Besides the current position, Map can draw the path the yacht has taken to get there.
Showing and hiding the track
Click the vessel pin. Along with the details panel, a dashed line appears running from the vessel's earlier positions up to where it is now. Click the pin a second time and the track disappears again.
The track is made of three things:
- Dots — one for each stored earlier position, in the order they were received. The vessel's current position is marked by the pin itself rather than by a dot.
- A dashed line — joining the dots and running on to the pin. It passes exactly through every dot rather than being smoothed, so a sharp corner in the line is a real change of course, not a drawing artefact.
- Arrows — spread along the line, each pointing the way the vessel was travelling on that leg. They are spaced by distance rather than by number of dots, so a long open-water leg always carries an arrow while a cluster of near-stationary positions in a marina does not fill up with them.
How far back the track goes
The track is built from the most recent stored positions for that vessel — up to two hundred of them. There is no date picker and no way to ask for a particular week: you get the last stretch of the vessel's movement and nothing older.
How much time those two hundred positions cover depends entirely on how much AIS data has come in. Positions are not stored every time a transmission arrives; a new one is kept only when at least ten minutes have passed since the last one that was stored. That keeps a moored yacht from filling the track with hundreds of identical dots, and it means the closest spacing you will ever see between two dots is about ten minutes.
If reception has been patchy, the gap between two dots can be hours or days instead. When that happens the line simply runs straight from one dot to the next — a straight leg across a long gap is the app joining two known points, not a record of the route actually sailed.
When no track appears
Clicking the pin shows no track if no earlier positions have been stored for the vessel yet. That is normal for a yacht that has only just been added, or one whose AIS has only been picked up once. The pin and its details panel still work.