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In addition to collecting depth data, or bathymetric data, Rainier conducts limited shoreline verification. Shoreline verification involves ensuring shoreline is depicted accurately on nautical charts. Features offshore or below Mean Lower Low Water must also be located and documented. These features include reefs, rocks, ledges, wrecks, and cultural features.
Rainier performs "near shore" verification during low tide using singlebeam launches and a skiff. The launches drive along the shoreline and verify existing features through observations and the use of sonar. Positions are taken on new features by the launches or skiff. These features are described using notes, sketches, and digital photographs. Other features, which may not be significant to mariners, but may be of interest to scientists (such as island topography or location of eel grass) are also noted.
For some surveys, Rainier uses LIDAR (LIght Detection And Ranging) surveys for their preliminary shoreline data. Prior to the arrival of the ship in a survey area, a LIDAR airplane is flown over the site. Much like sonar, LIDAR measures the time it takes for a beam of light to be reflected back to its origin and determines the distance the light traveled. The beam emitted from the LIDAR airplane is able to penetrate the surface of the ocean if it is calm and there is good water clarity and the depth of the water can be calculated. LIDAR surveys decrease the amount of time spent on field shoreline acquisition and increase the safety of the surveyors. Hydrographers use the LIDAR data as a guide to their shoreline verification.
If a charted feature is not found, a method of disproving its existence is conducted. This involves searching for the item through singlebeam/multibeam acquisition or diver investigation.
If a higher level of positioning accuracy is desired for a new significant feature (i.e. a new pier), a static survey position is obtained. A static survey is conducted by placing an Ashtech Z-FX receiver atop the feature to determine its position.
