Geographic Position is important because it allows navigators to

• A. Determine the ship's speed
• B. Compute the magnetic variation
• C. Plot three circular lines of position (LOPs) to fix the ship's position
• D. Determine the depth of water at position

Answer: (C)

Knowing geographic position lets you place the vessel on the chart by using lines of position from independent observations. Each observation defines a locus where you could be; when you plot three circular lines of position around known reference points, their intersections converge on a single point—the ship’s actual location. Using three observations provides a more reliable fix because it cross-checks data and reduces the influence of errors in any one measurement. This is why geographic position is essential for obtaining a precise fix. The other tasks—speed, magnetic variation, and depth—come from other measurements or calculations and aren’t obtained simply from your geographic position.