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OLF/NSA Davit-Launched Lifeboat Project (DLLBP)    Summary by Project Manager Ole Gabrielsen    Contents    • Brief histor...
Brief historical overview of DLLBP    •   Initiated in December 2009, completed in Juni 2011.    •   Scope of work defined...
Lowering Phase (1/2)    • A considerable amount of      simulations performed in wind      spectres with gust winds    • K...
Lowering Phase (2/2)    • A lowering speed of around 1.0 m/s appears to be a sound      compromise between acceleration le...
Water Entry – Forces on Occupants (1/3)    • Work based on acceleration pulses generated for :        • 3 boats        • 2...
Water Entry – Forces on Occupants (2/3)    • There is a minor risk of injury to lifeboat occupants during water      entry...
Water Entry – Forces on Occupants (3/3)    • Another study investigated the effect of various parameters such as      post...
Water Entry – Hull Capacity (1/3)    • The slamming methodology developed by      the FFLBP was adjusted and applied to   ...
Water Entry – Hull Capacity (2/3)    • The analyses show that the lifeboats have sufficient      capacity for head sea and...
Water Entry – Hull Capacity (3/3)     • Video from CFD-simulation       CFD = Computational Fluid Dynamics10
Release Phase (1/4) - Summary     • Survey of release systems         • Existing systems in use         • Novel systems un...
Release Phase (2/4) - Summary     • Simulation parameters         • 2 lifeboats         • 2 lowering heights (28 m and 80 ...
Release Phase (3/4) - Results                                                        Lowering speed: 0.9 m/s              ...
Release Phase (4/4) – Full-scale Tests     •   Full-scale tests have been performed for several release systems. The      ...
Sail-away Phase (1/3)     • A study of the sailing phase concludes that the setback for davit-       launched lifeboats in...
Sail-away Phase (2/3)     • Setback in head sea16
Sail-away Phase (3/3)     • Setback in bow quartering sea17
Overview of numerical simulations     Phase(s)      Scope/objective                                         Number of     ...
Procedure for Test Run of Lifeboat Engines     • A separate study evaluating the procedure for test run of       lifeboat ...
HAZID of Raft Systems     • The HAZID report highlights that the owners should, in cooperation       with equipment suppli...
Main Conclusions     Lowering      • A loweing speed of around 1.0 m/s is recommended.                   • Pull & go princ...
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Presentation of the OLF/NSA Davit-Launched Lifeboats Project

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Summary presentation of the OLF/NSA Davit-Launched lifeboat project.

The project was initiated by the Norwegian Oil Industry Association (OLF) in December 2009, and was executed as a joint effort between OLF and The Norwegian Shipowners’ Association (NSA). The project is a continuation of NSA LAP (Life-saving Appliances Project) and lessons learned in OLF Free Fall Lifeboat Project. The project was organized in six Work Packages (WPs) and was completed in June 2011.

The studies in the project covered the following phases during lifeboat evacuation; (1) lifeboat lowering, (2) water entry, (3) release of wire falls and (4) sail-away. Findings and recommendations related to each of the four phases are presented.

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Transcript of "Presentation of the OLF/NSA Davit-Launched Lifeboats Project"

  1. 1. OLF/NSA Davit-Launched Lifeboat Project (DLLBP) Summary by Project Manager Ole Gabrielsen Contents • Brief historical overview • Findings and conclusions for four phases: • Lowering • Water entry (landing) • Release of wire falls • Sail-away • Test run of lifeboat engines • Raft HAZID • Main conclusions 28.10.20111
  2. 2. Brief historical overview of DLLBP • Initiated in December 2009, completed in Juni 2011. • Scope of work defined based on findings from NSA Lifesaving Appliances Project (LAP) and previous work for davit-launched lifeboats. • Funded by Norwegian Shipowners’ Association and The Norwegian Oil Industry Association (OLF). • Organized in six work packages: • WP 1 – Release systems • WP 2 – Lowering, landing and sail-away • WP 3 – Forces on occupants • WP 4 – Third-party verification of WP 2 • WP 5 – Raft HAZID, test run of lifeboat engines and evacuation methodology • WP 6 – Hull capacity • Work performed by consultancy companies reporting to project manager. • Project managed by an Owners’ Group with representatives from oil companies and drilling rig companies with davit-launched lifeboats. • The overall goal of the project was to provide guidance/advice to use of existing davit-launched lifeboats such that these, as far as reasonably possible, can continue to satisfy the intentions laid down in the regulations.2
  3. 3. Lowering Phase (1/2) • A considerable amount of simulations performed in wind spectres with gust winds • Key parameters: • Loaded and empty boat • Three lowering heights (22, 50 og 80 m) • Three lowering speeds (0.5, 0.9 og 1.5 m/s) • Three wind speeds (Beaufort 10, 11 og 12) • Three wind directions (beam wind, bow quartering and near to head wind) • Example of plots on the right3
  4. 4. Lowering Phase (2/2) • A lowering speed of around 1.0 m/s appears to be a sound compromise between acceleration levels and release window requirements (time from water entry until the wave moves downwards). • Lifeboat lowering from great heights (more than 50 m) in strong wind may lead to large pendulum motions. • The project recommends implementation of ‘pull & go’ loweringlåring, if not already implemented by the owners. • ‘Pull & go’ launching of lifeboats is in line with NORSOK R- 002, but in conflict with requirements from IMO through SOLAS/LSA-code.4
  5. 5. Water Entry – Forces on Occupants (1/3) • Work based on acceleration pulses generated for : • 3 boats • 2 lowering speeds (0.9 m/s og 1.5 m/s) • 5 wave directions (0, 45, 90 (beam sea), 135, 180 (head sea) degrees) • 7 wave conditions (8.5, 11.7, 14.7, 16.0, 17.0, 17.8 and 20.3 m regular waves corresponding to rough waves in 100-year storms) • 6 seats per boat • Injury evaluation according to levels established by the Free-fall Lifeboat Project (Human Load Level) • Selected simulations compared to laboratory tests.5
  6. 6. Water Entry – Forces on Occupants (2/3) • There is a minor risk of injury to lifeboat occupants during water entry, even in waves representing extreme conditions. • The largest risk occurs in beam sea conditions, mainly related to high loads on head and neck. Boat 1 Boat 2 Boat 3 Below lower limit Between lower and upper limit Above upper limit6
  7. 7. Water Entry – Forces on Occupants (3/3) • Another study investigated the effect of various parameters such as posture, belt arrangement and use of cushions. Proposals for improvement have been established. • An assessment of the interaction between occupants sitting next to each other, opposite each other and back-to-back did not reveal any critical effects, but highlighted the possibility of collision between occupant if 2-point belt systems are used. • A third study looking at the effect of body sizes concluded that the overall conclusions for forces on occupants are valid also for smaller and bigger occupants.7
  8. 8. Water Entry – Hull Capacity (1/3) • The slamming methodology developed by the FFLBP was adjusted and applied to davit-launched lifeboats. • Main steps in method: • Selection of design loads and load factors • Establish skin model of lifeboat with indicator panels • CFD analyses giving pressure on indicator panels • Preparation of structural model of lifeboat • Load mapping onto structural model • Evaluation of stress and deflection • The hull slamming capacity of two davit- launched lifeboats have been evaluated.8
  9. 9. Water Entry – Hull Capacity (2/3) • The analyses show that the lifeboats have sufficient capacity for head sea and bow quartering sea. Requirements may be required for beam sea, stern quartering sea and following sea. • Further work is required to determine specific reinforcements to each type of boat.9
  10. 10. Water Entry – Hull Capacity (3/3) • Video from CFD-simulation CFD = Computational Fluid Dynamics10
  11. 11. Release Phase (1/4) - Summary • Survey of release systems • Existing systems in use • Novel systems under development • Gap analysis vs. NORSOK R-002 • Development of new release systems is required to fulfil all requirements of NORSOK R-002 (Preliminary edition April 2010).11
  12. 12. Release Phase (2/4) - Summary • Simulation parameters • 2 lifeboats • 2 lowering heights (28 m and 80 m) • 3 lowering speeds (0.5 m/s, 0.9 m/s and 1.5 m/s) • 5 weather directions (0, 45, 90 (beam sea), 135, 180 (head sea) deg) • 6 sea states (7.5, 10, 13, 15, 18 and 20 m – regular waves corresponding to rough waves in a 100-year sea state) • 10 landing positions in each wave • It is important to release the lifeboat from the wire falls as soon as it is waterborne (on the first wave) to prevent re-entry. Rapid release is vital to avoid detrimental loads on occupants and on the lifeboat itself. • Time to release (time from the boat is in contact with the water until the wire falls are released) should be less than 3 seconds. For a time to release of 3 seconds there is a very small risk of severe re-entry loads. • The risk of severe re-entry loads is eliminated for a time to release of 1 second. • The importance of rapid release should be communicated to lifeboat crews and training centres so that the crew may practice rapid releases.12
  13. 13. Release Phase (3/4) - Results Lowering speed: 0.9 m/s 100 % 97 % Percentage of non-exceedence (%) 90 % 80 % 70 % 71 % 60 % 50 % 40 % 30 % Time to release = 1.0 s Time to release = 3.0 s 20 % 22 % Time to release = 5.0 s 10 % 0% 0 10 20 30 40 Time from water contact to release (s)13
  14. 14. Release Phase (4/4) – Full-scale Tests • Full-scale tests have been performed for several release systems. The newest systems have results from 1 to 1.5 seconds.14
  15. 15. Sail-away Phase (1/3) • A study of the sailing phase concludes that the setback for davit- launched lifeboats in head sea and bow quartering sea is considerable even at moderate sea states (Beaufort force 7). • The setback is influenced by engine size and delay or no delay in engagement of propulsion. • For beam sea, following sea and stern quartering sea the setback is small.15
  16. 16. Sail-away Phase (2/3) • Setback in head sea16
  17. 17. Sail-away Phase (3/3) • Setback in bow quartering sea17
  18. 18. Overview of numerical simulations Phase(s) Scope/objective Number of simulations Låring/fri- Effect of delayed release and lowering speed on peak 3 600 gjøring accelerations at water entry, wire forces and CAR index Study of pendulum effects; effect of lowering speed 9 900 and weight Water Establish peak accelerations (acceleration pulses) 3 500 (giving 21 000 entry acceleration pulses) Evaluation hull capacities 20 CFD analyses 40 structural analyses G-force parameter study: belt systems, postures, 156 cushions Interaction between occupants with 2-point belt 18 systems Boat-specific analyses of G-forces during water entry 1 260 Injury potential in extreme re-entry loads 55 Study of correlation between numerical simulations of 27 dummy models and human models Sail-away Simulation of setback and propulsion in various sea 12 600 states18
  19. 19. Procedure for Test Run of Lifeboat Engines • A separate study evaluating the procedure for test run of lifeboat engines concluded that idle-running should not exceed 3 minutes to avoid soothing that may impair the engines maximum output. • The optimal test interval is every second week (in contrast to SOLAS which prescribes once a week).19
  20. 20. HAZID of Raft Systems • The HAZID report highlights that the owners should, in cooperation with equipment suppliers, evaluate amount and type of training to ensure high probability of correct use. • The importance of correct training was called for by the employee representatives who participated in the HAZID. • The HAZID revealed a number of uncertainties which should be evaluated by the owners. • It is the responsibility of the owners to evaluate the findings of the raft HAZID and to initiate any minigating measures.20
  21. 21. Main Conclusions Lowering • A loweing speed of around 1.0 m/s is recommended. • Pull & go principle should be implemented. Water Entry • There is a small risk of injury for occupants during water entry. • Hull reinforcement should be evaluated. Release • Development of novel release systems is required to fulfil all requirements of NORSOK R-002 (April 2010 edition). • Detrimental re-entry loads (on occupants and boat) in the release phase can be avoided by ensuring rapid release of wire falls. Sail-away • The setback in head sea and bow quartering sea can be considerable. • The setback may be reduced by optimazing the bollard pull and launching procedure. Other • The findings from the project should be implemented in training programs for lifeboat crew. • The owners should address the findings of the raft HAZID. • Idle-running should not exceed 3 minutes to avoid soothing that may reduce the engine’s maximum output. The optimum test interval is every second week.21
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