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Learning to Cross the Atlantic With Nothing but a Sextant — Sailing Yabá 293

November 30, 2025 · 21 min · 33K views · Brazilian coast

What this video covers

Ben, sailing on a Colin Archer Polo 34, learns celestial navigation techniques from a solo sailor who recently crossed the Atlantic using only a sextant, a watch set to GMT, and nautical almanacs.1:19 The lesson focuses on determining ship’s midday by measuring the sun’s maximum altitude above the horizon.6:06 To calculate latitude, the navigator records the precise time the sun reaches its peak and applies geometric formulas using data from reference books.6:36 The process requires a clear horizon, a stable platform, and accurate timekeeping to avoid significant position errors.16:16 The video also introduces the Brise sextant, a compact, multi-mirror instrument designed by Sven Irwin for use on small vessels.9:23 Additionally, the encounter provides practical insights into gaff-rigged sailing, including the selection of materials, pulleys, and rigging configurations for two-person crews.19:21 Ben’s initial attempt at a sextant fix resulted in a 13-mile discrepancy compared to his GPS, highlighting the necessity of consistent practice and precise horizon sightings for reliable offshore navigation.18:16

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