The topic on the WA speed table and using the 10 sec score has just made me go back through my old data and check some numbers.
For a period I was using a GT 11 and GT 31 in the same aquapack and simply claiming whichever unit gave me the highest 2 sec ( i still do this but am using 2 GT 31's now)
For the particular day I bagged my 2 sec PB i claimed all the numbers off the GT 31 file which gave me a better 2 sec peak by 0.15 of a knot but a slower 5 by 10 by 0.04 of a knot. Now the highest 10 sec from the GT 11 file is 40.063 where as the GT 31 is 39.844.(combining the file spits out a 39.964)
My question is, is it ethical to claim a 10 sec from the GT 11 ( for the purposes of the WA record list) even though I have used the full set of data from the GT31 for the GPSTC and GPSSS sites. The GT 11 's data is perfectly legal just I have not claimed it in the past.
As a secondary question there are a few of us that carry 2 GPS units how does everyone else deal with the data - combine the files, use one unit only for posting or take the best score for each division from each one

Bundy I only have one GPS, a 31. But mate I can't see what's wrong claiming the better result of the two, wouldn't be unethical to me, who knows which one you'd have if you only bought the one unit. And no I wouldn't root around combing files either. Also the WA Table has nothing to do with GPSTC and GPSSS sites and who is going to check anyway

Lao might think differently

But now I'm thinking I might need two as I think mine's reading low

This is a tricky one.

For the GTC at least, we made it pretty clear in the rules that you are responsible for your own data, so in the end it's up to you as to how you handle it.

If it was me I'd do some research as to which was the most accurate method of recording my data, and then use that -- I wouldn't claim the higher number off either device, I'd figure out the 'best guess' as to my speed, and that's what I'd post.

However you won't be penalised for choosing the higher number from your two devices, and you won't even be penalised for using trackpoints (although we recommend that you select "trackpoints" as the calculation method if you do so).

In the end all these numbers are there to track your own progression, and I don't know about you but I'd rather race against a 100% accurate number in the past, rather than one that has been fiddled with in post-processing.

It's completely up to you though

+1 to what Nebs said.
I also sail with 2 or 3 gps most days. Mine are all GT-31's though and any differences are very, very small and I can't remember a time that the differences were larger than the reported error margin without an obvious spike or satellite loss. I always post the complete set from just one GPS though. It is usually swings and roundabouts. One set might give a 0.05 knot faster 2 sec but a 0.04 slower 5 x 10 or Alpha etc. In other words, usually of no practical significance and well within the error margin we might expect from the units themselves (which is exactly as it should be!).
I have seen some funny differences (and usually pretty obvious) between older firmware in the GT-11 and the GT-31 in the Alpha division (comparing Doppler only) but if you have the latest GT-11 firmware, even Alpha differences should be of little consequence.

Do people want me to add whether the file comes from a GT11 or 31 for the ranking?

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lao shi said...

Do people want me to add whether the file comes from a GT11 or 31 for the ranking?

I don't think so, but you should add the date!

As far as carrying two or more 31's, I think it's fair enough to pick the quickest one provided you then use that track for all of the categories.

It wouldn't be reasonable, for example, to take the 2 sec of one unit and the alpha from another.

I am toying with the idea of getting a backup gt31 - purely because I am doing a 1000nm for the British heart foundation and dont want to lose a session. Being a mathematician I would always take the average - but then I am chasing a 30knot average so not quite at your levels yet.

Nothing to do with me and not sure if i'm correct but if you had say 5 GT31's and done 1 run of 40 knots and the rest were say 35 knots. Would this not give you a 40 knot average if you combined the tracks?

Just something i was thinking about.

cheers.....

Haha! Averages dont work that way unfortuately! But cunning idea c'apn

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AUS1111 said...

As far as carrying two or more 31's, I think it's fair enough to pick the quickest one provided you then use that track for all of the categories.

It wouldn't be reasonable, for example, to take the 2 sec of one unit and the alpha from another.

+1 That's what I was trying to say Chris, you make more sense, who knows which one you would have grabbed in the shop. Redsurfbus I wouldn't average the two for the same reason.

Not thinking about doing by the way!

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lao shi said...

Do people want me to add whether the file comes from a GT11 or 31 for the ranking?

I don't think so but Doppler only should be used, i doubt there will be any trackpoints in about the top 20 or more anyway
And include the date

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AUS1111 said...

As far as carrying two or more 31's, I think it's fair enough to pick the quickest one provided you then use that track for all of the categories.

Thanks Chris that is what I have been doing all the time anyway, my query came because I really wanted to use the higher number which I had not claimed in the past and at the end of the day it is a legit number so fine to use