The approach used to document the USS ARIZONA and its immediate environment was low-tech and labor-intensive. No one had ever attempted a detailed mapping of a 608-foot battleship in water of 6-foot visibility. There were no guidelines to follow and no black-box technology that could significantly help. Photogrammetry was precluded because of the visibility constraints, shallow water and high site relief. High-resolution sonar mapping techniques are still in the early stages of development.
The most valuable assets at the disposal of the research director were a highly experienced team of NPS survey archeologists and illustrators, and other diving personnel from the park and US Navy. The methodology centered around string, clothespins, measuring tapes and a lot of mapping savvy -- ironically, much of that derived from mapping Pueblo Indian sites in the desert. About half a mile of No. 18 nylon string was laid over the ship to establish straight lines in a world of twisted metal. Lines were marked every 10 feet with numbered plastic clips, forming a kind of "cat's cradle" over the site. The cradle with its measurable lines was first plotted on paper and then, laboriously, the shipwreck measurements followed. Simple trilateration techniques related known points on the marked lines to target features on the wreck.
Each evening all the data acquired during the day were copied onto a master set of drawings. Each morning mylar overlays were made of small sections of the drawing and affixed to divers' slates, who returned to the bottom for additional detail. Divers had a list of required measurements, and they would simply fill in the blanks on each dive. On some dives more than 60 measurements were taken by a two person team. Thousands of separate measurements were taken during the four weeks spent in the field. An ordinary plastic protractor was used to record changes in angles of the straight lines.
Responsibility for the planimetric view was given to Jerry Livingston and the elevations (profiles) to Larry Nordby. Farley Watanabe and Mark Senning were assigned to the starboard elevation, while Larry concentrated his own in-water time on the port elevation.
To confirm accuracy of critical points along the gunnel and other features of the badly deformed deck, a local survey crew shot targets with an infrared theodolite, or electronic distance-measuring (EDM) instrument. Divers held the reflective mirrors of the EDM motionless on top of a PVC pole, as the bottom was held in place on the feature to be mapped. This proved to be useful in areas where the pole could be stabilized, but was awkward at other points.
A particularly vexing problem developed over the first few days, when the string baseline calculations on the planimetric view repeatedly indicated the gunnels to be several feet wider apart in the bow than was described in the construction plans. This beam measurement was not a detail that should have been altered on ship modifications. We hoped that the infrared theodolite would correct the disparity. To our surprise, the theodolite confirmed the data gleaned from the strings, indicating the ship had expanded at the explosion point, much like an overpressurized tin can. This buckling had not been evident to the divers underwater, whose visual references were compromised by the visibility.
The hull curvature presented other problems for the elevation views. A diver even one body length away could not see the ship, so it was necessary to hand-measure over curves as if they were on a two-dimensional plane. For our purposes, the ship was divided into 10 sections of 60 feet long by the vertical strings from the cradle, creating 20 individual "frames" to be drawn in two dimensions. This approach had one problem: When the whole vessel was pieced together, the scaled drawing was longer than the actual ship. Consequently, the illustrators had to correct each frame to compensate for the two-dimensional depiction of the ship's curved hull. This correcting process was more pronounced on some frames than others, depending on the curvature of each specific section of hull. This was a point in the project where it was highly advantageous to have mappers experienced in rendering cliff dwellings on Southwestern archeological sites. The irregular, three-dimensional features nestled in curving alcove walls of sandstone cliffs provide similar problems for illustrators.
By the time the assessment project began in 1983, low-cost and self-contained color video systems had become commercially available. One of these units was purchased and put to great use in these field operations. The video was capable of recording at least as much as a diver could see in the limited visibility, and was much easier to use in the harbor environment than standard photographic systems. Still photography does not provide instant feedback to the photographer, whereas the color video had a monitor built into the housing that permitted the operator to see exactly what was coming back in "real time." Tricky photographic problems associated with using artificial light in silty water were also reduced by the supplemental use of video.
Perhaps the greatest advantage of video became apparent in the office in Santa Fe months after the field work was completed. Livingston was able to fill in much detail between known map points on specific features by consulting the video tapes. Besides the assistance this provided in the mapping process, tapes resulting from the survey activities proved to be exceptional tools for education, both at the visitors center and on loan to the electronic media. During the active phase of the project, all Honolulu TV channels carried several minutes of the video returns every night for weeks running, and some segments were broadcast on national television.
In addition to rendering architectural drawings of the hull, the team conducted perimeter searches of the battleship to establish the site's extent, inventory the recognizable artifacts where they lay in the wreckage, and mark their positions on the site's base map. The depth of silt around the perimeter of the site was determined by probing with a PVC rod marked in 1-foot increments. All artifacts were left in place, with the exception of items that presented an unacceptable hazard to the memorial that straddles the ARIZONA and through which 5,000 visitors pass each day. Hazardous material included unexploded shells from the 5-inch guns, sacks of congealed gun powder, and corroded high-pressure air or acetylene bottles that were probably used during the salvage activity. The Navy's Explosive Ordnance Disposal (EOD No. 1) team was stationed nearby, and on several occasions they responded to our request to remove such items while the surveyors gingerly exited the water.
Additional studies of the wreck's natural environment were carried out with much greater intensity in 1986, and the methodology is reported in detail in Chapter IV. Those studies included a detailed analysis of the biomass and corrosive properties of the ship, in addition to silt measurements. The technology included manual probes, sampling containers, oxygen probes and a bathycorrometer, which measures galvanic potential of the metal underneath the biofouling crust.
Perimeter surveys to determine the extent of the wreckage field were accomplished using two modes: side-scan technology and divers. Side-scan sonar passes were run in 1983 and again in 1988 using a Klein 100 KHz. A Mesotech side-scan unit used in sector-scan and polar-scan modes was added in 1988. To augment sonar results, dive teams were deployed to conduct 180-degree sweeps that covered the bottom at least 100 feet from the hull remains. The only items divers found were features already noted by the sonar. These features have been incorporated into the site map.
The ARIZONA (BB 39), a Pennsylvania-class battleship designed for operation in the Pacific, was launched in June 1915. Like most warships, it was built to accomplish specific missions that reflect concepts and strategies operative at the time of design, while later alterations reflect changes in technology and strategies.
The first impression of the ARIZONA is its size -- the vessel is 608 feet long with a beam of 97 feet. The ship was built much bigger than contemporary battleships designed for operation in the Atlantic, which demanded a cruising distance of hundreds of miles, primarily under British, French and German strategies. On the contrary, Pacific operations were conditioned primarily by American and Asian strategies, and required cruising capabilities of thousands of miles. Enormous distances in the Pacific between port facilities, repairs, fueling stations and naval engagements imposed initial design considerations that included speed, reliability, protection, long-range guns, and the ability to carry huge supplies of fuel. Later alterations reinforced one or the other design requirements as a result of changing strategies and technologies balanced against ancient requirements for any seaworthy vessel,
The Naval General Board of 1910 set battleship design parameters for new vessels including the ARIZONA. The ship would have 12 14-inch guns mounted in triple turrets in the main battery, oil-burning engines, "all or nothing" armor, and a speed of 21 knots. Torpedoes and armor-piercing shells were considered the main threats. These specifications would produce some of the fastest long-ranging battleships in the world.
The ARIZONA's armor reflects the interplay between technology, strategy and seaworthy requirements. Armor-piercing shells had to pass through the armor to become armed, and if they passed through ordinary hull or deck plate they would not become armed. Medium armor plate would arm shells, and it offered no protection for the added weight. Only very thick steel plate could offer full protection, hence, the "all or nothing" armor strategy. "All" meant 13.5 inches of steel plate, which is found in areas such as the turrets and armor belt at the water line. If sufficient armor was used all over the vessel topside to thwart armor-piercing shells, the ship would be dangerously unstable. A 3-inch-thick deck was used to ward off most shells and to arm those that passed through. A lower deck was installed of 1.5-inch armor, called the splinter deck, and was sufficient to contain the explosion of shells that passed through the upper deck. The combination provided lightweight, effective protection from most shells.
The ARIZONA underwent a major rebuilding program in 1929-31. Deck armor was increased to 5 inches and an inch was added to the turret tops. The alteration that changed the vessel's appearance was the addition of a steel tank outboard extending from below the turn of the bilge to the top of the armor belt on the side, which is the main deck level. The tank was added to increase torpedo protection. The tank, or torpedo blister, contained an outer void and an inner tank for additional fuel oil. In addition to increased protection from torpedo damage, the blister increased hull displacement, which offset the weight of the added armor, and tripled the ship's cruising range by augmenting fuel capacity. Post-1931 alterations mostly involved upgrade of armament, particularly antiaircraft weapons.
The present appearance of the ARIZONA is a culmination of all the many contributive aspects. The archeological remains are the result of physical changes from alterations during the ship's life, post-attack salvage activates, memorialization and submergence for half a century. A swim over the site starkly reveals these changes and forces a consideration of the history of the vessel and the thinking it represents.
Beginning at the stem of the USS ARIZONA and heading aft, a swimming observer would be struck first with the very sharp lines of the bow. The stem at the hull bottom (forefoot) extends forward of the deck line, creating a bulbous bow form that is covered by silt and not visible to divers. The lines are reminiscent of the iron-clad rams, the precursor of the modern capital ship. The extension is not for ramming, but for additional bow buoyancy and control of the bow wave for efficiency at high speed.
Until reaching the area of heavy damage, which begins to be visible about 40 feet back from the bow around frame 10, the ship does not give the impression of being very large -- the thwartship's dimensions here are less than half those of mid-ship. Damage is slight in this area, the weather or forecastle deck is still in place and various deck fittings, chain, cable and some fairleads are still present. The bull nose is undamaged and both holes are clear of marine growth, much in contrast to the hawse pipes, which are heavily overgrown with marine organisms. The anchors and cable have been removed. The salvage report indicates the anchors were blown clear in the explosion that sunk the ship (Navy salvage record 16 January 1943).
Materials litter the deck. The silt is not very deep and many objects are visible. There are 6-inch chromed pipes laying about that were apparently used to outline the bow during pre-monument memorialization. Steel plates, concrete blocks and a wash basin lie among many unrecognizable metal pieces.
At about 40 to 55 feet aft and 2 feet above the present silt line on the port hull side are rectangular through-hull fittings. Their apparent function, as ascertained from historical photos, is some form of out-board discharge.
Little damage is evident until one runs directly into the flared metal edges of the major blast zone, where jagged metal of the hull sides is twisted forward and out. Here the midship area is a confusion of twisted bulkheads and deck elements. The survey team discovered a number of live 50-caliber antiaircraft rounds inside the ship under the folds of twisted metal. Toward the port side there are badly twisted and deformed hatch coamings, which indicate the main deck level.
The extensive bow damage is the obvious result of a massive explosion that blew outward and upward. Hull plates are splayed out over 20 feet from the ship's sides. The explosion appears to have occurred deep within the ship, with the main force directed upward, which is expected because of the dampening effects of the water surrounding the hull. The forecastle deck and 5-inch thick main deck are gone. The armor belt, which is at the level of the torpedo blister, apparently helped contain the blast and direct it upward. The forward bow spaces, which are not armored, are relatively undamaged.
At 70 feet aft, the torpedo blister begins and becomes the dominant feature on the sides; inspection hatches are visible in the blister top. Much of the hull side from gunnel to torpedo blister has been removed by Navy salvage divers, apparently with torches. The Navy salvage record reports much diver cutting between frames 16-24. Evidently the explosion pushed the hull outward above the armor belt. The salvage records indicate metal overhanging the port hull in this area (Navy salvage record 7 April 1943). Scalloped edges from cutting operations are discernible at many points on the wreck. Where there are discontinuities in the hull, it is usually easy to tell if the cause was the blast or intentional salvage actions.
Extensive salvage operations are recorded in the bow area. The remains of the forecastle deck and main deck were cut away and removed, and mud was pumped out of the area. The salvage log records much cutting on the second and third decks and the forward bulkheads. The magazine explosion clearly damaged the lower deck areas aft as far as the No. 2 turret. Navy salvage divers were unable to enter sections of No. 2 because passageways were blocked with wreckage. The explosion apparently collapsed bulkheads supporting the No. 1 turret, which still remains onsite, and the turret rests 15 feet lower than its original position.
On the port side approximately 80 feet and 112 feet aft of the stem, open cracks visible in the torpedo blister continue below the silt line. These cracks in the sides above the silt probably indicate a major structural failure associated with the magazine explosion. In all probability the inner hull and armor belt are also cracked.
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