Garmin GPSTC Datafield - to complement the Motion Simple Logger

Since I have been spending more time inside than normal I have started work on writing a Datafield for my Garmin Fenix 3 to display the categories that we post to GPSTC. I feel this would be a useful addition to those of us who have an approved GPS on the shoulder and a Garmin on the wrist. It would be a nice match for the new "No display" Motion Simple Logger
I know there are some datafields already available, I have been using several for years, the biggest problem I find with them is that the fonts are too small to read without glasses. I aim to maximize the font size wherever possible. Ideally I would like to display all 6 categories in real time, but I have my doubts that I have the processing power to do the alpha 500.
Now I am not a computer programmer. The whole process has been a real battle. Progress has been slow and frustrating, but I am starting to get some results.
I am working on the two screens in the picture. They are fairly self explanatory, the coloured bars show how close your best 5 ten second runs are. At the top of the second screen the approx GPS signal quality is displayed and at the bottom the time of the session.
I have run into many problems, one unresolved issue is the different screens and fonts all the different Garmin watches support. The more detail I put on a screen the more incompatible the graphics appear on different watches.
So this is a call out to those who may be interested. What models of Garmin watch should I support? So far I am working on Fenix 3 and Fenix 5.

For those who are not aware Garmin Datafields can be downloaded for free from the Garmin IQ store and installed on most Garmin wathces. Don't look for this yet though as it is not yet published.
I feel I have to add that this is an on the water tool only, the results are not approved for posting to GPSTC. If you want to argue about that then please do it somewhere else.

Inside time well spent Andrew, looks great! Id love to try it too when you can make it available, Fenix 6s

Great work. I've got a Motion logger coming and use a Garmin FR920XT for on the water feedback. If I can upgrade to a Fenix, I'll be keen to load your Datafield

That screen is looking great Andrew, thank you!

I see in the IQ app store for my Fenix 5, there you find an app called "Windsurf".
Not sure what it really does or how it works? Just wondering what may already be out there working for the majority of Garmin watches with GPS function, as Garmin has been around for long and so has windsurfing?

After a few initial issues, I have rebuilt the datadfields yet again and published new versions on Garmin IQ.
They are now available for download. Simply search for "GPSTC"
Thanks to Russel (rww) for helping me test on the Fenix 5 this morning.

Got it onto my watch no problems and a lap round the block on my bike to see what it showed, the data fields all looking to working fine, thanks very much for doing this Andrew

ps the watch was beeping away at me as I was cycling, Ive just checked the alerts settings for this activity and no alerts set, maybe its an issue in my general settings.

Gave it a bit more of a workout this morning on the foil. Worked great with all indicators pretty close to what appeared on KA72. The 2 sec read a bit low on the watch but this was always a common ocurrance with the Fin151 data fields. Loving the PB beep! Listening for it during the faster runs.

The next logical step is to try and code the alpha 500. This is far more difficult as all the other categories can be derived from distance travelled and speed. In order to calculate the alpha the position of each point needs to be recorded and the distance between the current point and all the recent points needs to be calculated every second.
The first problem is to try and define what an alpha actually is? We all know what it is but defining it exactly in code raises a few questions. How long is an alpha 500? I think KA72 defines it has a gybe with a length of 100 to 500 metres, in reality all the best gybes are very close to 500m. But I thought I should try and measure them all although this does mean more processing.
Then I thought it would be nice to also measure all those gybes that do not quite get back to inside the 50m circle. So I am thinking of something like this:


A page with two columns for Best of session and last alpha, then three rows showing the best 50 metre alpha, the best 60m alpha and the best 70 metre alpha. The 60 and 70 could be user configurable. As the example shows the higher radius alpha will produce faster speeds.
So when practicing alphas the user would be able see if those alphas that just missed out on the 50m radius, which I think would be interesting.

In testing I am comparing the results to the gybes measured on the "Motion". I think the "Motion" may only be recording 500m alphas. Does anybody know for sure?

I would love to roll the three into one app, but my current skills do not allow this. Apparently I would need to do all the code for FIT logging, timing, start, stop, lap etc etc.
So I am combining the alpha into Datafield 1. It will switch between displays depending on certain things yet to be decided. I only have a fenix 3 which will not support this new field due to 16k limit on Datafields, so I have no way of testing it except on the simlator.

I wouldn't mind getting something to replace the GW60, which is sure to die or fall off my wrist soon. I'm just not sure that comparing the results with the above watches against KA72 makes sense. Doesn't KA72 just analyse and summarize data out of the watch? Wouldn't it be better to compare to data from GW60 or GT31?