This past weekend I finally got to make a controlled experiment to determine the effect (if any :) ) of the Instinct's bearing/course navigation setting, an issue that I thought needed clarification. These are my conclusions. Please consider this a best effort, and take my conclusions with as much salt as you think they require.
My main conclusion is: there is in fact a clear difference between these two modes. However, when navigating a course, the Instinct will always be in “course mode” (which somehow makes sense), irrespective of the bearing/course setting. That is why we could not find a difference between the two modes in this context. The bearing/course setting only comes into play in other types of navigation (I used navigation to a known position). Details are provided below (sorry for the long post), if you want them.
The test course was an open rectangle (start, waypoint1, waypoint2, finish), and the course had, thus, three legs (Start to WP1, WP1 to WP2, WP2 to Finish).
Notes: a. I only tested the behavior of the map screen. b. To simplify the evaluation, I used the map in the “North up” setting, which, IMO, makes things clearer and easier to understand.
Conclusions:
1. The first thing to keep in mind to understand what the watch is telling us, is that the behavior of the two arrows in the map screen depends on whether we are moving or not. If we are moving, their behavior is based on our (GPS-determined) direction of movement. When we stop, however, the watch cannot determine our direction of movement anymore, and therefore the arrows start to rely on the magnetic compass. This means that, when we start/stop moving, the arrows will possibly rotate, because their reference will suddenly change (even though the geometrical situation does not). This may, at first, be a source of confusion, but the confusion disappears once you understand and expect the behavior. Some of you may consider this obvious, but here it is, for completeness.
The small arrow, drawn along the course, in this “North up” setting, shows either the direction in which we are moving (if we are moving) or the direction into which the arrow carved in the watch bezel is pointing (if we are not moving). Therefore, unless the top bezel of the watch is pointing straight ahead of you, the map arrow will rotate when you start/stop moving (a couple of seconds later, in fact).
The arrow in the circle will also behave differently depending on whether we are moving or not. If we are moving, its indications are relative to the direction of movement. For example, if it points to the right (3 o'clock) it means that it wants us to turn 90 degrees to the right, relative to the direction along which we are moving; if it is pointing straight ahead (12 o’clock), it means that it wants us to keep walking straight ahead in the same direction that we have been moving; if it points down (6 o'clock), It means that it wants us to reverse direction, and so on. When we are not moving, the arrow in the circle will point to the direction where we are supposed to go. It is not relative to the direction of movement anymore; it's the absolute direction in which we should move, to go where to watch wants us to go.
2. Following a course. While following a course, the bearing/course setting does not change anything. The watch will always behave as per “course mode.”
While “on course,” the watch will be showing you what you are doing (map arrow) and what you should be doing (circle arrow). You just have to keep in mind how to read the arrows (see above), something that quickly becomes instinctive (pun not intended :) ) once you understand it.
When we go “off course,” the watch will try to determine which is the ”leg” of the course closer to you (with some latency and occasional quirks). Its indications will then be based on that leg. The circle arrow will try to direct you to the waypoint at the end of that course leg (not to the final destination of the course, nor to the closest point of the course). Again, you just have to keep in mind how to read the arrow (see above). The distance that the watch shows is, however, not the distance to that waypoint, but instead the distance to the closer point of the course leg in question. This may seem contradictory (direction to a waypoint, but distance to a different thing), but it is in fact not. It is probably a result of the strong tradition of Garmin with flight instrumentation (namely VOR).
3. Navigating to a known position. In this case, the bearing/course setting comes into play.
In course mode, when we start the navigation activity, a course to the desired location is established (with a proper Start and a proper Finish), and from then on everything behaves as when navigating a course (you can be on course, off course, etc). You will be following a course (albeit a simple one), for all practical purposes.
In bearing mode, no course is established. A line is drawn from your position to the desired destination, with no Start or Finish symbols (but a small flag indicating the destination), and the watch will always direct you to the destination. If you move sideways, the line between you and the destination will be redrawn, so that it will always connect you with the destination. This means, namely, that there never will be an “off course” alarm, because the intended travel path will always accompany you. In fact, there is not an established course; only a dynamically updated solid line that moves with you and is always connecting your current position to the destination. In my opinion, this is also a behavior that makes sense, given that, by choosing the bearing setting, you declared that you did not want to follow a specific course, but only to be advised of the bearing to the destination.
That's all, folks. This experiment was useful to me. I can now sleep in peace J. I can only hope that is may also be useful to some of you.
