Seafreeze America

USNS John McDonnell (T-AGS-51) was a hydrographic survey ship operated by the Military Sealift Command (MSC) with a contract crew for the Naval Oceanographic Office which assigned a military and civilian hydrographic detachment to conduct coastal surveys. The ship and its sister, USNS Littlehales (T-AGS-52), were replacements for the coastal hydrographic survey vessels USNS Chauvenet (T-AGS-29) and USNS Harkness (T-AGS-32). The keel was laid by Halter Marine, Inc. of Moss Point, Mississippi on 3 August 1989. Launch took place on 13 December 1990 with the wife of the ship's namesake, Mrs. Mary McDonnell, as sponsor. On 15 November 1991 John McDonnell was placed in service with MSC. The new vessels were about half the length of those large survey ships with two rather than four survey launches. Contract crew size was 24 instead of 70 for the larger ships and the military and Naval Oceanographic Office civilian hydrographic detachment could be decreased from 80 to 10. With reliance on the Global Positioning System (GPS) for navigation and modern multibeam shallow-water sonar (SIMRAD EM100) and updated computer hardware and software for data processing the ships were expected to operate 24 hours a day, seven days a week collecting more soundings per mile than the older ships in coastal areas at depths up to 600 m (328 fathoms; 1,969 ft).