FS Cheat Sheet 2026

The 30 highest-yield FS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the standard chart datum for US nautical charts and hydrographic surveys? → Mean Lower Low Water (MLLW)
2. A conformal map projection is specifically designed to preserve which of the following properties at any given point? → Local angles and shapes of small features.
3. Which reading is the correct reading for the staff illustrated? → 1.50 m
4. What organization publishes official nautical charts for US coastal waters? → NOAA Office of Coast Survey
5. In the context of processing LiDAR data, which of the following BEST describes the process of creating a "bare-earth" digital elevation model (DEM)? → Classifying and filtering out points that represent vegetation and buildings.
6. What is the purpose of tide gauge readings during a hydrographic survey? → To reduce soundings to a common chart datum
7. What GNSS constellation is operated by Russia? → GLONASS
8. Which of the following is a term used in traverse surveying? → Theodolite
9. What is a 'shoal' in nautical terminology relevant to hydrographic surveys? → A shallow area of water that is potentially hazardous to navigation
10. At what tidal datum is the shoreline officially defined in US tidal waters? → Mean High Water (MHW)
11. What is the typical horizontal accuracy achievable with static GPS control surveying? → Plus or minus 1 centimeter
12. What is a global coordinate system? → UTM
13. A compound curve in route surveying consists of: → Two or more circular arcs with different radii curving in the same direction
14. Which of the following errors in surveying is classified as a systematic error? → An improperly calibrated steel tape that is consistently 0.02 ft too short.
15. What is the geoid used for in GPS height conversions? → An equipotential surface approximating mean sea level
16. A perpendicular offset is at? → 90 degrees
17. What is airborne LIDAR bathymetry used for in coastal hydrographic mapping? → Mapping shallow water depths using laser pulses from aircraft
18. The arc length (L) of a simple horizontal curve with radius R and central angle Δ expressed in radians is: → L = R × Δ
19. In earthwork terminology, 'swell' refers to: → The increase in volume when in-situ material is excavated and loosened
20. What instrument is primarily used to measure water depth in hydrographic surveying? → Echo sounder (depth sounder)
21. In a GIS, which data model is best suited for representing continuous phenomena like elevation, temperature, or satellite imagery? → Raster
22. What is 'draft' in the context of vessel operations during a hydrographic survey? → The vertical depth of the vessel hull below the waterline
23. The Global Positioning System (GPS) provides its raw positional calculations and coordinates natively referenced to which geodetic reference system? → World Geodetic System 1984 (WGS 84)
24. The K-value for a parabolic vertical curve is defined as: → The length of curve (L) divided by the algebraic difference in grades (A)
25. What is the difference between GPS accuracy and precision? → Accuracy measures closeness to true value; precision measures repeatability
26. What is the carrier wave frequency of the GPS L1 civilian signal? → 1575.42 MHz
27. GPS satellites orbit Earth at approximately what altitude? → 20,200 km
28. What does a contour line represent? → A group of points with the same elevation
29. Which statement is correct for this road cross-section? → Cut and fill section
30. In differential GPS surveying, what is the primary purpose of the base station? → To provide known-position corrections to improve rover accuracy