Tuesday, November 2, 2004 Matthew A. Russell has been an archeologist with the National Park Service Submerged Resources Center since 1993. He serves as Project Director for the USS Arizona Preservation Project.

The First Day On Site

Red bars indicate the approximate locations of Frames 70 (right) and 90 (left), where ultrasonic thickness testing is being done. Original drawing by Jerry Livingston.

Drilling through the encrustation that covers the ship to get to the bare metal for a reading. NPS photo by Brett Seymour.

As planned, today was our first day of underwater work on USS Arizona.  We left hotel at 7:00 am this morning, but it still took until nearly 11:00 to get in the water – even when you think you’re ready to go, there are still sometimes hours of work to be done.  We loaded gear on the tour boats and hauled it out to the Memorial, while Art brought the NPS Whaler over from Ford Island.  Jay Schraan and Randy Jones from Inspection Technologies spent some time prepping their instruments, while the rest of focused on the myriad other tasks that needed to be completed before we could start diving.  This week is focused on ultrasonic thickness (UT) measurements on 12 strategically chosen locations on Arizona’s hull (see our first update on Sunday for a brief description of what UT measurements are all about).  Brett and I would be make the first couple dives, while Dave Conlin, Don Johnson and Jay and Randy recorded data on the surface.  Since the first area we’re going to do UT testing is directly under the Memorial, today we could stage the work out of one of the rooms in the Memorial and run all our cabling directly to Arizona’s hull.  The locations we’ve chosen for UT testing are noted by “frame numbers” – frames crossed the ship every 4 feet and were used to denote different locations around the ship.  We’re taking UT measurements at frames 70 and 90, on both sides of the ship and in 3 vertical locations at each frame.  This is the middle of the ship, and is the area where we’re developing the Finite Element Model.  Two years ago we took eight hull “coupons” (samples) at frame 80 that allowed us to measure the thickness directly – now we need to expand our hull thickness data, but in a non-destructive manner, so we’ve turned to UT.
 

Taking an ultrasonic thickness reading on the hull.  Photo by Brett Seymour.

The UT process involves using a hole saw attachment for a pneumatic drill and removing a 3-inch diameter disk of the concretion that covers the hull.  We then have to do some surface preparation to smooth an area for the UT probe.  Brett and I traded off using the hammer and chisel to remove some of the most stubborn corrosion products, then a variety of other grinding and abrasive attachments for the drill to get a relatively smooth surface.  The UT probe is connected to the surface by a cable and allows Jay and Randy on the surface to interpret the data, while Don and Dave recorded it.  Brett and I did two long dives where we finished three UT sites (and Brett took these photos), then I was joined by Jeff Woods from the Memorial dive team for a third dive where we finished a fourth UT location.  All in all it was a good start to the project.  Forecast for the rest of the week:  UT measurements galore!

Jar Schraan (left) communicates with the divers while Randy Jones (foreground), Don Johnson and Dave Conlin monitor the unltrasonic thickness readings from the ship. NPS photo by Brett Seymour.