Hi Swied, we are using Grmin Etrex and Gecko 201, looks like the 305 is a goodie, is it easy to download and analyse the data?
It is pretty easy. You just plug it into your computer, and click upload in the software (or on the website). The graphs are generated automatically. If you want to analyze the data yourself you can export it to a text file with XML formatting. I attached a sample file below. Open it with Notepad, Word or any other text editor. It gives you Lat., Long., elevation, and speed, at 1 minute intervals. I’m not sure if this will be sufficient for surfing since most waves last less than 1 minute. I haven’t played around with it too much though. Maybe there is some way to increase the sampling rate.
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By the way best to use TWO ziplock bags, one tends to let water in.
The unit was $350. That’s too much for ziplocks. I was thinking about buying a more rugged water proof sack.
It’s like this: I switch on the gps unit, clear the previous data, put it in a ziplock bag down the back of the wettie and go surfing, then read what the machine spits out. . … . the same as Terry, Bill, and the guys at Surfermag do… . . … you don’t think I can perform this task? . . . or are you saying that I am making up the data ?
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Well, that’s not quite the way I do it–I don’t put it “down the back of the wettie”. Instead I mount it near the top of my arm (on the side that will be closer to the shore when I’m riding a the wave). Otherwise a substantial fraction of the solid angle available for satellite reception can be blocked by one’s body. That can lead to a loss of triangulation accuracy or, even worse, not enough satellite signals reaching the GPS, resulting in erroneous readings if the GPS is (internally) programmed to estimate position and speed during momentary data stream interruptions (e.g. Gecko 201).
[An aside: Obviously (for the same reason) any measurements made if/when one gets partially or (especially) totally “covered” should be considered as highly suspect.]
When I have a little free time, I plan to mount my unit on the top of a Gath–where it will be even less susceptible to this sort of problem.
But if a 3 foot wave has a speed of ~16 KPH ( thats 1/2 speed of an Olympic 100 m runner), then thats 4.4 m/s or 22 m in 5 secs.
How fast is a closeout? I mean in reality the curl is moving incredibly fast in a closeout compared to actual speed of the wave(which may on reality almost be standing still when you look at the shoreward speed). A 4m/s moving curl does not sound at all fast, but 60 kph does sound optimistic I agree and certainly for 5 seconds in a straight line. But then again slater may have done a figure eight leaving him back in the curl. Isn’t high performance surfing about drawing the longest possible lines on a wave?
All you have verified is that when you measure the speed of your surfboards, they come out TWO TIMES as fast as the speeds others get on similar size waves.
Coincidentally that is what observers on the beach often report
Isn’t high performance surfing about drawing the longest possible lines on a wave?
If yoiu’re talking WCT style performance, yes… mixed with skater tricks. But… different strokes. Some waves - like Pipeline - aren’t about the longest lines. They’re about positioning and grace under pressure.
My thing is tuning in to the wave. I’m past the point of trying to prove anything with my surfing, since I’ve been doing it over 42 years (although I still think I rip). When I surf, I’m dancing with the wave. I’m aware of where the wave’s energy is, and I let that dictate my ride.
Most surfers seem to have no idea what the wave is doing. They’re more concerned with what they’re doing, and they do it without fully considering their dance partner. Going right when they should have gone left, turning too late, turning too early, straightening out when they should have gone for it, jumping off their board when they should have done a gracefull kickout…
Heavier spots cetainly have much better surfers. Even though I’ve surfed Kauai for over thirty years, I’m always amazed at the level of surfing here. 12 year old kids doing super-late, super-deep drops on triple overhead slabs that crash into rocks right after the takeoff. Guys so deep in the tube it doesn’t seem possible to make it out… but they do. Surfing grandmas and grandpas. I’ve surfed with families that had three generations in the water at the same time.
You have not shown that you go twice as fast as the next faster surfer via your videos. In fact, it looks pretty similar to what any log can achieve.
Moving the goalposts again I see.
A couple of years ago when I did video analysis I was told by yourself (and others) that video analysis was impossibly inaccurate and I should shut up until I had GPS based speeds recorded.
Now, you are trying to sell me the idea that by merely eyeballing a video clip you can negate GPS readings
Not very consistent thinking (not up to your usual high standard), this leads me to suspect that you have pre decided the answer.
Thanks for your input though Blakestah, it is always appreciated . . . .
You have not shown that you go twice as fast as the next faster surfer via your videos. In fact, it looks pretty similar to what any log can achieve.
Moving the goalposts again I see.
A couple of years ago when I did video analysis I was told by yourself (and others) that video analysis was impossibly inaccurate and I should shut up until I had GPS based speeds recorded.
Now, you are trying to sell me the idea that by merely eyeballing a video clip you can negate GPS readings
Not very consistent thinking (not up to your usual high standard), this leads me to suspect that you have pre decided the answer.
Thanks for your input though Blakestah, it is always appreciated . . . .
What’s average wave-beachward V at your break Roy?
Have you gone completely straight in to get y baselines on the day? Is it like 15mph? You could derive it from your tracks, though, couldn’t you.
Then your trim x axis distance would give the total vector diagonal which would get you up to your speed…
It’s all a diagonal line with the wave’s beachward V as a (y vector) baseline speed and I thought an average wave was moving 15 or so, which would mean your x trim would have to be 15 to get you to 30mph speed
Math people, is it a mathematical/physical truism that you couldn’t get an isolated x (trim) component higher than the isolated y (straight beachward) on a rolling wave?
Math people, is it a mathematical/physical truism that you couldn’t get an isolated x (trim) component higher than the isolated y (straight beachward) on a rolling wave?
No it isn’t a truism, we are getting 37mph on a wave with a beachward speed of 10 to 15 mph, which gives us an x component of 35.6 to 33.8 mph, although we really have to take into account the vertical movement as well.
That’s a nice little unit there, much the same as what I am using ( we can also graft into google earth with the garmin tracks) the main advantage of the one you posted is its waterproof housing and the fact that it can store more data. .
been keeping an eye on this thread, all very interesting if somewhat over my head.Noticed this clip from the waterproof speedometer thread by ojshjs of bodyboarders measuring their speeds with what looks like gps.Interesting to note that the fastest claimed speed recorded of the day was 31 mph (i think).I’ll state for the record that i am a kiwi so probably am somewhat biased in favour of Roy not being full of you know what…but i guess its always possible that he has hosted the clip under an alias as an elaborate hoax to make his recorded speeds seem more credible.
Goddamit, why wont someone just try one of Roys Boards and tell us impartially how fast it seems to be going, relatively speaking (or relativity speaking). Silly, you planning any long weekend trips soon ??? I seem to be listening for the same arguments for 3 years.
Do you have any video of where you are really flying? I’d like to see what it looks like. I downloaded a couple from your web site but they must have been the wrong ones. Max velosity and you got to be kidding. Takes me a long time to down load, so if you could tell me where to find your really fast surfing videos, I’d love to see them.
We have already ( long ago) established that the maximum speed on a wave is related to the the maximum speed of the wave.
I question this so called established fact. Doesn’t infact deep water swell move faster than breaking waves, yet noone surfs faster (if at all) on these than on breaking waves? Doesn’t gravity play an important role which should indicate that the slope of the wave matters more than it’s actual speed(Equipment on snow seems to be going incredibly fast compared to any surfboard without having an avalanche chasing them)? Isn’t it the energy of the wave that generates the propulsion for a surfboard? Although the energy of a wave is very much related to the speed of a wave, I really doubt the maximum speed of a surfboard is closely related even to the energy of that particular wave. If you double the period of a swell(height remains constant), then speed and the energy of that wave increases by an incredible amount. Does the speed of the board increase by the same amount?
Secondly, for high performance surfing, wouldn’t it be more interesting to messure acceleration(direction changes) than flat out (sustained) top speeds?
Given a 6 foot wave and without all that many tops and drops, I’d think that angle would be incidental–your track and net speed in the given timeframe over earth surface would be what it is.
Assuming that the surfer travels 16 metres in one second, and drops 2 metres during that second, then the horizontal component of the vector will be about 15.87 mteres per second, about a one per cent difference, so it isn’t a big deal in that particular case.
the greater the size of a craft the LOWER its maximum top speed
Totally untrue, in fact all else being equal, the opposite is the case
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and the only way to increase the top speed is to increase the width
Incorrect , there is more than one way to increase the top speed of a board, and adding width is not necessarily one of them because when driving down the line only one rail is in action at a time
Having said that, I have been riding 27 inch wide bords for a long time. . . . but the widest part of the board is not in use when going fast
the greater the size of a craft the LOWER its maximum top speed
Totally untrue, in fact all else being equal, the opposite is the case
Roy,So a tug boat has the abilty to go faster than a jet boat ? And a supertanker has a higher top speed than every other craft because its bigger? And tow-in boards at 5 foot long and 12 inches wide are the slowest of all? That would be perfectly in line with your personal speed recordings and logic that defies reality.
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and the only way to increase the top speed is to increase the width
Incorrect , there is more than one way to increase the top speed of a board, and adding width is not necessarily one of them because when driving down the line only one rail is in action at a time
Having said that, I have been riding 27 inch wide bords for a long time. . . . but the widest part of the board is not in use when going fast
Roy, your theories are historically unparented and mathematically disproven and you refuse to supply any sensible proof or independant corroboration apart from your own constantly repeated GPS figures. Your videos clearly disprove your own claims ( and thats not just my opinion or else you would have sold many boards) and yet you remain steadfast to your private fantasy or is it a serial prank, maybe the jokes on us for listening to you for so long, you sly dog , eh??
