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OE 525 F 11

OE 525 F 11. Maneuvering. Maneuvering. Five key measure of maneuvering capability Turning ability Course changing & Yaw checking ability Initial turning ability Stopping ability Straight line stability & course keeping ability

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OE 525 F 11

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  1. OE 525 F 11 Maneuvering

  2. Maneuvering • Five key measure of maneuvering capability • Turning ability • Course changing & Yaw checking ability • Initial turning ability • Stopping ability • Straight line stability & course keeping ability • A vessels hydrodynamic derivatives are required to predict its maneuvering capability

  3. Methods of Determination of Maneuvering Capability Full-Scale Trails (tests of adherence to classification society standard) Theoretical Prediction Methods Regression Analysis results from similar designs (semi-empirical methods) Experiments with Scale Models Straight-line tests Rotating-Arm Technique Planar Motion Mechanism Technique Free running (radio controlled) model tests

  4. Maneuvering Standards & Criteria Source: ABS Guide for Vessel Maneuverability 2006

  5. Full Scale Maneuvering Tests • Standard tests: • Turning circle test • 10/10 Zig-Zag • 20/20 Zig-Zag • Crash stop • Non-standard tests • Pull out test • Simplified spiral test

  6. Turning Ability& Turning Circle Test • Measure of the ability to turn the vessel using hard over rudder to determine: • Minimum advance at 90° change of heading • Transfer • Tactical diameter • Transfer at 180° change of heading • Also recorded: • Speed lost in turn • Max roll angle • Peak & final yaw rate • Performed to both starboard & port Source: ABS Guide for Vessel Maneuverability 2006

  7. 10/10 & 20/20 Zig-Zag Maneuver • Initial turning: • Change of heading response to moderate helm, measured using: • Distance traveled before course change: Time to 2nd execute • Course changing & yaw checking: • Measure of the response to counter-rudder applied in a certain state of turning using heading overshoot using: • 1st & 2nd overshoot angles • Done at 10° & 20° • The Zig-Zag maneuver is to be done to both port & stbd. Source: ABS Guide for Vessel Maneuverability 2006

  8. Stopping Ability Test • Stop engine-full astern maneuver performed after a steady approach at test speed to measure: • Track reach: Distance along path from full astern order to ahead speed reversal • Head reach: Distance along direction of original course from full astern order to dead in water condition Source: ABS Guide for Vessel Maneuverability 2006

  9. Non-standard full scale trials • Pull out test: • residual turning rate after return to zero rudder used to assess if vessel is straight line stable or not • Simplified spiral test: • Degree of instability

  10. Types of Straight Line Stability SNAME PNA, Vol. III

  11. Hydrodynamic Derivatives Need to determine the hydrodynamic derivatives to truly measure maneuvering ability Velocity derivatives are needed to assess stability Acceleration derivatives are needed to determine the magnitude of the stability indices Additionally, control surface derivatives are needed to compute trajectory of a ship

  12. Model Tests • Used to determine hydrodynamic derivatives • Straight line tests • Rotating arm tests • Planar-motion tests • Free running model tests

  13. Straight-line Tests

  14. Rotating-Arm Tests

  15. PMM Tests

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