This department is responsible for all measurement surveys throughout the yard for both naval and commercial ships. Current NNS projects include: two new aircraft carriers, one carrier overhaul, the new attack submarine (joint with General Dynamics' Electric Boat), and three Double Eagle oil tankers for delivery to Eletson Holdings of Piraeus, Greece. An additional five Double Eagle tankers for delivery to HVID Van Ommeran of Florida and one tanker has already been delivered to Mobil Oil Company.
During construction of the Double Eagle, hull segments of approximately 50' (16 m) in length are assembled, then transported to a final platen where they are assembled into a grand block. The grand block is then erected in the dry dock by the yard's 900 ton crane. A typical hull segment is comprised of the horizontal keel section, and one port and one starboard side shell section. All three sections are initially fabricated in the horizontal position, then the vertical sections are rotated 90 degrees before being welded to the horizontal keel. The measurement group targets all three sections during fabrication. When the three sections are ready to be joined to form a grand block, the measurement team monitors the port and starboard sections for parallelism to each other, deflection and perpendicularity to the keel section.
Conventional methods require to trim the excess material during the joining. This is very much time consuming, as it practically ties up both production facilities and schedule (e.g. the crane time). One of the biggest benefits in using the Leica 3D Dimensional Control System is as follows: Each section is measured on-site in order to pre-calculate the burning map of the excess material. The goal is to trim each section accordingly prior to the joining process in the critical path. The benefit: The section is joined without any rework and it fits immediately. The critical path is reduced, production facilities have less down-time and the production process is speeded up.
Newport News Shipbuilding, with its three STM systems, is in an optimal position to take advantage of the new Axyz Software. Currently, the NNS survey group will be able to "shoot" simultaneous jobs using Axyz' multiple "measurement windows" capability and will be able to measure targets on both sides of a hull segment simultaneously. With the planned addition of MTM, the survey team will be able to eliminate the need to transform two surveys of the same hull segment together via common points. Additionally, MTM will allow the shipyard to use the TDM5000 instruments in conjunction with their existing T2002 instruments. The shipbuilders are quite impressed with Axyz STM. Additional seats of Axyz CDM are planned for installation around the shipyard to analyze data after collection.
Since much time is spent by Ron Hicks' team in analyzing data once it is collected, another integrated Leica software tool which NNS will be using is the DCP20/30 shipbuilding software package from A.M.S., Finland. Newport News have started using DCP20 in September, 1997 for accuracy control applications.
Leica is very excited about the opportunity to work with NNS and looks forward to both parties learning and profiting from the relationship. Anchors away!
