Prerequisite: make sure your NMEA stream is properly configured and that you are receiving AIS sentences (they start with AIVDM).

Enable AIS target display

• Open the Settings panel (gear icon, top right).
• Choose AIS.
• Enable Show AIS targets.

Display settings

• Name & speed: show/hide target name and speed (global setting).
  Tip: turn off near the coast when many targets are visible; turn on offshore when few targets are visible.
• Remove lost targets after: time before a target disappears without a received sentence (e.g., 15 min). The target fades out: 100% visibility after a recent sentence down to 0% at the timeout.
• COG vector length: course-over-ground vector length, from 0 to 60 minutes.
• Show target track: global option to display tracks for selected targets or for all targets.
  Tip: “selected” near the coast (many targets), “all” offshore (few targets).
• Track length: Tip: short near the coast (busy areas), long offshore (few targets).

Proximity alarms

• CPA (Closest Point of Approach): minimum distance at closest approach.
• TCPA (Time to CPA): time remaining until CPA.
• Triggering: the alarm triggers when both conditions (CPA and TCPA) are met.
• CPA lines: option to show/hide CPA lines on the chart.

Hide Class B AIS targets

You can hide Class B AIS targets (small recreational boats) to show only Class A (cargo, ferries, etc.)—useful at crowded race starts.

Map interactions

• Icons: green by default. Chevron for Class B, triangle for Class A. Targets in alarm are red.
• Short tap/click on a target: select it and show its track, name (or MMSI if unknown), and average speed over 5 and 20 minutes.
• Long press: detailed panel with:
  • MMSI and Name
  • Navigation status: at anchor, restricted maneuverability, fishing, …
  • Position: latitude & longitude
  • SOG: instant speed over ground; averages over 5 and 20 minutes
  • HDG: heading
  • RNG/BRG: range and bearing
  • CPA/TCPA
  • Crossing: ahead of/behind the target (very useful underway)
  • Position age
  • Static info if available: callsign, type, length, beam, destination

AIS target list

Open the hamburger menu (☰ top left) and choose the AIS tab to display the target list.

For each AIS vessel, the following information is available:

• MMSI and vessel name
• Instant speed
• Speed over ground (5 min)
• Speed over ground (20 min)
• Heading (COG/HDG)
• Range to the vessel
• Bearing
• CPA – Closest Point of Approach
• TCPA – Time to Closest Point of Approach
• At the left of each row, a small color rectangle shows the target state: green if normal, red if an alarm is active.

Sort and filter the AIS target list

To quickly find a vessel, you can sort and filter the AIS target list.

• Sort by:
  • MMSI
  • Name
  • CPA and TCPA
  • Range
  • Instant speed
  • 5-min speed, 20-min speed (popular in racing to monitor competitors)
• Filter by:
  • Name (e.g., type “CHA” to find “Cœur de Chauffe”, “Alyocha”, etc.)
  • Class: type A (Class A) or B (Class B)
  • Status: type “Alarme” or “Alarm” to show only targets with a collision alarm
• Click/Tap a vessel:
  • the map recenters on the vessel and the target is automatically selected.