Silkap · video

What this video covers

Sailing the Tuamotu atolls with OpenCPN and MBTiles satellite imagery, Ivo explains how coral heads (patates) make standard chart data nearly useless and why satellite images are the practical substitute.0:35 Navionics, C-MAP, and other conventional charts cover only atoll passes at best; no standard chart plots individual coral heads inside a lagoon. MBTiles satellite layers, sourced from Google, Bing, and ArcGIS, show both exposed coral heads as white dots and submerged ones as darker patches — some as shallow as one metre. Ivo and Dajana sail at 3 knots under sail rather than motoring, keeping a one-mile zoom on OpenCPN so they have time to alter course before reaching the next hazard. The same imagery identifies sand patches for anchoring and reveals whether a motu provides wind shelter — demonstrated at Makemo (sand patch found amid surrounding coral) and Raroya (anchored behind a motu against a south-east marameau). Four download sources are named: Chartlocker, Soji Paus, SV Oslot (also carries C-MAP and Navionics tiles), and Amazing Grace (Mediterranean only). Compatible software includes OpenCPN, QVTLM, and the free Android app Guru Maps. A live GPS feed is required to navigate rather than just browse the images. The system was first used in the San Blas archipelago, Panama, and has since allowed a midnight atoll entry without incident.

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