# Rounding Directions and Waypoints

eStela uses three types of marks to define race courses:

* Rounding Buoys
* Waypoints
* Doors

Each type has a specific role in tracking, visualization, and race analytics.

### Rounding Buoys

Rounding buoys are physical marks that boats are required to round. eStela automatically detects whether a boat rounds the buoy correctly based on direction.

* The **system calculates the rounding direction automatically** based on the previous and next mark in the course.
* If the angle between the approach and departure is narrow, both directions are accepted.
* You cannot manually set the rounding direction.
* These marks are included in:
  * Time tables
  * Boat performance analytics

Use rounding buoys to define required rounding points in the race.

### Waypoints

Waypoints are virtual marks that boats are not expected to round. They are mainly used for visualization and distance calculation.

* Waypoints help shape the course for metrics like total distance
* Boats do not need to cross or round them
* They are not shown in time tables or performance metrics
* They cannot be selected during replay or live visualization

Waypoints are especially useful for coastal or offshore courses, where visualizing the intended route is helpful, even if some points aren’t actual rounding marks.

### Doors

Doors are imaginary lines created between two marks. A door is considered crossed when a boat sails through the line in the correct direction, which is also automatically calculated based on the course flow.

* Commonly used for:
  * Start lines
  * Finish lines
  * Mid-course gates (e.g. in windward-leeward layouts)

Like rounding buoys, door crossings contribute to timing and classification features.


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