Classic Navigation In The Modern World
August 2, 2026 · 54 min · 416 views
What this video covers
Tom Tersey, owner and instructor at Maryland School of Sailing, argues that GPS dependency has made modern sailors blind to environmental navigation cues that ancient and post-WWII sailors relied on — and explains how to recover those skills.0:53 He covers reading Gulf Stream entry by cobalt-blue water color and temperature change, identifying proximity to land through floating vegetation and bird species, and using cloud formations over islands as position indicators.1:56 For post-WWII techniques, he details dead reckoning with compass, speedometer, and paper chart, explaining why a speedo measures speed through water while GPS measures speed over ground, and why the difference matters for DR plotting.12:38 He explains danger bearings as an imaginary fence between the vessel and a hazard, useful for compensating leeway and current when passing obstructions.10:22 Compass calibration and deviation tables are flagged as neglected but essential steps before any non-electronic passage.11:55 The Beaufort scale gets attention as a practical tool for reading wind speed from sea state rather than instruments.40:55 Tersey advocates mounting the chart plotter at the nav station below rather than on the binnacle, so the helmsman watches the water.31:32 A lightning strike that killed all electronics on a Maryland School of Sailing boat — leaving the crew without depth sounder — illustrates why situational awareness must run parallel to electronic navigation at all times.28:11
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