Your SlideShare is downloading. ×
0
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Anchor Handling Stability
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Anchor Handling Stability

2,054

Published on

Anchor Handling Stability - Present status for practitioners & changes expected in 2014!

Anchor Handling Stability - Present status for practitioners & changes expected in 2014!

Published in: Technology, Business
1 Comment
0 Likes
Statistics
Notes
  • Thanks!! it's useful
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
  • Be the first to like this

No Downloads
Views
Total Views
2,054
On Slideshare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
179
Comments
1
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide
  • Good afternoon…ladies & gentlemen!This work was done by Dephne Chea Wei Peng as her Final Year Project! The project was supervised by Dr Ivan Tam & Dr ArunDevThe topic was proposed by the EMAS Academy.As Dephne is not here, Dr Ivan Tam asked me to make the presentation!If you have any queries, kindly direct them to Dr ArunDev and Dr Ivan Tam after my presentationIn her project Dephne traced the work that is being done in AH stability and hopefully her findings will update us in this area!
  • Neither the IMO’s regulatory system nor Norwegian regulations have concrete requirements for the stability of anchor-handling vessels.The Commission of Enquiry for BD has acquired information from British and Danish authorities confirming that they do not have separate stability requirements for anchor-handling vessels either.Dephne has looked only into the stability aspects in her studies
  • The 2008 IS Code is divided into two parts: Part A, which is mandatory, contains general intact stability criteria for cargo and passenger ships. Part B, which is recommendatory, contains intact stability criteria for certain types.
  • Max GZ of an OSV is allowed to occur at much smaller angle of heel than normalAs per Clark & Hancox (2012) Minimum freeboard criteria for OSV is inadequate for anchor-handling operation
  • Each AH Vessel should have its AH Operation ManualAs per Marine Safety Forum it should incorporate the NMD recommendationsPrior to sailing, a document must be displayed on the bridge, where it is visible to be navigator on duty, to show the acceptable vertical and horizontal transverse force/tensions to which the vessel can be exposed.This should show a sketch of the GZ curve and a table of the tension/forces which give the maximum acceptable heeling moment.
  • AH Manual Template also incorporates the NMD recommendations, which is explained in the next slide
  • 3 NMD CriteriaHeeling Moment Levers should be ‘h’ is distance from the CL to the end of the Stern Roller ‘v’ is the distance from top of stern roller to CL of Thrusters.
  • NMD Proposal to IMO for Amendment of the 2008 Intact Stability Code Part B providesInformation on Application Point & Direction of a Towline in the Stern of a multi-operational mode vessel alpha - beta
  • Heeling Moment has two main components as shown
  • Values from a typical example show the effects of sideways angle ‘alpha’ & downward angle ‘beta’
  • Then it is possible that as ‘α’ is increased MH could reach to an unacceptable level!
  • Norwegian proposal is based on a concept of αconstant heeling moment MHLine tension only dependent on sideways angle ‘α’
  • Line Tension vs sideways angle ‘α’ for a fixed moment
  • Finally, a simplified Angle Alpha vs Tension could be createdFor use by the operatorsMark the angle segments which are made specially for the operators!
  • This visual could be put on the bridge for the benefit of operators.This one also includes the dynamic factors.
  • Finally, stability limiting curves also have to be made
  • With its specific requirements
  • These amendments are expected in 2014
  • Now will show you some screenshots of theAutoload Software on one of the EMAS vessels
  • Autoload 6 Assumptions
  • Anchor handling inputs to the software!
  • One can choose the NMD Anchor-handling criteria.
  • General Interface of AUTOLOAD 6 – Hydrostatics, Anchor Handling & Margins
  • This is IMO Intact Stability Analysis
  • NMD Anchor Handling Criteria line tension 250 t alpha – 10 degrees
  • NMD Anchor Handling Criteria line tension 350 t alpha – 10 degrees
  • NMD Anchor Handling Criteria line tension 650 t alpha – 10 degrees
  • Transcript

    • 1. Formulating Stability Requirements for Anchor Handling Tug and Supply (AHTS) Vessels Dephne Chea Wei Peng, Arun Kr Dev, Ivan Tam, (Newcastle University) Kenneth Hanks, Kalyan Chatterjea (EMAS Training Academy & Simulation Centre) 1
    • 2. BACKGROUND  No specific internationally applicable stability requirements for AHTS vessels.  After AHTS “Bourbon Dolphin” tragedy in April 2007, initiatives were taken for improving  Design  Operational safety & specifically  Stability and the performance of anchor handling winches.  Probably the most important initiative is from the  Norwegian Maritime Directorate (NMD): NMD Circular - Series V, RSV 04-2008, 14 July 2008. 2
    • 3. IMO Guidelines…BV Presentations, 2010 @ KL  Refer to Intact Stability Code, 2008, IMO Res. MSC.267(85).  Code covers  intact stability criteria &  addresses offshore supply ships & special purpose ships,  requirement for a minimum freeboard at the stern of at least 0.005L to be maintained in all operating conditions.  Code does not include any specific stability criteria for towing and anchor handling operations  Minimum required GM0 = 0.15 m should NOT be considered as sufficient stability margin for towing and anchor handling. .3
    • 4. IMO Criteria for OSV  Max GZ of an OSV is allowed to occur at much smaller angle of heel than normal, providing that the positive stability up to this angle of heel (area A) is greater than for a cargo ship  This requires a large upright GM  Minimum freeboard criteria for OSV is inadequate for anchor- handling operation  Clark & Hancox (2012) 4
    • 5. Recommendation from Marine Safety Forum (MSF)  Quoting from Anchor-handling Manual template by Marine Safety Forum (MSF), incorporating recommendations from NMD.  Prior to sailing, a document must be displayed on the bridge, where it is visible to be navigator on duty, to show the acceptable vertical and horizontal transverse force/tensions to which the vessel can be exposed.  This should show a sketch of the GZ curve and a table of the tension/forces which give the maximum acceptable heeling moment. 5
    • 6.  Further quoting from the Anchor-handling Manual template by MSF incorporating recommendations from NMD.  Calculations must show the maximum acceptable tension in wire/chain, including transverse force, that can be accepted in order for the vessel’s maximum heeling to be limited by one of the following angles, whichever occurs first:- o Heeling angle equivalent to a GZ value equal to 50% of GZ max. o The angle of flooding of the work deck – i.e. the angle which results in water on working deck when the deck is flat. o 15 degrees. Recommendation from Marine Safety Forum (MSF) 6
    • 7. NMD Criteria 1. Heeling angle equivalent to a GZ value equal to 50% of GZ max. 2. The angle of flooding of the work deck – i.e. the angle which results in water on working deck when the deck is flat. 3. 15 degrees.  Vessel‟s Maximum Heeling to be limited by one of the following angles, whichever occurs first:  Heeling moment must be calculated as the total effect of the horizontal & vertical transverse components of the force /tension in the wire/chain  The torque arm of the horizontal components shall be calculated as the distance from height of the work deck at the guide pins to the centre of the main propulsion propeller or to the centre of stern side thruster if it projects deeper  The torque arm of the vertical components shall be calculated from the centre of the outer edge of the stern roller & with a vertical straining point on the upper edge of the stern roller 7
    • 8. External Acting Forces & Healing Moments …NMD Proposal to IMO  α – angle between towline & ship’s centre line  β – angle between towline & the waterplane  y & v – refers to application point of the of the line tension  Ft – towline tension Unified Stability Criteria & Operational Guidance for AH Vessels Application Point & Direction of a Towline in the Stern of a multi-operational mode vessel 8
    • 9. External Acting Forces & Healing Moments …NMD Proposal to IMO  Heeling Moment MH = (Ft .sin α.cos β x v)+(Ft .sin β x y) Application Point & Direction of a Towline in the Stern of a multi-operational mode vessel Transverse Component Vertical Component Unified Stability Criteria & Operational Guidance for AH Vessels 9
    • 10. Tension Directions vs Healing Moments MH …NMD Proposal to IMO A typical example of Heeling Moments with some specific ‘y’ & ‘v’ levers β α So, in general,  As ‘α’ increases MH is increasing  As ‘β’ increases MH is decreasing Unified Stability Criteria & Operational Guidance for AH Vessels 10
    • 11. Influence of ‘α’ & ‘β’ on MH …NMD Proposal to IMO α  As ‘α’ is increased MH could reach to an unacceptable level! β MH Unified Stability Criteria & Operational Guidance for AH Vessels 11
    • 12. Concept of Constant Heeling Moment …NMD Proposal to IMO  The Norwegian proposal is based on a concept of α constant heeling moment MH , providing limits  to the line tension only dependent on sideways angle ‘α’ Vertical Component Transverse Component Unified Stability Criteria & Operational Guidance for AH Vessels 12
    • 13. Fixed Moment vs Tension …NMD Proposal to IMO  Tension distribution with a constant Heeling Moment Unified Stability Criteria & Operational Guidance for AH Vessels 13
    • 14. Operating Tension vs Angle Alpha …NMD Proposal to IMO  Finally, a simplified Angle Alpha vs Tension could be created  For use by the operators 15 30 60 90 Unified Stability Criteria & Operational Guidance for AH Vessels 14
    • 15. Graphical Presentation …NMD Proposal to IMO  A simplified graphical presentation on bridge  T1 – 0 to 150  T2 – 15 to 300  T3 - 30 to 600  T4 - 60 to 900 Unified Stability Criteria & Operational Guidance for AH Vessels DF – 1.4 to 1.6 times the static load is common Sector-1 Sector-2 Sector-3 Sector-4 15
    • 16. Stability Limiting Curves …NMD Proposal to IMO Unified Stability Criteria & Operational Guidance for AH Vessels  For AH-Operations, the stability limiting curves should be developed as a function of draught/displacement against initial KG or GM & applied tension  Covering lightest anticipated draught to Summer Load Line & trim range Heeling Angle Flooding Angle 16
    • 17. Stability Limiting Curves …NMD Proposal to IMO Unified Stability Criteria & Operational Guidance for AH Vessels  The minimal residual area between the righting lever curve and the heeling lever curve ≥ 0.055 m-rad  [θe to θf or θc whichever is less] 17
    • 18. IMO Amendment - Part B 2008 IS Code 18
    • 19. Ultra Deep Water Multifunctional AHTS Vessel LOA – 93.4m LBP – 82.0m B – 22.0m D – 9.5m (main deck) Design Draught – 6.5m Bollard Pull – 300 tonnes AH/Towing Winch – 500 tonnes pull [600 tonnes brake] Propulsion - 23,467 BHP DP II Deadweight Approx. 4,700 T GRT Approx. 6,000 T Lewek Fulmar 19
    • 20. Lewek Fulmar uses AUTOLOAD 6 AUTOLOAD 6 ASUMPTIONS:  Tension from chain is placed at the full breath of aft roller, & the chain angle (tension) is calculated from 0o(vertical) to 90o(horizontal)  The vertical moment arm from main thrusters (or aft side thrusters if existing) and up to aft roller is kept constant, independent of vessels heel angle.  The horizontal moment arm from end of aft roller to centerline is kept constant, independent of vessels heel angle.  Both the effect of the horizontal forces and the tensions offset from CL is converted to an external moment acting on the vessel.  To keep correct displacement during all calculations, the vertical tension component (the weight) is placed at centerline on top of aft roller. 20
    • 21. Lewek Fulmar uses AUTOLOAD 6 Tank Sensors in AUTOLOAD 6:  Autoload installations can be fitted with a Tank Sensor program that interfaces directly with Autoload  Thus providing immediate tank loadings for an accurate and up-to-the-minute analysis of the vessel’s stability. 21
    • 22. NMD stability criteria for anchor handling is incorporated in AUTOLOAD 6 22
    • 23. NMD stability criteria for anchor handling is incorporated in AUTOLOAD 6 23
    • 24. General Interface in AUTOLOAD 6 Hydrostatics Anchor-Handling Margins 24
    • 25. IMO 469 Intact Stability in AUTOLOAD 6 Righting Arms vs. Heel - IMO 469, INTACT STABILITY Heel angle (Degrees) A r m s i n m 0.0 10.0p 20.0p 30.0p 40.0p 50.0p 60.0p 0.0 0.5 1.0 Righting Arm R. Area Flood Pt 25
    • 26. NMD Criteria in AUTOLOAD 6 Righting Arms vs. Heel - NMD ANCHORHANDLING CRITERIA Heel angle (Degrees) A r m s i n m 0.0 10.0s 20.0s 30.0s 40.0s 50.0s 60.0s 70.0s -0.5 0.0 0.5 1.0 Righting Arm Heeling Arm Equilibrium Crit. Pt 26
    • 27. NMD Criteria in AUTOLOAD 6 Righting Arms vs. Heel - NMD ANCHORHANDLING CRITERIA Heel angle (Degrees) A r m s i n m 10.0s 20.0s 30.0s 40.0s 50.0s 60.0s 70.0s -1.0 -0.5 0.0 0.5 Righting Arm Heeling Arm Equilibrium Crit. Pt 27
    • 28. NMD Criteria in AUTOLOAD 6 Righting Arms vs. Heel - NMD ANCHORHANDLING CRITERIA Heel angle (Degrees) A r m s i n m 10.0s 20.0s 30.0s 40.0s 50.0s 60.0s 70.0s -1.5 -1.0 -0.5 0.0 0.5 Righting Arm Heeling Arm Equilibrium Crit. Pt 28
    • 29. Conclusions  Recommendation for Stability Requirements during Towing & Anchor-handling Operations are likely to be covered by the Par „B‟ of the Intact Stability Code, 2008, IMO Res. MSC.267(85) in 2014  We should be prepared with a suitable course to support the professionals at the operational level  We hope there will be continuous support from the academia 29
    • 30. Thank You!! 30

    ×