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.

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
28.10.2011
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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.
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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 right
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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.
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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.
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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 limit
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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.
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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.
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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.
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10. Water Entry – Hull Capacity (3/3)
• Video from CFD-simulation
CFD = Computational Fluid Dynamics
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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).
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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.
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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)
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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.
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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.
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16. Sail-away Phase (2/3)
• Setback in head sea
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17. Sail-away Phase (3/3)
• Setback in bow quartering sea
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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
states
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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).
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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.
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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.
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