Forums > Windsurfing   Gps and Speed talk

LOCOSYS wil not replace GW-60 broken band

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Created by bedzplane > 9 months ago, 23 Feb 2018
Carindale
QLD, 292 posts
20 Nov 2018 7:33PM
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decrepit said..
Probably a different alpha then, That's why it's good to process your own data, (especially with alphas,) you can see what's going on.
The 20 on the watch may have just been within the 50m using doppler but just outside using trackpoints. That would let you know that you're going too wide. if it's a valid alpha using both methods, there should only be fractions of a knt difference.


www.ka72.com/Track/t/360529

Here is the track from 3/11/18. The watch said just over 20 knot alpha and after uploaded to KA it was knocked back...sorry it was reduced to 19.634. Not sure if it was the same alpha but I'm pretty sure it was the same turn.

decrepit
WA, 8971 posts
20 Nov 2018 5:56PM
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Carindale said..

www.ka72.com/Track/t/360529

Here is the track from 3/11/18. The watch said just over 20 knot alpha and after uploaded to KA it was knocked back...sorry it was reduced to 19.634. Not sure if it was the same alpha but I'm pretty sure it was the same turn.


all I get is cesium, how do I download the file?

Cocky2
QLD, 114 posts
20 Nov 2018 8:26PM
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decrepit said..

Carindale said..

www.ka72.com/Track/t/360529

Here is the track from 3/11/18. The watch said just over 20 knot alpha and after uploaded to KA it was knocked back...sorry it was reduced to 19.634. Not sure if it was the same alpha but I'm pretty sure it was the same turn.



all I get is cesium, how do I download the file?


You download tracks from the "search " menu.

sailquik
VIC, 4333 posts
20 Nov 2018 9:26PM
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decrepit said..

Carindale said..

www.ka72.com/Track/t/360529

Here is the track from 3/11/18. The watch said just over 20 knot alpha and after uploaded to KA it was knocked back...sorry it was reduced to 19.634. Not sure if it was the same alpha but I'm pretty sure it was the same turn.



all I get is cesium, how do I download the file?


Sent you the link Mike.

decrepit
WA, 8971 posts
20 Nov 2018 7:12PM
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OK,
Got it, and you're right it's the same gybe, but you went wide, so it's very short, only just got it into the watch's 300m.

so here's what it looks like with Real speed.



You can see the total distance is only 313.2m. because that's where trackpoints puts your 50m separation.
If you add another 3m and calculate for 53m
here's what you get.




So another 3m separation gives you an extra 43m total distance, lifting the average speed.
So I conclude from this that the watches doppler calculation of separation is an extra 3m here. So safest if you want to make sure of your alphas, aim for 47-48m not 50m

Carindale
QLD, 292 posts
20 Nov 2018 9:18PM
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decrepit said..
OK,
Got it, and you're right it's the same gybe, but you went wide, so it's very short, only just got it into the watch's 300m.

so here's what it looks like with Real speed.



You can see the total distance is only 313.2m. because that's where trackpoints puts your 50m separation.
If you add another 3m and calculate for 53m
here's what you get.




So another 3m separation gives you an extra 43m total distance, lifting the average speed.
So I conclude from this that the watches doppler calculation of separation is an extra 3m here. So safest if you want to make sure of your alphas, aim for 47-48m not 50m


Hey thanks for checking it out.

decrepit
WA, 8971 posts
20 Nov 2018 7:49PM
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Carindale said..

Hey thanks for checking it out.


It's really not a problem, having your own software can tell you a lot about what is happening, this case demonstrates that rather well.

Carindale
QLD, 292 posts
21 Nov 2018 7:03AM
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decrepit said..

Carindale said..

Hey thanks for checking it out.



It's really not a problem, having your own software can tell you a lot about what is happening, this case demonstrates that rather well.


Software analysis is very interesting. Again thankyou for your time and energy.

This case also demonstrates that the watch gave a higher alpha on the day than what KA gave and subsequently posted on gpstc.......hence my initial point that I made to Sue, that I noticed a difference on an alpha when she asked if any scores were 'knocked back' by KA.

decrepit
WA, 8971 posts
21 Nov 2018 9:34AM
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Yes, but it could just as easily been the other way round, if the doppler track had been 3m inside the trackpoints, you may have got a full 500m 21kt alpha from KA72. and still had a 20 on the watch



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"LOCOSYS wil not replace GW-60 broken band" started by bedzplane