Save a region for offline — the chart and the routing data, in one download

Download a region once and it carries both halves: the chart you see, and the routing data auto-route plans with. See the size before you tap, watch the percent, pause and resume.

Chart drawer → Offline Charts lists NOAA's chart regions. Each region is one download carrying two things:

• The chart picture — NOAA's chart as you see it on the map, so it draws with no signal.
• The routing data — what auto-route plans with: charted depths and NOAA's detailed charts, dredged channels and the Corps of Engineers' maintained channels, charted land, wrecks, rocks and obstructions, bridges and overhead cables, channel markers and traffic schemes. It is saved only for the region's charted water, not the land or the open ocean inside its box.

With both on this phone the chart draws, auto-route plans, channel markers show, and your saved routes are re-checked against the charts, all with no signal. With no signal, auto-route also uses every detailed chart square this phone has pulled before, however old: the newest chart it has. Where a stretch of open coast is charted only at coastal scale, the deep water a saved region proved still counts when auto-route plans a short run across it.

The routing data is the slow half: it comes from NOAA a square at a time, so a large region can take a while. Keep theONE open while it saves; it carries on where it stopped next time you open the app.

Steps

1. See the size first

   Each region shows about how much it will take before you tap Download — the chart picture plus the routing data — and the top of the screen shows how much space is free on this phone. A region that will not fit says so and stays off.

2. Download, and watch the percent

   Tap Download. One bar and one percent cover both halves, with about how much is still to come. One region saves at a time; a second you tap waits in line and says which region it is waiting for.

3. Pause and Resume

   Pause stops where it is. Nothing already saved is lost, and Resume carries on from there — the chart picture from the byte it stopped at, the routing data from the next square. If the signal drops, the save pauses by itself and carries on when the signal is back.

4. Cancel or Remove

   Cancel stops a save; squares already saved stay. Remove takes a saved region off this phone — the chart picture and its routing data — after asking first. Water you painted, and squares another saved region shares, stay.

5. Paint your own water

   For water that is not a whole region, Paint water: drag along the water you run. It shows how many squares and about how much before you download, then the same percent and Pause.

Related

• Where your data lives — and the one thing that does leaveUntil you sign in, everything you enter stays on this device. Your position goes out to fetch weather, tides and charts, and to Apple to name the place you are. Here is exactly what leaves, and when.
• Chart layers — GPS, channel markers, weather radar, buoys, depths, track lineToggle the six chart overlays — GPS position, channel markers (AtoN buoys and beacons from NOAA), NEXRAD weather radar, NOAA weather buoys, depths (where the auto-router will and won't take your boat) and the track line — and start a cruising track from the Track line row.
• Route Editor — draw, edit, and reorder waypointsPlot a route on the chart by tapping waypoints, then move, insert, delete, or reorder them.

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