Lesson 5 - Position Fixing
Overview
Position fixing determines where you are at sea. This is essential because steering inaccuracies, wind, and tidal streams can push you off course.
Single Fix
One of the simplest techniques involves spotting a clear landmark, like a lighthouse or buoy, and matching it to your chart. Ideal for coastal navigation.
Position Line
A position line shows where your boat must lie based on an observation, such as a compass bearing, radar range, or visual transit. Two intersecting lines give an accurate fix.
GPS
GPS uses satellites to pinpoint your location with remarkable accuracy. Systems like dGPS and WAAS correct errors for even greater reliability.
Quick Plotting Techniques
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Range and bearing allow quick fixes.
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Use the "fastest last rule" to prioritize bearings for the most accurate results.
Cross-Track Error (XTE) & Chart Plotters
XTE shows how far off your planned route you’ve drifted. Chart plotters provide real-time updates, making navigation faster and easier.
Traditional Navigation Methods
Techniques like the three-point fix, transits, and depth contours are reliable backups and great for cross-checking GPS data
Transits
Techniques like the three-point fix, transits, and depth contours are reliable backups and great for cross-checking GPS data
Depth Contours
If you’re in shallow water, depth contours can act as position lines when matched to your chart.
