How sessions are built
How Avelsta automatically splits your logs into sailing sessions: 1 Hz timeline, time at the dock, GPS jumps, split after a 30-minute stop, updates and merges.
The essentials
You don’t need to split your logs: Avelsta builds sessions itself, one per outing.
- All the files of a boat feed a single timeline at one point per second.
- Time at the dock and GPS jumps are detected and set aside.
- Stretches of sailing more than 30 minutes apart become separate sessions.
- Each session gets its statistics, its track and its polar percentage.
Going further
One timeline per boat
Files are not processed in isolation: their points join the boat’s timeline. Two boxes recording the same outing, or overlapping files, therefore give a single session. Importing more files for the same period later updates the session instead of creating another one.
What is set aside
| Mark | Rule |
|---|---|
| Dock | Speed over ground and through water below 0.2 kn, never above 0.5 kn within the surrounding 5 minutes |
| GPS jump | Position more than 10 km from the previous one, less than 10 seconds later |
| Movement too short | Less than 3 minutes of movement, or never above 0.5 kn |
| File too short | Less than 5 minutes of sailing once dock time is removed |
Dock time and GPS jumps stay visible in the timeline but are left out of the statistics, the polar percentage and the track. Each session keeps up to 5 minutes of dock time at the start and at the end.
Splitting between two sessions
A new session starts when more than 30 minutes separate two sailing points. A night at anchor, a stopover or a return to the harbour therefore give two sessions; a 24-hour sail without a stop remains a single session.
Creation, update, merge
At each import, for each block of sailing:
- no existing session over this period: a session is created;
- an existing session overlaps the block: it is updated (status “Updating”, then “Ready”);
- several sessions overlap the block (the new data fills the gap between them): they are merged into the oldest one.
Your manual splits and merges are kept and replayed at each import. See Exclude, split and merge.
A deleted session never comes back
Deleting a session locks its period: importing the same logs again does not recreate it, and data added later over this period is ignored.
Frequently asked questions
Why do my morning race and my afternoon race make a single session?
The boat never stayed more than 30 minutes without sailing between the two (or did not go back to the dock). Use Split here to separate the two races.
Why do some logs give no session?
They only hold time at the dock, or less than 5 minutes of sailing.