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Depth & soundings — the depth chip on Mission Control

Read the depth tile, keep soundings honest, and know the depth rules the route planner uses.

The Depth tile on Mission Control holds the latest depth reading. It comes off the boat's network and nowhere else — there is no hand entry for depth.

Separate from the tile: when auto-route plans a leg, it works from charted depths and your vessel's minimum operating depth. By default that is calculated — 1.5 × draft plus a 2 ft safety margin, so a 6 ft draft gives an 11 ft floor. Water the chart cannot prove is at least that deep is treated as impassable. Unknown depth never counts as safe.

Both halves of that are yours to change, in Vessel Setup → Vessel Details. You can set your own safety margin — 0 ft, 5 ft, whatever you run — and the floor keeps following draft as she changes. Or you can switch the calculation off and hold to one fixed figure.

Steps

  1. Read only

    The Depth tile sits on Mission Control's telemetry strip and shows the latest reading off the sounder. It does not open anything — there is no depth history page and no way to type a sounding in by hand; the manual telemetry sheet deliberately leaves depth alone, and the depth field in a logbook entry belongs to that entry, not to this tile.

  2. The same goes for the engine and battery tiles

    Engine temperature shows —°F until an engine actually reports one, and House batt shows — % with "No reading yet" instead of a percentage and a charge state.

    The invented number was bad; the invented charge state beside it was worse, because it described a condition nobody had measured.

    The bank VOLTS on that same tile had been honest about this for months. The percentage simply never got the same treatment.

  3. A dash means no reading — it does not mean zero

    Depth and Heading show — when nothing has reported one: no sounder or compass on the network, the bridge disconnected, or, for Heading, nothing entered by hand yet. A dash is theONE telling you it does not know.

    Zero feet under the keel is aground and 000° is due north, so a boat with no sounder and no compass could sit at the dock reporting a grounding on a northerly heading.

    One reading did not change: a genuine 000° still reads 000°. Telling those two apart is exactly what the dash buys you.

  4. What theONE does and does not watch

    Depth is live when a sounder is on the network (PGN 128267, or DBT/DPT on NMEA 0183).

    THERE IS NO FIXED SHALLOW-WATER ALARM — nothing you can set to 'warn me under 8 feet'. Keep your helm sounder's alarm set; it is the one that does that job.

    BUT TWO THINGS DO WATCH:

    • WATER SHOALING. With a gateway connected, theONE measures how fast the bottom is coming up and warns you when it rises 6 feet a minute or faster while you are making 3 knots or more. A rate, not a depth — it catches a bank you are running onto, and says nothing about anchoring in six feet.
    • DEPTH MARGIN BREACH. While a leg is in progress or paused, opening its route with Plot on chart probes the charted depths along it, and theONE sends one notification if the shallowest charted depth is less than your draft plus that leg's operating depth margin. It fires once for that leg engagement — counted once iOS accepts it: with notifications off it tries again at the next check, and Plot on chart says under its depth chip that the alarm could not notify you. That one comes off the chart, not the sounder. Where the chart gives an area's depth as a range — 6 to 12 feet, say — theONE reads the 6, the shallower figure, here and for the red pins and red legs in the route editor. Auto-route reads a range the same way when it plans through charted channels and fairways. And when the probe along a route finds no charted depth anywhere on it, the editor says Depth warnings unavailable rather than showing nothing — silence is never a clean bill.

  5. Where the charted depth comes from

    The shallow-water marks in the route editor — a red pin with a warning triangle, a red leg drawn wider and dashed — and the depth margin breach above, read charted depth from NOAA's electronic navigational charts (ENC) — the same charts auto-route plans from. theONE asks the most detailed chart that covers the spot first — harbour, then approach, then coastal, then general — and takes the shallowest depth area it finds there. If NOAA cannot be reached, the editor says Depth warnings unavailable; it never guesses a depth.

    theONE is for situational awareness. It supplements — never replaces — good seamanship, official NOAA charts, your own sounder, and the U.S. Coast Guard's notices and guidance.

  6. Your depth floor, and the two ways to set it

    Vessel Setup → Vessel Details → Navigation defaults.

    CALCULATED (the default). 1.5 × draft plus your safety margin, recalculated whenever draft changes — loaded or light, a new tender on the platform. Change the margin to suit the boat; 0 means bare 1.5 × draft, which is a real choice for a shoal-draft hull.

    FIXED. Switch the calculation off and type one figure. It does not move when draft does, which is the point and also the risk — nothing will remind you it was set for a lighter boat.

    Switching between them keeps both numbers, so you can go back.

  7. Inside a surveyed channel the margin comes off

    A charted dredged area or a maintained reach carries a surveyed depth, so auto-route holds to bare 1.5 × draft there and your safety margin does not apply. That is deliberate: the margin is your open-water cushion, and a channel commercial traffic runs daily is the one place you do not need it. Without this rule the ICW through north Biscayne Bay — charted 9.8 ft — reads as impassable to a 5.4 ft draft.

  8. Feet or meters

    The operating depth chip and its sheet, and the sheet that says why auto-route could not route a leg, read in the length unit you chose under Settings → Account → Measurement units — feet or meters. Draft, margins and depths are kept in feet and converted only for what you read.

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