Stability and Flooding

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Stability and Flooding

• Eric Stolzenberg

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Presentation Overview

• Stability
• Flooding progression
• Impact of physical rudder loss
• Effects of astern travel

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Vessel Configuration
Fishing Vessel Alaska Ranger
OSV Ranger
Wheelhouse
Focsle Deck
Trawl Deck
Factory Deck
Ramp
Freezers
Processing Area
Machinery Spaces
Hold
Rudder
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Stability

• Stability criteria
• Intact stability capsizing
• Damage stability flooding
• Stability requirements
• Necessary for vessel certification
• Incorporate stability criteria

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Vessel Intact Stability

• Owner monitored stability
• Not required
• Intact stability through TS booklet
• Damage stability not monitored or required
• Postaccident Coast Guard MSC review
• Stability test confirmed
• TS booklet met requirements
• Intact stability met requirements

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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

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Flooding Progression
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Flooding Progression Profile
Aft Fish Bin (Freezer)
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Flooding Progression Plan
Watertight Bulkheads
Watertight Bulkhead
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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

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Rudder
Lock Nut
Thrust Bearing
Hull
Starboard Rudder
Upper Rudder Assembly
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Vessel Traveling Astern

• Exacerbated flooding
• Increased rate
• Decreased distance to downflooding points
• Increased pressure on hatches and doors
• Prevented crew from entering liferafts

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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

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Propulsion System

• Eric Stolzenberg

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Presentation Overview

• Causes of astern travel
• Propulsion system overview
• Propulsion system modification
• Means to stop travel

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CPP System Overview
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Propulsion System Layout
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Spindle Torque Forces
Spindle Axis
Centrifugal Force
Net Spindle Torque
Hydrodynamic Lift
ASTERN
Hub Rotation
Rolls-Royce
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CPP Hub
Rolls-Royce
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CPP System Modifications
Main Switchboard
Stbd CPP Hydraulic Pumps
Port CPP Hydraulic Pumps
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Consequences of Modifications
Port Propeller
Stbd Propeller
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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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