The free global elevation model is coarse in narrow BC inlets. For survey-grade depths use CHS NONNA through the data proxy (Settings).
The curve builds itself as you run at steady speeds.
Fuel remaining is calculated from both engines' SmartCraft fuel-flow readings. Check it against the tank gauge now and then and correct the level if it drifts.
Downloads the area on screen so the chart, depth shading, contours, depth lookups and routing work with no signal. Pan and zoom to your boating area first.
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No depth pack loaded.
Download NONNA-10 as GeoTIFF for your boating area from the CHS NONNA Data Portal (data.chs-shc.ca, free account), then import the .tif files (or the .zip they come in) here. A pack made with nonna_depth_pack.py works too. It gives 10 m depth shading, contours, depth readout and depth-checked routing — all offline. Import more areas any time; they're added to what you have.
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Tide predictions and the last weather forecast are also kept for offline use. To open the app itself with no internet, keep helm_view.html and its lib folder together on the tablet or the Signal K Pi.
Close the Mercury app first — the module takes one connection.
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Live AIS over the internet: get a free API key at aisstream.io (sign in with GitHub → API Keys), paste it below, then Save. On Cloudflare Pages the built-in relay is used automatically.
Not for navigation. Serve this page from the Signal K Pi over http (or enable SSL on Signal K) — an https page can't open a plain ws:// connection.