NOAA operates four large ships dedicated to hydrographic surveying: Fairweather, Ferdinand R. Hassler, Rainier, and Thomas Jefferson. Each ship is equipped with the latest echo sounding technology to measure water depth and identify submerged hazards to navigation. The Fairweather, Rainier and Thomas Jefferson also have 2-6 smaller boats (called launches) that are lowered into the water for surveying in shallow areas.
Coast Survey’s research vessel Bay Hydro II, based in the Chesapeake Bay, also conducts surveys. It shares many of the features of the larger ships, and has the additional responsibility to test and evaluate new hydrographic survey technologies.
Coast Survey deploys six navigation response teams equipped with small boats that generally survey port areas. These two- or three-person teams may be moblized from their normal duties to respond to port closures after hurricanes and other emergencies.