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How high can you jump?
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isobars



Joined: 12 Dec 1999
Posts: 14310

PostPosted: Tue Nov 20, 2012 5:31 pm    Post subject: Reply with quote

I've sailed there, seen the rocks, heard them cursed. The CA sailors who claim the rocks don't exist are a whole threadful of angry left coast wave sailors who ran out of "You're a racist" insults.
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keycocker



Joined: 10 Jul 2005
Posts: 3441

PostPosted: Tue Nov 20, 2012 6:24 pm    Post subject: Reply with quote

Jumps, speed, and other worlds records are a regulated thing.
They have been going over fifty knots with a speed gun in the Gorge from years ago, but the world record just passed fifty recently.
Same with jumps, that event in Hookipa doesn't count.
The GPS records are a lot higher than any official speed.
The reason that require a nearly unaffordable jury with sealed instruments should be obvious. When I handed out GPS at the Navman Speed event, one kid noticed that the longer they lay on tne desk,the faster they said the event tent was flying across the beach.
the one he grabbed said 6knots. Mark said just reset them to zero as they take them out, but the kid wanted that unit anyway.
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boardsurfr



Joined: 23 Aug 2001
Posts: 566

PostPosted: Wed Nov 21, 2012 6:37 pm    Post subject: Reply with quote

keycocker wrote:
The GPS records are a lot higher than any official speed.

That may well be true for old (non-doppler) GPS gear, but the gear currently recommended on the GPS speedsurfing sites (Locosys GT-31 in doppler mode) is quite accurate. For example, Antoine Albeau's record from today over 500 m was 52.05 knots measured with the official equipment, and 51.96 knots measured with GPS (see http://www.gps-speedsurfing.com/default.aspx?mnu=user&val=111117&uid=412). His 5x10 second average, which is usually used for GPS speed, was 52.13 knots, also very close. The same is true for the other sailors in Lüderitz that post on gps-speedsurfing.com.

He did not submit this as an "official" GPS record; if he had, the GPS numbers would have gone down a bit (due to subtracting error margins, I think). But either way, the GPS results are almost always within 0.1-1 knot of the official (gate) measurements.

However, if you put on a Garmin Foretrex or something similar, and sail a few days, chances are that the Garmin will tell you that you hit 40 knots, when you actual top speed was less than 30. I've seen it happen several times to different sailors.
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dtroup



Joined: 16 Jul 2000
Posts: 38

PostPosted: Fri Nov 23, 2012 3:48 pm    Post subject: GPS speeds Reply with quote

The problem with consumer GPS is that it only gives you a location once per second, and in high dynamic sports like Windsurfing, a lot can happen in one second. In addition to the slow data rate, the precision is roughly 5 meters, so given those two variables, its no surprise that speed readings from GPS systems can vary wildly. Especially when compared to a speed timing/trap system.

The Locosys has a similar GPS as to what we have in the XensrCase, but in addition to the GPS data, we also mix in motion data to give data at 400 times per second, giving amazing precision to the data.

The whole goal here is to offer not only amazing precision in speed, but also give you 3D location data for things like jumps, tricks, etc.
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almineev



Joined: 25 Apr 2010
Posts: 22

PostPosted: Sat Nov 24, 2012 3:59 am    Post subject: Reply with quote

boardsurfr wrote:
However, if you put on a Garmin Foretrex or something similar, and sail a few days, chances are that the Garmin will tell you that you hit 40 knots, when you actual top speed was less than 30. I've seen it happen several times to different sailors.

Carry two Garmins? and average them out in software post processing.
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nw30



Joined: 21 Dec 2008
Posts: 1791
Location: The eye of the universe, Cen. Cal. coast

PostPosted: Tue Nov 27, 2012 12:25 am    Post subject: Reply with quote

How high do you need to go?



Just wondering.
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techno900



Joined: 28 Mar 2001
Posts: 1492

PostPosted: Tue Nov 27, 2012 9:42 am    Post subject: Reply with quote

Quote:
boardsurfr wrote:
However, if you put on a Garmin Foretrex or something similar, and sail a few days, chances are that the Garmin will tell you that you hit 40 knots, when you actual top speed was less than 30. I've seen it happen several times to different sailors.


I have carried a Garmin Foretrex 201 for the last 8 years on EVERY windsurfing outing, which is over 600 days of windsurfing. Only once has it given a bogus speed (105 mph). The rest of the time it has been exceptionally consistent. I also record all the data after each outing.

I wear it on an arm band inside a Aquapac (which as had a few leaks repaired).
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girsang



Joined: 16 Jun 2000
Posts: 51
Location: San Francisco

PostPosted: Tue Jan 08, 2013 1:09 pm    Post subject: Back to the original topic Reply with quote

Here's a competing product.

http://ces.cnet.com/8301-34441_1-57562607/how-high-can-you-jump-measure-with-vert/
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keycocker



Joined: 10 Jul 2005
Posts: 3441

PostPosted: Wed Jan 09, 2013 12:11 am    Post subject: Reply with quote

I have never had a chance to speak to someone with your considerable experience in using a Garmin. Does it show speed at times while sitting still on the table like the Navman we used in the Navman Speed Series?
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cbknap



Joined: 03 Jun 1997
Posts: 300

PostPosted: Wed Jan 09, 2013 7:16 pm    Post subject: Reply with quote

the video posted by gerrit is just awesome.


http://www.windsport.com/features_article?news_id=765
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