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# Computational optimization of stability, propulsion and maneuverability of a riverine vessel

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Study of the stability and the hull integration with the propulsion system of a riverine support vessel, in order to optimize the efficiency of the propulsion plant and improve its maneuverability in its operations area

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### Computational optimization of stability, propulsion and maneuverability of a riverine vessel

1. 1. Computational optimization of stability, propulsion and maneuverability of a riverine vessel Lieutenant Commander Luis Javier Serrano Tamayo Colombian Navy University of the Andes - Naval Academy “Admiral Padilla” COLOMBIA
2. 2. Contents1. Introduction2. Hull and Stability3. Resistance and Propulsion System4. Maneuverability5. Conclusions Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
3. 3. 1. Introduction Riverine importance of Colombia Caribbean Sea 2nd country in biodiversity Coasts and Andean Region: 55% Territory 95% Population Pacific Ocean Amazon Jungle: 45% Territory 05% Population Highways Rivers Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
4. 4. 1. Introduction Problem The 1rst generation of RPV’s (Riverine Patrol Vessels) are very useful ships, but the armor is very heavy, the motors were racing just 1500 of the 1800 RPM, the propellers were present cavitation and the ships should improve their maneuverability due to the narrow rivers. ¼” 20 mm Arena Polyurethane ¼” 20 mm Arena Polyurethane ¼” Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
5. 5. 1. Introduction General goal The study of the integration between the hull and the propulsion system of the RPVs in order recommend improvements to optimize its propulsion system and reduce the tactical diameter in their operational area. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
6. 6. 2. Hull and Stability Hull geometry construction in field half width height Station 4; x=1,75 m (axis "y") (axis "z") Point 1 0 1.7 Point 2 1.7 1.65 Point 3 2.7 1.58 Point 4 2.7 1.295 Point 5 1.62 1.115 Point 6 1.18 0.575 Point 7 0.89 0.37 Point 8 0.78 0.31 Point 9 0 0 Is only necessary to write a half width, the software GHS (General Hydrostatics) completes the shape Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
7. 7. 2. Hull and Stability 1st edition results Reference point 0,0,0 The bow has to be refined Astern reached soft curves and it was ready Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
8. 8. 2. Hull and Stability Refining process (fairing) The control points were used to accomodate the geometry properly, as well as other Rhinoceros software commands. It was possible to obtain a faired surface of the hull and to model 3D the hull of the RPVs. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
9. 9. 2. Hull and Stability Tanks construction The tanks were constructed utilizing different GHS commands which permit fill in or fill out the tnaks in order to evaluate different loading conditions. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
10. 10. 2. Hull and Stability Coefficients of form The curves show the full forms of the ship (above 0.8), as well as the variation of the form coeffcients below 0.5 m of depth, due to the semi-tunnels in the astern (propellers). Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
11. 11. 2. Hull and Stability Hyidrostatics curves metacentric radius long. moment I H. Curves indicate different values to evaluate the intact stability of the ship (no trim) for different loading conditions. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
12. 12. 2. Hull and StabilityWeight previous studies (Methods by main characteristics) Method Result Method of Benford Used for bigger ships displacements Method of Danckwardt L/D is too little Method of Lamb Lenght is too little Method of Mandel Non logical value Method of Murray Non logical value Method of Osorio Could be useful as a reference Method of J.L. García G. Too little value The main characteristics methods evaluate the weight of any ship according formulas related to other ships of the same type, but as conclusion, none method satisfied the weight of the RPV precisely. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
13. 13. 2. Hull and Stability Weights study. Ship Work Breakdown Structure (SWBS) GRUPO CONCEPTO 100 Hull Strcuture 200 Propulsion plant 300 Electrical plant 400 Communications and Command 500 Auxiliary services 600 Equipment and Furniture 700 Weapons M Margins F Deadweight The SWBS has subgroups and elements which describe precisely all the ship components. Every one has a weight and a position in the 3D model and all the weights were inserted to model the ship with its components. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
14. 14. 2. Hull and Stability Summary of calculated loads according SWBS When every weight is calculated and its 3D position is related to the reference point, the final result is the CG of the ship. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
15. 15. 2. Hull and Stability Example of weight distribution in the different stations The example shows the longitudinal distribution of some elements of the 100 SWBS group in the stations used to divide the lenght of the ship. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
16. 16. 2. Hull and Stability Curves of Loads There are three main loading conditions: Light ship. The weight of the ship without any deadweight. Equitative distribution of loads. Main weights are astern. Minimal operational condition. The ship has the minimum deadweight to navigate. Water tanks 2/3 of load and fuel 1/3 of load. Full load. The ship has the 100% of deadweight. Liquid cargo create punctual weights in some stations. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
17. 17. 2. Hull and Stability Stability criterion DDS-079 USN Protection of vital spaces and main wall spacing 1. Spacing between transversal bulkheads = 10’ + 0.03 LBP 2. Collision bulkhead must be maximum at 5% de LBP 3. Crossed connections must be prevented The ship passed the spacing criterion Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
18. 18. 2. Hull and Stability DDS-079 USN. Stability Threats 1. Beam wind combined with rolling 2. Heavy lifting over one side 3. Towing forces 4. People crowding over one side 5. High speed turning 6. Top icing The first and the last two pose no threat to the vessel considering its characteristics and surroundings. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
19. 19. 2. Hull and Stability Stability Criterion. 46CFR Part 170. USCG Minimal metacentric permitted height PAH GM ≥ P = 0.028 + ( L 1309 ) 2 W tan(T ) Factor for shallow waters maneuvering Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
20. 20. 2. Hull and Stability Results for the minimal operational condition The ship shows good intact stability, because passed the criteria established and is confirmed the prediction that if a ship have high Width/Depth ratio will have a good intact stability. 7.2 m / 1.2 m = 6 • General cargo ship, 40 m/ 20 m = 2 • Container ship, 60 m/ 30 m = 2 • Oiler ship, 80 m/ 35 m = 2.3 • USN Aircrat carrier, 112 m/ 45 m = 2.5 Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
21. 21. 2. Hull and Stability Critical points The critical points are those that permit a progressive flooding in the ship, for example, the ventilation of machinery room. Critical point intersection at 24° of heeling Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
22. 22. 3. Resistance and Propulsion System Analysis of NAVCAD sistematic series Method Result Basic Formula Value spectrum too widht Holtrop Method BWL/T ratio too short Oortmerssen Method BWL/T ratio too short Denmark Univ. Method OK, LWL/BWL quite short USNA YP Series Characteristics matched 60 Series Only for round bilge keel ships Nordstrom y YP 81-1 Series High dead keel 64, SSPA, NPL y Dutch Series Planning hulls The ship characteristics must match properply to use the sistematic series of NAVCAD, otherwise is not possible to use. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
23. 23. 3. Resistance and Propulsion System Hull characteristics In the hull data, the main influence factor is the wetted surface for resistance prediction Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
24. 24. 3. Resistance and Propulsion System Environmental characteristics In the environment data, the main influence factor is the depth of the channel (river) for resistance prediction. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
25. 25. 3. Resistance and Propulsion System The “Squat” effect Is the change in the draft and trim of a ship, as result of variations in the hydrodinamic pressure over the hull. In this critical zone, if the ship in navigating in shallow waters, eventually can touch the bottom. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
26. 26. 3. Resistance and Propulsion System 0.8 PREDICCIÓN MANACACÍAS-1m.nc4 Squat variation at 0.7 PREDICCIÓN MANACACÍAS-3m.nc4 PREDICCIÓN MANACACÍAS-6m.nc4 PREDICCIÓN MANACACÍAS-9m.nc4 different depths 0.6The squat curve for 1 m depth 0.5shows the three cirtical regions. Squat m 0.4The other are always in thesubcritical region. 0.3 0.2What is the minimum depth forsecure navigation, without 0.1squat effect? 0 0 2 4 6 8 10 12 14 Vel ktsThe ship is in full load condition. Subcritical región Critical región crítica Supercritical región subcrítica region region region supercrítica Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
27. 27. 3. Resistance and Propulsion System Squat effect in resistance 4000 N difference between 3-6 m Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
28. 28. 3. Resistance and Propulsion System Minimal secure depth = 3 meters There are other problems associated: Vibrations Cavitation of propellers due to reverse trim Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
29. 29. 3. Resistance and Propulsion System Resistance and motor performance • 02 DD671L motors, 180 BHP @ 1800 rpm • 02 Twin Disc gearings, 2.45:1 • 02 FP propellers, 3B, 36”X32” Previous performance area of the motors Detalles of eroded blade due to cavitation 1800 Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
30. 30. 3. Resistance and Propulsion System Optimal pitch selection 0.50 BS-3: 0.914x0.813x0.450 BS-3: 0.914x0.555x0.450 BS-4: 0.914x0.530x0.610 0.48 PropEff 0.46 0.44 2 3 4 5 6 7 8 9 10 Vel kts The 3 blade propellers show better performance in efficiency evaluation Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
31. 31. 3. Resistance and Propulsion System Optimal expanded area of the blade 0.50 BS-3: 0.914x0.555x0.450 BS-3: 0.914x0.546x0.800 GA-3: 0.914x0.503x0.800 0.48 0.46 PropEff 0.44 0.42 0.40 1 2 3 4 5 6 7 8 9 Vel kts The comparison between B-Series and Gawn propellers was more favourable to B-Series. In the other hand, not always more blade area means more efficiency.
32. 32. 3. Resistance and Propulsion System Optimal performance• Optimal P/D ratio• More speed Optimal P/D• More power Previous P/D• Less carbon in cylinders• Less manteinance• Less emissions Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
33. 33. 3. Resistance and Propulsion System Fuel consumption and range 8,0Fuel consumption 7,0 Fuel consumption (gph) 6,0Half gallon per hour 5,0less since 12 kph 4,0 3,0 2,0Range 1,03 more days of range 0,0 8,00 9,00 10,00 11,00 12,00 13,00 14,00 15,00 16,00 17,00 Ship speed (kph) Previous propeller Optimal propeller Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
34. 34. 4. Maneuverability Field visit and rudder geoemtry• Before to be a mother vessel for the soldiers, the ship was a river tug, used for push 3 barges with cargo.• The rudder area oversized, considering the barges lenght. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
35. 35. 4. Maneuverability Shape ratios. Aspect and balance • Very low aspect ratio: Lift coefficient b / c = 0.43 Rudder angle, degrees • Low balance ratio A1 A2 A / A2 1 = 0.12 < 0.265 Mínimum for CB = 0.81 Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
36. 36. 4. Maneuverability Sizing the rudder The calculated rudder shouldn’t touch the semmi tunnel of the hull in its maximum angle of steering (35˚), procuring the maximum height.1. Minimum distance propeller – rudder. (0.30 m, facilitation of remove the propeller)2. Size the rest of the distance till the mirror (last nulkhead, 0.75 m)3. The distance of the balance ratio should be discounted (0.2 m) Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
37. 37. 4. Maneuverability Rudder shape innovation. Schilling rudder Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
38. 38. 4. Maneuverability Characteristics and improvements of Schilling rudder 1. One-piece construcition. No additional maintenance 2. Important control improvement at low speed 3. CL is 1.3 times higher, which reduces tactical diameter 4. Maximum force at bigger stall angle (40 - 45˚) 5. High lift coeffcient going astern 6. Excellent course control (fuel save), even without dead keel Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
39. 39. 4. Maneuverability Lift coefficient comparative curves Source: Schilling Rudder Monovec Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
40. 40. Conclusions1. Instead of the heavy armor, the intact stability of the RPVs is excellent. However, the heavy armor reduces cargo capacity.2. The optimal propeller increased efficiency and range as well as reduced fuel consumption and cavitation.3. The Schilling rudder increased significantly the lift and reduced the tactical diameter since 4 to 2 lenghts. Additionally the improvement in course control reduced fuel consumption of the RPV. Computational optimization of stability, propulsion and maneuverability of a riverine vessel. Lt Cdr Javier Serrano Tamayo
41. 41. Gracias! Thank you!Computational optimization of stability, propulsion and maneuverability of a riverine vessel Lieutenant Commander Luis Javier Serrano Tamayo Colombian Navy University of the Andes - Naval Academy “Admiral Padilla” COLOMBIA