Fenix 7X Solar - Navigation File Size (or number of track points) for Ultra Marathon

Hi Bluefish,

Yes I read that in the manual but found it very hard to understand how a watch with a 86hr GPS battery life can only do a course which has 200 track points.

I can't see how it would be of any use navigating on a race like TOR330 which has 65,710 track points in the organisers GPX or even a twisty 50Km race. Surely I am missing something?

I don't know if it can be helpful for you: one of my favorite YouTuber and ultrarunner - Wes Plate - has published a video how he splits the official course for "cocodona 250" into sections that make sense for him. He runs with the Enduro 2.

MAPS: Splitting up the Cocodona course

https://m.youtube.com/live/om6Qsp9ddb8?feature=share&cbrd=1 

The 200 limit applies to course points rather than track points. Course points are used for turn directions. User defined course points can also be added such as race checkpoints, aid stations, water sources, and other points of interest on the course. When the number of course points exceeds 200 the watch simply discards any course points in excess of the limit.

A couple of years ago I followed a course during an entire 100 mile trail ultra-marathon on Fenix 6X. I recall that at one point the screen got blank for a long time (perhaps 30-60 seconds). But eventually the watch recovered without me having to do anything. I created that course with a free plotaroute account so I was forced to simplify the course to fewer than 2500 trackpoints. The accuracy was still acceptable with so few trackpoints, however the total distance was shortened by a couple of miles.

Thanks bluefish, That was a very informative video

Thanks silentvoyager, That makes a lot of sense. I can use GPSBabel to reduce the number of trackpoints in my GPX to a much lower number and if necessary split the course into a few course files. I have tried to find a recommended 'limit' for number of trackpoints but don't seem to be able to find one on-line even though this is probably a really important point and my original 14,235 was obviously way too high (it was a downloaded Strava track). I think you mentioned your plotaroute limit of 2500 was a plotaroute limit. Would you have any idea what the safe limit is as you can specify a number of trackpoints in GPSBabel? Or anyone else know?

Really appreciated your response. Thanks

I don't know what a good safe number of track points is. I can look at my other courses. I used plotaroute for a few longer ultras, but I also used courses generated by Garmin Connect, Strava, and Caltopo. However it is unlikely that I ever had significantly more than a few thousand track points because I tend to draw courses from scratch rather than use someone else's GPX files produced from an activity. 

Garmin defines different navigation categories: tracks, routes and courses. 
https://support.garmin.com/en-US/?faq=uJZh4J9rF20RVCRNfCtXV9 
200 points limit applies to courses only. But most of us use tracks for navigation where this limit is not applicable. 
Garmin produces great devices but is also well known for very poor documentation. I couldn't find any limitation figures for the tracks (not routes!) on my Fenix 6X Pro or 7X Pro but I saw a specs for my ancient fenix 3 limiting the number of points for tracks to 10,000.
I finished TOR330 last year with my Fenix 6X Pro. I reduced the original GPX file provided by the orga to slightly below 10,000 points using plotaroute.com. I guess fenix 6X Pro can do more but I wanted to be on the safe side. Then I also added all aid stations and live bases as additional waypoints, again using the plotaroute.com.
Everything went well - I could smoothly navigate all the time and have recorded the entire race (350K with 25,000 meters elevation gain) as a single piece. 
NB: As the data recording type I always use "Smart", not "Every Second". The latter might by slightly more accurate for a fast marathon but absolutely unusable for long mountain races.

Did you feel the 10k points was enough or would recommend loading each one of the sections TorX provides vs using the whole map? Running Tor this year and honestly never thought about the fact I would be maxing out the waypoints. 

Well, loading smaller sections (e.g. 50K between live bases) as well as recording them separately (stopping the watch and saving every section separately) is probably the safest way. But then you can badly estimate your entire progress during the race and afterwards you need some effort to combine all recorded pieces to upload them to Garmin / Strava as the whole.
The original track I got from the TOR orga was about 30,000 points. I guess, my Fenix 6X Pro would have coped with it easily but, to be on the safe side, I've reduced it to slightly below 10,000 (a reference from my ancient Fenix 3), which BTW didn't decrease the track accuracy notably. As said, the navigation and recording of the whole distance worked like a charm for me.
But I believe there are many other factors that may cause a watch crash - too long activity history (I usually delete all saved activities before a race), too many saved tracks (I also delete all of them), active sensors like HRM, Music, Bluetooth, etc. (I deactivate all of them). For long races (100M and above) I also deactivate all GNSS systems but GPS (good enough for Europe) and use Garmin's "Smart" recording, not "Every Second" which is absolutely pointless for long mountain races.