transom Draught 100% Increase in Transom Draught 33% Reduction in Transom Draught 66.7% Reduction in Transom Draught 10% Increase in Half Angle 10% Reduction in Half Angle 20.00% 0.00% 2 3 4 5 6 7 8-20.00% -40.00% Speed [knts]
Simulated Idealised Vessel: Lengthened Bow Finer & Gradual Shape Lengthened Bow Finer & Gradual Shape Reduced Shoulder - Reduced Flow Separation
Considerations of Energy Efficiency In Hull Form Design : Low L/B ratios Requires large amount of energy to accelerate water out and around the hull High likelihood of flow separation in the aft body and resulting energy absorbed in eddy making Blunt Bow Large Angle of Entrance High pressure over a large area at the bow creating large bow wave Possibly creating a second bow wave system at the shoulder 15
EFFECT OF BOW & L/B RATIO ON RESULTANT WAVE SYSTEM L/B = 4.074 (Bulb A) L/B =2.407 (Standard Bow) L/B 2.4
Critical Wave Height in metres The Influence of Vessel Length on Seakeeping: Investigated Seakeeping performance and Influence on the number of days available for fishing. Seakeeping done on all bows for 90 at ahead, ahead quartering, beam and stern seas. One Test Included a basically modelled Vessel anti-roll Critical Wave tank Length Height Threshold, MII/minute 6 5 4 3 2 Critical Wave Height Critical Wave Height (m) Poly. (Critical Wave Height (m)) y = -0.0002x 2 + 0.059x - 0.0718 R 2 = 0.983 65 feet 3.0 m 0.955 1 85 feet 3.75 m 1.06 90 feet 4.0 m 0.992 110 feet 4.25 m 0.856 150 feet 5.0 m 1.08 0 0 20 40 60 80 100 120 140 16 Vessel length in feet 17
fuel consumption rate relative to 65' vessel The influence of Vessel Length on Fuel Consumption: Investigated Energy Efficiency as a function of vessel length 120.00% 100.00% % fuel rate per lb Estimated the Fuel Consumption per Pound of Catch over a variety of Lengths 80.00% 60.00% 40.00% % 20.00% 0.00% 0 20 40 60 80 100 120 140 160 Vessel length in ft
Influence of Vessel Beam on Fuel Consumption: 10 knots Pservice Difference Difference Relative to 27 B/L Beam (ft) Pservice (kw) % Relative to 27' 0.278 25 486.46-9.02% 0.300 27 534.68 0.00% 0.311 28 557.52 4.27% 0.322 29 581.41 8.74% 0.333 30 605.79 13.30% 0.356 32 654.43 22.40% 0.378 34 702.95 31.47% 0.400 36 752.50 40.74% 0.422 38 802.34 50.06% 0.444 40 852.87 59.51% B/L Beam L/24hrs litres/24hrs 0.278 25 600.00-48.0000 0.300 27 648.00 0.0000 0.311 28 672.00 24.0000 0.322 29 696.00 48.0000 0.333 30 720.00 72.0000 0.356 32 768.00 120.0000 0.378 34 816.00 168.0000 0.400 36 864.00 216.0000 0.422 38 912.00 264.0000 0.444 40 960.00 312.0000
The Effect of Stern Shape and Immersed Transom on Design: Submerged Transom Creates a very low pressure at the stern resulting in a large mass of water being dragged along with the boat Poor flow of water to the propeller Resulting from flow separation due to the high rate of change in stern lines Further aggravated by the presence of a large amount of submerged transom area NO Stern Rise = High Transom immersion = Inefficient Stern Rise = Low Transom immersion High Prop Clearance 20
Service Power [kw] Overview of Considerations: 400 450 Comparison of Estimated Service Power in a Seaway for an As- Built 35' (L/B = 2.33) with an Optimised & Lengthened 39 11 Version (L/B = 2.66) As-Built Calm 350 300 250 As-Built ss4 As-Built ss5 Modified Calm Modified ss4 Modified ss5 200 150 100 50 0 0 1 2 3 4 5 6 7 8 9 Speed [knts]
Service Power [kw] Comparison of Estimated Service Power Required in a Seaway for an As-Built 65' (L/B = 2.89) with an Optimised & Lengthened 74 11 Version (L/B = 3.33) Overview of Considerations: 4500 4000 3500 3000 2500 As-Built Calm As-Built ss4 As-Built ss5 As-Built SS6 Modified Calm Modified ss4 Modified ss5 Modified ss6 2000 1500 1000 500 0 1 3 5 7 9 11 13 Speed [knts]
Potential Design Aids/Tools: Tank Testing & Simulation:
Design Predictions What it Can Do: Tank Testing, Simulations & Data Analysis : Performance & Powering Propeller, Gearing and Powering Design Envelopes Dynamic Stability Induced Motions/Seaworthiness Effects of Appendages and Bulbous bows Effect of Roll Dampening Devices
Testing Example: Effect Of Speed On Wave System & Powering Standard Bow~ 8.5 Knots Full Scale Equivalent (L/B = 2.407) Standard Bow~ 10.5 Knots Full Scale Equivalent (L/B = 2.407) VIDEO 8.5 VIDEO 10.5
Total Fuel Consumed [l] Design Tools: FUEL RATE COMPARISON: 4000 Fuel Consumption Over 100 Nautical Miles with Hull and Prop Variation (Maximum RPM ~ 12 Knots Speed) 3500 3000 As Built Prop Optimised Prop Ideal Hull Prop 2500 2000 1500 1000 500 0 0 500 1000 1500 2000 2500 3000 Engine RPM
EX :Reasonable Vessel Parameters 75 x 22 : Fewer Decks Less Windage & Iceing Surface ~ Lower Centre of Gravity
Material Considerations: Fibreglass: Weight Savings Moulded Design Facilitates: Clean, Fair Surface Finish Great variation in Possible Geometric Shapes Chemically Inert (doesn t rust!) Potential Cost savings for smaller vessels and series builds Caution: Cost of Resins can vary with cost of Fuel Can have water ingress and de-lamination/blistering issues Steel: Strong and Durable (Large margin of safety especially against impact) Easier to repair large structural damage Can build Any size, not mould dependent Chemically Sensitive Corrosion Higher maintenance costs
What Proper Vessel Design Can Provide: It may challenge some of our pre-conceptions of how an efficient, safe, reliable and economically viable vessel looks: Expect: Research of Alternative Equipment, Materials, Fuel Systems and Machinery and Associated Economic Costs & Payback Periods Clear Documentation on Vessel Trim and Stability (DFO & Transport Canada Requirements/Regulations) Comprehensive Design Drawings and Documentation Vessel Incline Tests Sea Trials Documentation of As-Built Vessel Performance
Proportional Vessel Parameters (Closer to our Ideal): High L/B Ratio Gradual Changes in Hull Shape Fine Bow = Low Half Angle of Entrance Stern Rise Needs to be Cleaned and Faired
Length to Beam is very significant (Higher L/B more efficient) Increased Length overall is more efficient Lowest Transom Immersion as possible Smallest Bow Half Angle Possible without creating an unnecessary abrupt change at the Shoulder Stern tube and Submerged Stern Shape should maximise space for Propeller (ensuring min. Clearance) & Ensure Clean Flow Propellers should be optimised for cruising (in most cases) in at the most efficient speed and engine RPM while ensuring sufficient Bollard Pull Lower Superstructure for reduced Windage and Iceing Areas Fewer Above water Decks = lower centre of gravity (NO NEED for permanent Ballast in proper design only Ballast Tanks )
CPP, different Nozzles, alternate Rudders, etc. Should be considered Properly Designed Bulbs are very useful at minimising required Power (and hence RPM) at Intended Design speed Properly Designed bulbs reduce motions in a seaway Properly Designed and Tuned Anti-Roll tanks are the most cost effective at reducing roll motions in a range of sea states Fuel Efficient Engines and Monitoring Systems Modular Gear Installation for Easy conversion to different Species Material Selection: Fibreglass vs. Steel AS GRADUAL CHANGES IN HULL SHAPE AS POSSIBLE! Fine Bow and Faired, Rising Stern!
CONCLUDING SLIDE