1. Office of Marine Safety Stability and Flooding Eric Stolzenberg

2. Presentation Overview Stability Flooding progression Impact of physical rudder loss Effects of astern travel

3. Vessel Configuration OSV Ranger Fishing Vessel Alaska Ranger Hold Rudder Machinery Spaces Factory Deck Fo’c’sle Deck Wheelhouse RampFreezersProcessing Area Trawl Deck

4. Stability Stability criteria – Intact stability: capsizing – Damage stability: flooding Stability requirements – Necessary for vessel certification – Incorporate stability criteria

5. 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

6. 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

7. Flooding Progression

8. Flooding Progression — Profile Aft Fish Bin (Freezer)

9. Flooding Progression — Plan Watertight Bulkhead Watertight Bulkheads

10. 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

11. Rudder Upper Rudder Assembly Lock Nut Starboard Rudder Hull Thrust Bearing Rudder Stock

12. Vessel Traveling Astern Exacerbated flooding – Increased rate – Decreased distance to downflooding points – Increased pressure on hatches and doors Prevented crew from entering liferafts

13. 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

15. Office of Marine Safety Propulsion System Eric Stolzenberg

16. Presentation Overview Causes of astern travel Propulsion system overview Propulsion system modification Means to stop travel

17. CPP System Overview

18. Propulsion System Layout Port main engine Stbd main engine Gear Propulsion Shaft Propeller Hydraulic pumps Main Switchboard

19. Spindle Torque Forces Hydrodynamic Lift Centrifugal Force Hub Rotation Spindle Axis Net Spindle Torque ASTERN Rolls-Royce

20. CPP Hub Rolls-Royce

21. CPP System Modifications Main Switchboard Stbd CPP Hydraulic Pumps Port CPP Hydraulic Pumps Stbd EnginePort Engine

22. Consequences of Modifications Port PropellerStbd Propeller

23. 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