FS - Fundamentals of Surveying Hydrographic Surveying Flashcards

What is 'draft' in the context of vessel operations during a hydrographic survey?

Answer: The vertical depth of the vessel hull below the waterline

Draft is the vertical distance from the waterline to the lowest point of the vessel, which determines the minimum water depth required for safe navigation.

What is airborne LIDAR bathymetry used for in coastal hydrographic mapping?

Answer: Mapping shallow water depths using laser pulses from aircraft

Airborne LIDAR bathymetry uses green laser pulses that penetrate clear shallow water, allowing depth mapping of coastal areas from aircraft at high survey speeds.

What is a 'shoal' in nautical terminology relevant to hydrographic surveys?

Answer: A shallow area of water that is potentially hazardous to navigation

A shoal is a shallow area where the water bottom is near the surface, posing a potential grounding hazard that hydrographic surveys must accurately map.

What is vessel 'squat' and why does it matter in hydrographic surveys?

Answer: Sinkage of a moving vessel caused by reduced pressure under the hull at speed

Squat is the sinkage effect where a moving vessel draws down deeper into the water due to increased water velocity and reduced pressure under the hull.

At what tidal datum is the shoreline officially defined in US tidal waters?

Answer: Mean High Water (MHW)

In the United States, the shoreline is officially defined at the Mean High Water (MHW) line for tidal waters, which establishes the boundary between public and private tidelands.

What is the primary advantage of integrating GPS with hydrographic surveys?

Answer: It provides precise horizontal positioning for each sounding

GPS provides accurate horizontal positioning for each depth sounding, enabling soundings to be precisely located on nautical charts for safe navigation use.