Safety tab — watch, grounding, approach, distress

Four safety monitors gathered in one tab: a deadman watchkeeping alarm, real-time grounding detection with an escape window, a visual coastal-approach planner, and a VHF DSC distress alert.

Where to find it

Sidebar › Safety (shield icon).

The panel header reads Safety monitors with the subtitle "Watch alarm · grounding escape · coastal approach · VHF DSC". Below it, a bar of four sub-tabs switches between the functions. A pulsing red dot appears on a sub-tab when its function is in alert (watch in pre-alarm/alarm, grounding suspected, or an active approach plan).

Each sub-tab opens with a How to use link (info icon): click to expand contextual help, then Hide help to collapse it.

Hierarchy

Sidebar
└── Safety
    ├── Watch alarm   (deadman watchkeeping, periodic acknowledge)
    ├── Grounding     (real-time detection + refloat window)
    ├── Approach      (coastal approach plan: amers, transits, lights)
    └── Distress      (VHF DSC SOS, position sharing)

Watch alarm

Watchkeeping alarm

What it does: a deadman timer for night passages or single-handed sailing. You must acknowledge at a regular interval to confirm you are awake and able. If you miss the check-in, the alarm escalates (soft beep → full siren) and can optionally auto-trigger a man-overboard (MOB).

How to use it: 1. Set the Interval (min) field (1 to 60 minutes; e.g. 10 min). 2. Optionally tick Auto-trigger MOB on timeout. 3. Click Arm. The state moves from Idle to Armed (green badge) and the Next check-in countdown starts. 4. Before the countdown ends, tap the large Tap to acknowledge button: the timer restarts for a fresh interval. 5. To stop monitoring, click Disarm.

Options & settings:

Possible phases: Idle → Armed → Pre-alarm (overdue, soft beep) → Alarm (siren, flashing red button) → Triggered (auto-MOB fired, message "check MOB panel").

Tips & limits: - Acknowledge as soon as the button appears: in the Alarm phase the button turns red and flashes to grab attention. - Pick a realistic single-handed interval (often 10 to 20 min). Too short and you'll be woken constantly; too long and the safety value drops. - Auto-MOB assumes a position is available (instruments / GPS). Check the MOB panel afterwards.

Grounding

Grounding escape

What it does: detects in real time when the boat goes stationary (the keel is about to touch or has touched bottom) and, when triggered, computes a refloat window from the tide, accounting for your keel draft and a safety margin.

How to use it: 1. Tick Enable automatic detection. 2. Set the Safety margin (slider 0 to 1 m) for the under-keel caution you want. 3. Let the app monitor speed over ground (SOG). While all is well, the status shows "Monitoring SOG" or "Stationary {n}s". 4. If grounding is suspected, the panel turns red ("Grounding suspected"). The app then computes the tide window: current tide, required height, Refloat at time, window end and duration. 5. Use Refresh plan (cycle icon) to recompute as conditions change, or Dismiss (cross) once clear.

Options & settings:

Information shown during alert: Current tide (with rising/falling arrow), Required, the reminder "Keel {x}m + margin {y}m", Refloat window (refloat time, end, duration) and Next high tide. If the tide is insufficient, "No tide window within 24h" appears with advice to await the next spring tide or call for assistance.

Configure the keel depth (prerequisite): 1. Open the sidebar › Conf. 2. Engine & Fuel section. 3. Enter Keel depth (m) (e.g. 1.8). This value feeds the under-keel clearance and grounding detection. 4. Click Save.

Tips & limits: - Detection and the window calculation require a connected depth sensor (SignalK) and a keel draft configured in Settings. - The refloat window comes from tide prediction: it is an aid, not a guarantee. Watch the real water under the keel. - If no window appears within 24 h, tide alone won't lift you: consider a later spring tide or assistance.

Approach

Coastal Approach

What it does: a visual-piloting aid for night or poor-visibility approaches. From a point clicked on the chart, the tool extracts SHOM amers, lights and beacons plus Sea-Seek harbours within a chosen radius, then computes transits (two amers on the same bearing), leading lights, and clearing lines (±8° safety arcs).

How to use it: 1. Click the ON button in the card header (it toggles from OFF to ON). 2. Click a point on the chart near your destination ("Click the map near your destination to pick an approach target"). 3. The plan appears: target name (or coordinates), number of Amers, Transits and Leading lights. 4. Adjust the Radius (slider 1 to 15 NM) to widen or tighten the analysis area. 5. Browse the Top alignments list: click a row to centre the chart on that transit.

Options & settings:

Counters shown: Amers (notable marks found), Transits (pairs on the same bearing), Leading (leading-light pairs).

Tips & limits: - This is a heuristic tool: always validate transits and clearing lines against the official chart before committing to an approach. - A transit tagged Leading lights (green background) is usable at night; the others are daytime visual marks. - Usefulness depends on the density of SHOM lights/beacons and Sea-Seek harbours in the area: some regions are better covered than others.

Distress

VHF DSC distress

What it does: sends a real DSC distress alert (Digital Selective Calling) to your VHF over a USB-serial cable (Web Serial), which then broadcasts it on channel 70. The app transmits the NMEA 0183 sentences $GPRMC + $CDDSC + $CDDSE (position, 10-digit DSC code, nature, vessel) three times per ITU-R M.541 guidance.

How to use it: 1. Connect a USB-serial cable between the computer and the VHF NMEA 0183 input port (e.g. ICOM M506/M605, Standard Horizon GX2400/Matrix, Lowrance Link). 2. Enter your MMSI (9 digits) and Vessel name — they are stored locally. 3. Choose the Baud rate (4800 NMEA 0183 by default, 9600 or 38400 HS) and the Nature of distress. 4. Click Connect VHF and pick the serial port. The badge turns Online (green). 5. Check the position is shown (otherwise configure SignalK or GPS first). 6. Hold the SOS button for 3 seconds: a progress bar fills, then the alert fires.

Options & settings:

Tips & limits: - This feature requires Chrome or Edge on desktop (Web Serial). In any other browser the message "Web Serial not supported" appears. - The SOS button stays disabled until the VHF is connected, the MMSI is valid, and a position is known. - SAFETY: this emits a real DSC alert. Only press when genuinely in distress — a false alert is a criminal offence in most jurisdictions.

See also

• Getting started