Structural Assessment of USS Yorktown CV-10
Assessment Team
USS Yorktown History Constructed December 1941- January 1943 Essex Class CV-10 10 th USS Navy Aircraft Carrier Served in WWII Modified in 1955 Served in Vietnam Decommissioned in 1970 Moved to Patriots Point in 1975
USS Yorktown Length: 888-ft (originally 872-ft) Beam (at waterline): 101-ft (originally 93-ft) Draft: 30-ft
USS Yorktown Profile
Assessment Tasks Task 1 - Assessment of Exterior Hull Above the Mud Line Task 2 - Assessment of Exterior Hull Below the Mud Line Based on Literature Task 3 - Assessment of Exterior Hull Below the Mud Line Based on Inspection Task 4 - Visual Assessment of Accessible Compartments in the Bow Region Task 5 - Visual Assessment of all Accessible Compartments in the Remainder of the Vessel Task 6 - Estimation of Rates of Corrosion and Development of Ongoing Maintenance Plan Task 7 - Interpretation of the Structural Assessment and Repair Recommendations
Task 1 Assessment of Exterior Hull Above the Mud Line Galvanic Inspection Level I Dive Inspection of entire hull Level II Dive Inspection at 12 locations Level III Dive Inspection at 12 locations Visual Review from Jon Boat
Exterior Hull Exposure Zones
Task 1 Level II and III Dive Inspection Locations Frame 50 Stern Bow Frame 50
Task 1 Observations
Task 1 Observations
Task 1 Observations
Task 2 Assessment of Exterior Hull Below the Mud Line Based on Literature Literature Survey of below mud line corrosion Review of Task 1 results Review of Galvanic Inspection results Previous Assessment Experience with Similar Vessels Expect to see more significant corrosion in the following areas: o Areas with poor galvanic protection o Interface of mud/water o Interfaces of different soils o Interfaces of different metal types
Task 3- Assessment of Exterior Hull Below the Mud Line Based on Inspection Frame 50 Stern Bow Frame 50 Local, temporary removal of Mud to a Depth of 6 feet to perform: o Level II Dive Inspection at 7 locations o Level III Dive Inspection at 7 locations
Major Findings of Tasks 1 and 3 Task 1 - Tidal & Submerged Zones o Typical layer of marine growth approximately ½ in. thick o Pitting corrosion, typically 1/8 in. to 1 in. diameter o Up to 1/16 in. penetration of pitting corrosion on all areas exposed for inspection o Up to 6.06% loss of section was observed o Average of 2.48% loss of section was observed Task 3 Below the mudline o Pitting corrosion, typically 1/8 in. to 1 in. diameter o Up to 1/16 in. penetration of pitting corrosion on all areas exposed for inspection o Up to 5.60% loss of section was observed o Average of 3.57% loss of section was observed
Tasks 4/5- Visual Assessment of Accessible Compartments from 4 th Deck Down Through Hold Review of accessible compartments at 4 th Deck, 1 st Platform, 2 nd Platform and Hold levels Ultrasonic thickness measurements of exterior hull plate, where accessible Task 4 Forward of Frame 50 Task 5 Aft of Frame 50
Task 4/5 Assessment Areas
Task 4/5 Observations A-504A SD Stores, Frames 19-26 A-504A SD Stores, Frames 19-26 A-605A SD Stores, Frames 18-25 A-605½M Incendiary Bomb Magazine, Frames 18-25
Task 4/5 Observations Chain Locker, Frames 7-12½ A 712T WT Trunk, Frames 50-51
Task 4/5 Observations A 612M Small Arms, Frames 51-55 A 526G Gasoline Pump Room, Frames 58-63 A 620C Damage Control Station, Frames 67-72 A 625C Plotting Room, Frames 74-79
Task 4/5 Observations Forward AMR, Frames 79-86 Forward AMR, Frames 79-86 No. 1 Fire Room, Frames 86-93 C 518E Steering Gear Ram Room, Frames 191½-198
Task 4/5 Observations C 606M 5 Powder Magazine, Frames 155-163 C 610 1AE, Diesel Fire Pump Room, Frames 166-176 C 702E Shaft Alley (Port), Frames 150-161 C 701E Shaft Alley (Stbd), Frames 150-161
Task 4/5 Observations A 403A Electrical Storeroom, Frames 15-19 A 504A SD Stores, Frames 19-26 A 504A SD Stores, Frames 19-26 A-605½M Incendiary Bomb Magazine, Frames 18-25
Task 4/5 Observations A 523M Universal Bomb Storage, Frames 50-58 A 523M Universal Bomb Storage, Frames 50-58 A 523M Universal Bomb Storage, Frames 50-58 A 525½T Bomb Elevator, Frames 55-58
Task 4/5 Observations A 613ET WT Trunk, Frames 49-52 A 523M Universal Bomb Storage, Frames 50-58 A 523M Universal Bomb Storage, Frames 50-58 A 523M Universal Bomb Storage, Frames 50-58
Task 4/5 Observations A 541ET Bomb Elevator, Frames 70-74 B-1-1 Fwd AMR, Frames 79-86 C 610 1AE Diesel Fire Pump Room, Frames 166-176 C 701E Shaft Alley (Stbd), Frames 150-161
Task 4/5 Observations C 516A Vestibule, Frames 184-186 C 605E JP5 Pump Room, Frames 154-163 C 606M 5 Powder Magazine, Frames 155-163 C 607A Air Flask, Frames 163-166
Major Findings of Tasks 4/5 Flooding and/or severe deterioration on 4 th Deck level forward of Frame 19 Flooding and/or severe deterioration on 1 st Platform level forward of Frame 26 and at isolated spaces in forward and aft areas of Task 5 Flooding and/or severe deterioration on 2 nd Platform level forward of Frame 26 and between Frames 38 and 42 and at isolated spaces in forward and aft areas of Task 5 Flooding and/or severe deterioration on Hold level forward of Frame 26 and between Frames 44 and 50 and at isolated spaces in forward engineering flats and isolated compartments in aft areas
4 th Deck Frame 50 Frame 50 1 st Platform Frame 50 Frame 50
2 nd Platform Frame 50 Frame 50 Hold Frame 50 Frame 50
Task 6 Estimation of Rates of Corrosion and Development of Ongoing Maintenance Plan Review all collected data from previous tasks Estimate corrosion rate of hull plate Develop corrosion protection plan Develop ongoing maintenance plan
Task 6 Findings/Recommendations Highest rates of hull plate corrosion found in Splash Zone; approximately.002 to.007 in. loss of section per year Localized areas with 70%-80% loss of section Isolated areas with up to 100% loss of section Rates of hull plate corrosion in tidal & submerged zones found to be approximately.00062 to.0015 in. loss of section per year Regular inspection to ensure watertight integrity of vessel Maintenance of paint and coatings in areas exposed to weather Maintenance of existing Cathodic Protection System to minimize corrosion in submerged areas
Task 7 Interpretation of the Structural Assessment & Repair Recommendations Labor and materials costs to perform structural repairs: Estimated repair costs for deteriorated areas forward of Frame 50: $28,679,541 Estimated repair costs for deteriorated areas aft of Frame 50: $9,809,330 Total estimated repair costs: $38,488,871
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