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Flooding Progression

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									Office of Marine Safety



Stability and Flooding

Eric Stolzenberg
Presentation Overview
• Stability
• Flooding progression
• Impact of physical rudder loss
• Effects of astern travel
Vessel Configuration

                                         Fishing Vessel Alaska Ranger


    OSV Ranger                                  Wheelhouse
                                                             Fo’c’sle Deck
                                                      Trawl Deck
         Ramp   Freezers      Processing Area    Factory Deck
                      Machinery Spaces
Rudder                                          Hold
Stability
• Stability criteria
  – Intact stability: capsizing
  – Damage stability: flooding

• Stability requirements
  – Necessary for vessel certification
  – Incorporate stability criteria
 Vessel Intact Stability
• Owner monitored stability
  – Not required
  – Intact stability through T&S booklet
  – Damage stability not monitored or required

• Postaccident Coast Guard MSC review
  – Stability test confirmed
  – T&S booklet met requirements
  – Intact stability met requirements
Intact Stability Margin
• Large stability margin prior to sinking
• Downflooding points located aft
  – Engineroom intake vents
  – Aft trim conditions at deeper drafts
    quickly reduced the margin
Flooding Progression
Flooding Progression — Profile


       Aft Fish Bin
        (Freezer)
Flooding Progression — Plan


            Watertight Bulkheads




             Watertight Bulkhead
Flooding Rate Verification
• Coast Guard scenarios
  – Estimate 5 minutes to flood rudder room
  – Estimate 50 minutes for water to reach
    switchboard
• Electrical switchboard
  – Will short if flooded
  – Vessel loses electrical power
• Loss of rudder flooding rate roughly
  corresponds to event timeline
Rudder

                    Lock
                     Nut


                                      Thrust
                                      Bearing


                                     Rudder
                                     Stock


                                        Hull


 Starboard Rudder    Upper Rudder Assembly
Vessel Traveling Astern
• Exacerbated flooding
  – Increased rate
  – Decreased distance to downflooding
    points
  – Increased pressure on hatches and
    doors
• Prevented crew from entering liferafts
Stability and Flooding Summary
• Vessel had adequate intact stability
• Most likely encountered rudder loss
• Would not have sunk if flooding contained
  to rudder room
• Sank from uncontrolled progressive
  flooding
• Astern travel accelerated flooding
Office of Marine Safety



Propulsion System

Eric Stolzenberg
Presentation Overview
• Causes of astern travel
• Propulsion system overview
• Propulsion system modification
• Means to stop travel
CPP System Overview
Propulsion System Layout

                                      Gear
            Propulsion Shaft
                                             Port main engine

Propeller
                          Hydraulic          Main
                            pumps            Switchboard
Propeller

                                             Stbd main engine
            Propulsion Shaft
                                      Gear
Spindle Torque Forces
                Spindle
                Axis

                          Centrifugal
                          Force

                          Net Spindle
                            Torque

     Hydrodynamic         ASTERN
          Lift




    Hub
  Rotation


  Rolls-Royce
CPP Hub




  Rolls-Royce
CPP System Modifications
Port Engine    Main Switchboard        Stbd Engine




      Port CPP                       Stbd CPP
   Hydraulic Pumps                Hydraulic Pumps
Consequences of Modifications




   Stbd Propeller   Port Propeller
Astern Travel Summary
• Causes
  – CPP pump modifications affected system
    redundancy
  – Astern travel resulted from electrical
    power loss
  – Engines were still turning propeller shafts
• Stopping astern travel
  – No means to control blade pitch
  – Crew could have secured engines to stop
    shaft

								
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