Measurement of the USS Monitor Propeller Using Structured Light and Coherent Laser Radar Scanning Technologies

Abstract

This presentation and technical paper describes the scanning and processing of data for the recovered propeller of the United States Navy warship USS Monitor. The propeller, designed by inventor John Ericsson, was recovered by the National Oceanic and Atmospheric Administration (NOAA) in 1998 and conserved over the next six years. It is now on display at the Mariners’ Museum in Newport News, Virginia, where it was scanned in place. Two different measurement technologies were employed to meet the goal of high accuracy and high resolution. The coherent laser radar system was used to scan the overall propeller surfaces at a resolution of 3 mm. A structured light scanner was then employed to scan at resolutions down to 12 µm to capture details such as surface features and graffiti etched on one of the blades. The point clouds were then merged to generate an accurate model for dimensional and hydrodynamic analysis. This article provides detail and highlights of the scanning and data-analysis activity. Union Navy turned to constructing a radically different ship, the USS Monitor. John Ericsson, a Swedish-American naval engineer and designer of the Monitor, employed a truly innovative design for the ship that included a revolving gun turret, complete iron construction and a screw propeller. Ericsson and his partners were given 100 days to build his state-of-the-art warship, which was to face the South’s “indestructible” retrofitted Merrimack, rechristened the CSS Virginia. After a su