How did sailors cross oceans before GPS? By dead reckoning — tracking each leg's heading and speed from a known start. But wind and current push you off course.
Dead ReckoningLive
navigating with drift
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Before GPS, navigators tracked position by dead reckoning: from a known start, add up each leg's heading and speed over time. But wind and current push you off your intended track, so the actual path drifts. The gap between where you meant to go and where you ended up is why sailors and pilots learn to correct for set and drift.
Reading this result: Over 4 h the current carries you 12.0 nm off the intended track; steering a correction angle up-current would cancel most of this set.
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How it works
Dead reckoning estimates position by summing each leg of travel: heading times speed times time, from a known origin. The catch is drift — wind and current carry you sideways, so your actual track diverges from your intended one. Learning to correct for this set and drift is a core skill of marine and air navigation, and the fallback when electronics fail.
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Is this dead reckoning navigation tool really free?▾
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The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.