Gps-speedsurfing

In many postings over the last 1-2 years Suunto alphas appear mostly (not always, but mostly) faster than the alphas recorded using the standard GT-31. The difference is sometimes as large as 1,5 km/h. Some sailors upload their sessions twice on a given day, once with each device, which puts this difference between the devices nicely on display.
Rumor has it that the Suunto somehow does not take into account the required alpha radius of 50m, and that during upload with specific software, this radius constraint is also not being applied.
If this would be true, it does not maintain a level playing field among sailors, as those systematically posting using the Suunto tend to have a somewhat higher position in the evaluated alpha ranking than sailors using the GT-31.
The evaluated alpha ranking has become more competitive the last 2 years, with more and more sailors competing for a good ranking. Therefore realistic and verifiable results become more important. So it would be nice to have the crew investigate/test/compare the differences between the two devices, in combination with the different upload programs being used, and possibly correct the upload algorithms, to ensure that a level playing field among sailors is maintained.

Please check out our basic rules related to doppler and non-doppler devices. The Suunto is a non-doppler device, and usefull for day-to-day fun-sessions. In our normal rankings this is not a big issue, because more than 95% of the sessions are posted by doppler devices like the GT-31 and GW-60. However in the evaluated ranking system some riders could have some advantage with Max 2s Speeds and Alpha's also. We will have to discuss the within the crew to find a good solution for this. Finding an algorithm to fix this is not so easy we think, because the output of the Suunto watches seems not to be constant in some cases. An other way could be to introduce extra penalty points in the evaulated ranking system for riders with non-doppler devices, please share your ideas about this...

In the alpha ranking there are two sessions posted in the top 25 that are proven not right. One is posted with the GW 60 and the other with the GT31. the leader in the ranking has an alpha of 100 km/h. Both doppler devices. I agree that the suunto has a little higher alpha but also an little lower max speed. But it cannot be stated that the GW60 and the GT31 are without faults and always give the right speed, So it can never be stated that there is an level player field because the GW60 and the GT31 give sometimes proven incorrect alpha values.

Correction on the previous post. Both above mentioned sessions are apparently removed but nevertheless i would still make my point. Removing just these sessions by the gps crew dos not convince me that there are no faults in the registered alpha's with doppler devices because i saw them recently on the site. I cannot imagine the gps crew checks al the sessions posted.

To prove my point, ore better not prove but make it more likely, one more thing.

On November 11 2015 James Battye posts an session at west kirby with an average speed of 54,12 and an alpha of 50.06. He posted this session with a GT31.

I think this is very unlikely. I suppose the gps crew will adapt the alpha of this session also but nevertheless and again. Sure the Suunto is not perfect but i personally saw at least 3 sessions recently on the gps site posted with the doppler devices that are also with faults considering the alpha.

And to come with an solutions and not only sour comments. I think it would be relatively easy to split the ranking in two separe rankings. One with just the doppler devices and the other with non dopler devices.

Thanks Rob for pointing out some GT-31 alpha anomalies.

However, since the GT-31 is the most used GPS (at least since 2012 when I re-entered windsurfing and probably also was for a number of years before), it does seem logical to regard it as the de facto standard measuring device to which other devices are compared and evaluated, especially since such a high % of the riders use it, don't you agree ? Even if we cannot be objectively sure whether the GT-31 is the most accurate measuring device. Someday, in a few years, it will of course be replaced by some other GPS device that will have the biggest market share and gradually have the most sessions posted with, and so will become the new de facto standard, probably with its own specific flaws. But we are not there yet, as the successor GW-60 still is coping with various usability problems, with continually evolving firmware versions, corrections and improvements, so that it will be probably 1-2 years before it stabilizes as a product, attracts more buyers and starts to take on the market share of the GT-31.

Now as to how to solve the discrepancies between the Suunto (non-doppler) and the doppler devices. I have no solution due to my lack of knowledge about GPS theory, can't give another suggestion for the site than the bird's eye view. I am assuming that the geographical data points (positional coordinates - 1 sec or other frequency) are the elementary granular items on which any speed computation is done. So the site could take the data points of the Suunto as they are uploaded, and calculate the best alpha based on the raw data points, using the GPSResults calculation engine (according to the Basic Rules sections this is the engine used).

Difficult to tell as an outsider it this is programmatically possible or even sensible. Maybe not all the data points get uploaded, or maybe they are, but not with all the necessary attributes to do a recalculation. Maybe the integrated GPSResults code base has been stripped down and has no algorithm for computing alphas. Maybe this kind of processing would slow down the uploads too much. Maybe it would even temporarily freeze the entire site as now happens frequently when you click View Track. The crew already hinted at some difficulties surrounding this. So apparently it's not easy to solve technically and maybe this is not the way to go.

I would certainly not go so far as to demand that your postings (and those of others posting with Suunto) would be invalidated or that in the future it should be forbidden to upload using a Suunto or any non-Doppler device for that matter. A handicap or penalty may be a good solution, but than the discussion will become: how much penalty or how to calculate it for any given session, if the uploaded session numbers cannot be compared to another Doppler device...

Therefore, for the sake of fairness, I would just like to encourage you and others, who own a Suunto but also a Doppler device, to post sessions using the Doppler device, not with the Suunto. In that way we will return to a more level playing fields for all riders. I do understand the immediate satisfaction of reaching a personal target, or posting the highest number on any given day. But I am also sure it will give even greater satisfaction, to also reach those numbers on a device that has less tendency to flatter the results.

Dear Pat, I hope this is not an discussion just between the two of us because if it is there is a dutch saying for that. Than we should put up a tree over that at the waterside. ;-)

On the other hand i do not agree with you. A lot of people are complaining about the fact that the Suunto gives a higher Alpha. I hear nobody about the fact that it nearly always gives a little lower 2 seconds peak. You state that we all should use the GT31 because most people are using this device and it has doppler. We alle know that the GT31 is technicaly at the end of it's life. My point was that also the GT31 and the the GW60 can give wrong readings on the site. So you never know if the sessions posted are really right. We asume this is the fact because it's the most used device and has doppler. There are no more investments made in this device. I don't have one anymore because they all died of the lack of waterproofness.

I only have the Suunto and an very expensive Samsung S7 which I rather not use with the GPSLogit app. This on the other hand is a piece of work with the high end processor and the excellent gps. It can see with ease 8 to 10 satelites inside my house. I am not really into rankings but i love to keep sight of my own progressions. For this use the Suunto is excellent. I can see everything while surfing and i am sure it has helped me improve my overall progression a lot the past year. The service of Suunto is very, very good. I had a problem because of fog behind the screen and under warrenty they fixed it within one week. 

We could all buy a Suunto than there is a level playing field again. ;-)

Until the industry launches a new ideal GPS (without the less accurate alpha of the Suunto or the less accurate GW-60 peak speeds), anyone who can not live with this situation is free to enjoy the record-ranking instead of the fun-ranking, I would think?

ZFINS