SALVAGE OF THE SALVAGE OF THE BATTLESHIP BATTLESHIP USS USS UTAHUTAHFOLLOWING THE FOLLOWING THE ATTACK ON PEARL ATTACK ON PEARL HARBORHARBOR19421942--4444USS UTAHUSS UTAH built at Camden, NJ in 1909-10-21,825-ton Florida Class battleship-Served in Atlantic Fleet during World War I-Extensively modernized in 1925-Converted to a radio-controlled target ship in 1931Being downBeing down--graded to a target ship in 1931, the graded to a target ship in 1931, the Utah was not retrofitted with torpedo bilges like Utah was not retrofitted with torpedo bilges like the other older battleships at Pearl Harborthe other older battleships at Pearl HarborJAPANESE ATTACKED JAPANESE ATTACKED NORTHWEST SIDE OF FORD ISLNORTHWEST SIDE OF FORD ISLThe The Utah Utah was was targetedtargetedbecause because she was berthed she was berthed wherewhereaircraft aircraft carriers were carriers were usually tied up on usually tied up on the weekends. She the weekends. She received two received two torpedoes torpedoesThe Utah was situated on the northwest side of Ford Island, where American carriers were usually berthed. Her decks were planked with heavy timbers because she was used as a target ship for the battle fleet. Efforts to prevent her capsizing failed and 58 were killed. Note ensign on fantail which was never fully raised.Captain Homer N. Captain Homer N. WallinWallin, , USN Naval Academy USN Naval Academy Class of 1917 Served Class of 1917 Served initially on battleshipsinitially on battleshipsPost graduate degree in Post graduate degree in Naval Architecture from Naval Architecture from MITMITPrior to Pearl Harbor Prior to Pearl Harbor attack he was the Material attack he was the Material Officer on staff of the Officer on staff of the Commander, Battle Force Commander, Battle Force ––PacificPacificADM ADM NimitzNimitzpromoted him promoted him to Captain and made him to Captain and made him the Fleet Salvage Officer the Fleet Salvage Officer and Salvage and Salvage SuperintendentSuperintendentSituation when salvage beganSituation when salvage began--19421942Salvage efforts concentrated on the least damaged ships first, the Oklahoma and Utah were the last ships to receive serious attention Capsized hull of USS UtahCapsized hull of USS UtahThe Navy contracts with Pacific The Navy contracts with Pacific Bridge Company of San FranciscoBridge Company of San Francisco••Refloating Methods ConsideredRefloating Methods Considered••Sealing the holesSealing the holes••PontoonsPontoons••CounterweightCounterweight••Floating Dry DocksFloating Dry Docks••Power winches on shore and rigging direct to the Power winches on shore and rigging direct to the ship; This technique was previously employed to ship; This technique was previously employed to recover an overturned 19,000 ton caisson during recover an overturned 19,000 ton caisson during construction of the Midconstruction of the Mid--Hudson suspension bridge Hudson suspension bridge at Poughkeepsie, NY in 1930at Poughkeepsie, NY in 1930--3131Subaqueous Materials beneath Subaqueous Materials beneath and around the USS Utahand around the USS UtahCharles H. Lee of San Francisco was retained to determine the soil conditions and predict how the deformed mud would behave as the battleship was rolled overPlan view of Utah hull, viewed from offshore sidePlan view of Utah hull, viewed from offshore sideCross sections through the Utah’s hull to verify Cross sections through the Utah’s hull to verify overturning forces and anchor pull loadsoverturning forces and anchor pull loadsSoil Mechanics TestsSoil Mechanics Tests1. Can sufficient passive resistance be developed under the ship to prevent sliding?2. Recommend methods of stabilizing the soil to prevent sliding.3. Can preliminary dredging be conducted without reducing friction to the point of sliding?4. Will hull sink deeper in 120 and 90 degree positions?5. Asked to perform model tests to confirm the assumed loadsSoil Conditions in Pearl HarborSoil Conditions in Pearl HarborLegendA Soft Grey Clay, Mud or SiltB Soft Grey Clay, Mud or Silt with Coral Fragments, Sand & ShellC Medium Hard Brown ClayD Medium Hard Brown Clay withCoral Fragments, Sand & ShellE Coral Fragments or Sand & Shellsometimes with ClayModeling ResultsModeling ResultsExhaustive tests were conducted on a 1/96 scale model in a tank with soil from San Francisco BaySoil shear testing resultsSoil shear testing resultsLine Pull CalculationsLine Pull CalculationsActual pull was within 5 percent of calculationsSoil mechanics test resultsSoil mechanics test resultsSkin friction in mud= 400lbs/ft2Skin friction in mud= 400lbs/ft2Skin friction in Skin friction in siltysiltysand= 500 lbs/ft2sand= 500 lbs/ft2Concerns for bow slidingConcerns for bow slidingooA max winch pull of 8,000 lbsA max winch pull of 8,000 lbsPassive Soil Pressures Controlled Passive Soil Pressures Controlled the Extraction Methodologythe Extraction MethodologyThe model studies indicated rolling of the riveted hull rather than sliding on the soft bay muds, but there was concerns about frame distortion of the riveted hullFinal design of AFinal design of A--frame attachments frame attachments to the overturned hullsto the overturned hullsSoil from this area had to be progressively removed to allow final rightingcgMud lineHarbor surfaceCable pull 7,200 tonsCg= 23,800 tonsPhysical Factors that had to be Physical Factors that had to be modeledmodeledNaval Architecture Naval Architecture ––ship is not a rigid ship is not a rigid bodybodyConstruction of AConstruction of A--frames, winches and frames, winches and pump systemspump systemsEngineering Engineering ––buoyancy considerationsbuoyancy considerationsSkin friction of hull against harbor floor, Skin friction of hull against harbor floor, whether mud or sand. Soil passive whether mud or sand. Soil passive pressurespressuresMetallurgy of riveted frame and plate hullMetallurgy of riveted frame and plate hullAttempted Righting of the USS UtahFixed shore anchorages with power winchesA-framesWinch DesignWinch Design21 Compound pulleys 21 Compound pulleys 429 ton capacity each429 ton capacity eachMotors had to respond Motors had to respond precisely to individual precisely to individual controlcontrolOperator stationed at Operator stationed at each wincheach winchVariableVariable--voltage drives voltage drives 3“ cable between the 3“ cable between the sheaves and