Forums > Windsurfing General

How Fast in Chop?

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Created by Gorgo > 9 months ago, 30 Nov 2016
Magic Ride
719 posts
2 Dec 2016 8:05AM
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Never windsurfed Manhattan Beach, but used to go down their to party though. I been to Long Beach several times, when I was learning how to windsurf. Some good spots their. I lived in Camarillo at the time, so Ventura and Leo Carrillo were the closest. Good times their, but doesn't compare to Oregon. Oregon is much windier than California for some reason. I get so many more sessions up here than in California. Never knew it until I moved here. But I do miss those beautiful cali girls glistening on the beach in those string bikinis.

Ian K
NSW, 2859 posts
2 Dec 2016 10:44AM
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Magic Ride said..
But I do miss those beautiful cali girls glistening on the beach in those string bikinis.

You shouldn't have said that.


Magic Ride
719 posts
2 Dec 2016 9:05AM
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That's classic IanK, thank you...

JonesySail
QLD, 930 posts
2 Dec 2016 2:01PM
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This sort of chop? Ocean sailing is 90% of what I sail, flat water for me is boring after a few runs it's also a much longer drive away so sailing closer to home maximises TOW.

How fast? 25-30in this is absolutely flying and heaps of fun and a serious workout, I've done a 22+ 1 hour out there so that's quick, or as the guys drinking beers from the top roof top of nearby resort calculated , 1.5 min from island to shore!
And if you want to open up a can of worms this is where the whole entire GPS 'comparison of speed only' really doesn't make sense. Every spot has its own challenges and as such max speeds will vary massively , 25-30 in the ocean is flying, where as 25-30 on a speed run isn't fast at all. So what is 'fast sailing in chop' will depend on the local conditions. 40knts ocean is doable in patches, again depends on location, sometimes you can get massive long flat water patches between waves.
Local spot records on KA72 is a pretty cool idea.
Is there more people looking at pushing harder in open water these days? boards specifically developed for it... the 'fox' 'blast' 'KA GPS' etc
Waste harness, forgiving board , stiff fin, and fat softer foot pads are key ingredients, I love the open water blast, max adrenaline, max workout.
I'd love to see more open water races, maybe even the old school surf slalom, in out through the waves.
Speaking of 20+Seabreeze is calling!






Sparky
WA, 918 posts
2 Dec 2016 1:02PM
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Chop can vary so much. Short frequency chop can be a lot worse than large ocean swells. Sometimes in large swell you can bare down with the wave face and pick large gaps of flat water. In cross shore wind, swell will refract to be head on near the beach and more cross shore further out.

Ian K
NSW, 2859 posts
2 Dec 2016 4:18PM
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J








That's it Sparky, the photo needs to show lumps on the horizon for it to be properly nice and lumpy.

The Sandon Point speed run. (another Nick Nelson photo)

Magic Ride
719 posts
2 Dec 2016 2:48PM
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Chop or no chop, how do ya want your chops? I'll take mine well done. Wanna beer? Yes! I think we all need a beer after reading about all this chop shop. Lets hop out of the chop and move onto something else. LOL...

Mastbender
1896 posts
2 Dec 2016 3:18PM
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Magic Ride said..
Mastbender,

Is this Leo Carrillo you're talking about? I used to windsurf their before I moved to Oregon.


No, about 200 miles north of there, just south of the entrance to Big Sur by Hearst Castle, a place called Arroyo Laguna.

decrepit
WA, 9212 posts
2 Dec 2016 7:01PM
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Magic Ride said..
Decrepit,

If you recall, I also wrote that my Speedometer and garman GPS also matched up with Mytracks as well. That's two different sources. Do I need to buy an Acura to prove my point to you?



All that does is prove your car speedo is relatively accurate, it doesn't say anything about your GPS.

Here's why we need good accuracy, the GTC top 20, 2sec table.




As you see some of these positions are only separated by 0.02 knots, So we need an accuracy of around 0.01% to do this reliably, a car speedo at 5% is so far away from this it makes sailquick laugh.

brynoz
QLD, 172 posts
2 Dec 2016 9:23PM
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Shifu said...
Here's the Redcliffe Speed Strip. If your spot is not like this it's not really choppy:












Good point. In real chop how could anyone be on anything but bump and jump gear which would have an upper limit of ~35 best case.

PhilSWR
NSW, 1104 posts
2 Dec 2016 10:01PM
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Some great pics there, love the open ocean stuff.

For me, who really cares how fast you go in river chop, millpond flat water or proper open ocean? Who ever comes in with the biggest smile at days end is the clearly winner

Magic Ride
719 posts
3 Dec 2016 3:08AM
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Decrepit,

I see what you're saying. Point made. The closest mytracks is for example is 29.1, 37.3 and 38 MPH etc. See mytracks is accurate for its data received, but doesn't draw out the decimal as far, but you're looking for a more fine tuned number such as 37.27 mph. You wanted the decimal brought out farther. I was trying earlier to understand what is he talking about. Now we're on the same page. All is good mate.

decrepit
WA, 9212 posts
3 Dec 2016 1:27PM
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Magic, your still not there, the point is, how inaccurate car speedos are.
It's not just a case of the extra decimal point, it's that you can't judge the accuracy of a gps by comparing it to a car speedo.
Because the car speedo can be out by 8% and we need much better than that, and typically if a gps has a good sky view it will be far better than a car speedo.

Ian K
NSW, 2859 posts
3 Dec 2016 4:21PM
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Yes but didn't we all check our gps against a car speedo before we got confident in the glitch filtering of the approved downloading software? I discovered an intermittent glitch in a Garmin gps by checking against a car speedo. Car speedos may not have the absolute accuracy of a gps but they are pretty glitch proof. Do we know how thorough the glitch filtering is on the mytracks software?

Would the minimum speed recorded by a car speedo doing alphas on a quiet roundabout be more or less accurate than the minimum speed recorded by the GPS on the dashboard? I'm not too sure.

hardie
WA, 4003 posts
3 Dec 2016 2:35PM
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decrepit said..
Magic, your still not there, the point is, how inaccurate car speedos are.
It's not just a case of the extra decimal point, it's that you can't judge the accuracy of a gps by comparing it to a car speedo.
Because the car speedo can be out by 8% and we need much better than that, and typically if a gps has a good sky view it will be far better than a car speedo.





Mike what if you're really accurate at counting in your head like 1001 1002 1003..... 1022 and a bit, You could do a count for each run and say run1 was to a count of 22 seconds, and just a little bit more, etc then you calculate the distance you travelled with prior references to google earth, and use the distance by time method to calculate each run? For those with poor memories you could bring along a waterproof marker and waterproof paper, and write down each run, wouldn't that be at least the cheapest way to be involved in speedsailing? then all the money you saved in buying multiple gps's and batteries and electricity for charging, could be spent on fast fins, that would make you go even faster, meaning you would ending up counting less seconds per run 1001, 1002, 1003, ..... 1021 and no bits.?? You could even get really scientific with the count like saying in your head "thousand and one, thousand and two, thousand and three, thou". Stop Counting. Given there;s 14 letters in each count if you stop at "thou" thats 4/14's of a second, so it can be as accurate as you want it?

WazzaYotty
QLD, 301 posts
3 Dec 2016 5:15PM
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decrepit said..
Magic, your still not there, the point is, how inaccurate car speedos are.
It's not just a case of the extra decimal point, it's that you can't judge the accuracy of a gps by comparing it to a car speedo.
Because the car speedo can be out by 8% and we need much better than that, and typically if a gps has a good sky view it will be far better than a car speedo.


My Subaru Forester, with the correct tyre size at the correct inflation, reads 108km/hr and at the same time both my GT31 and my iPhone Co-Pilot app read 100km/hr.

Sparky
WA, 918 posts
3 Dec 2016 3:37PM
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hardie said..

decrepit said..
Magic, your still not there, the point is, how inaccurate car speedos are.
It's not just a case of the extra decimal point, it's that you can't judge the accuracy of a gps by comparing it to a car speedo.
Because the car speedo can be out by 8% and we need much better than that, and typically if a gps has a good sky view it will be far better than a car speedo.






Mike what if you're really accurate at counting in your head like 1001 1002 1003..... 1022 and a bit, You could do a count for each run and say run1 was to a count of 22 seconds, and just a little bit more, etc then you calculate the distance you travelled with prior references to google earth, and use the distance by time method to calculate each run? For those with poor memories you could bring along a waterproof marker and waterproof paper, and write down each run, wouldn't that be at least the cheapest way to be involved in speedsailing? then all the money you saved in buying multiple gps's and batteries and electricity for charging, could be spent on fast fins, that would make you go even faster, meaning you would ending up counting less seconds per run 1001, 1002, 1003, ..... 1021 and no bits.?? You could even get really scientific with the count like saying in your head "thousand and one, thousand and two, thousand and three, thou". Stop Counting. Given there;s 14 letters in each count if you stop at "thou" thats 4/14's of a second, so it can be as accurate as you want it?


All well and good, BUT. The original system was surely the best for calculating knots speed. Weren't knots tied in rope and let out the back of the boat?. The faster the "knots" were released, the faster you were going. I'm going to try this, does anyone know how far apart the knots need to be tied on the rope?

hardie
WA, 4003 posts
3 Dec 2016 3:48PM
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Sparky said..




All well and good, BUT. The original system was surely the best for calculating knots speed. Weren't knots tied in rope and let out the back of the boat?. The faster the "knots" were released, the faster you were going. I'm going to try this, does anyone know how far apart the knots need to be tied on the rope?


I suppose the issue with our solutions would be lie detecting? So in order to avoid in inverted commas CHEATING, to be really scientific, you would have to submit a picture of your nose with a ruler over it before each run, then after you post your results, another photograph of your nose length, and if it grew in length from the first photo, that would make it an invalid result, and therefore ineligible? I think we got it covered!!

Paddles B'mere
QLD, 2377 posts
3 Dec 2016 5:48PM
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You can work it out for yourself. A knot is 1 nautical mile per hour. The knots were simply the number of knots through the hands within a given time so therefore the gap between the knots is variable depending upon the amount of time you wish to use to perform the measurement.

Sparky
WA, 918 posts
3 Dec 2016 3:54PM
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Quote;

The chip log was "cast" over the stern of the moving vessel and the line allowed to pay out.[5] Knots placed at a distance of 8 fathoms - 47 feet 3 inches (14.4018 m) from each other, passed through a sailor's fingers, while another sailor used a 30-second sand-glass (28-second sand-glass is the currently accepted timing) to time the operation.

Sparky
WA, 918 posts
3 Dec 2016 3:54PM
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I supposed you'd have to be sailing a tandem?

Sparky
WA, 918 posts
3 Dec 2016 3:58PM
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Does anyone know where to buy a 30 second sandglass? Would I need a waterproof pac for it? Would it perform differently in chop?

decrepit
WA, 9212 posts
3 Dec 2016 5:35PM
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WazzaYotty said..


My Subaru Forester, with the correct tyre size at the correct inflation, reads 108km/hr and at the same time both my GT31 and my iPhone Co-Pilot app read 100km/hr.


There you go, 8% high exactly

decrepit
WA, 9212 posts
3 Dec 2016 5:47PM
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Sparky said..
Does anyone know where to buy a 30 second sandglass? Would I need a waterproof pac for it? Would it perform differently in chop?


Do you get a coriolis effect with sand running through a hole???
Do you need a left handed or right handed sandglass for the different hemispheres?

Don't think you need a water proof pac, as they are designed to be turned around to work both ways, so they must be sealed.

Chop is a hard one, as the sand will flow quicker when you land and go up, but flow slower as you hit the top and drop. Possibly depends how many Gs you develop in both directions. If you actually get air and float down Gs would be considerably reduced, if you go into a power dive, you could go negative and the sand would start flowing back wards, so if you really cushioned the landings, 30s could be stretched to almost a minute.
On the other hand, if you cushion out the top of the ramp, but land really hard, the 30s could be shrunk to 15s.

If you can borrow the tardis I'm sure you'd have no trouble buying one from any 16th century general store.


Paddles B'mere
QLD, 2377 posts
3 Dec 2016 8:00PM
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You ask too many questions decrepit, it's a saturday night dammit

Ian K
NSW, 2859 posts
3 Dec 2016 8:14PM
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Well if the flow of sand is linear with gravity the ups and downs, no matter how jolted should cancel out as long as the glass ends up at the initial height. (Maybe not ?) Water is horizontal so that condition is met. This got me googling. There doesn't seem to be an answer! How does a 30 second hour glass perform on the moon?


www.technologyreview.com/s/418993/the-mystery-of-sand-flow-through-an-hourglass

edit. Found it

arxiv.org/pdf/0707.4550.pdf

Flow rate W varies with the sqrt of gravity.


W = Cρb√g(D0 − kdp)5/2

But then again maybe we didn't want it linear for accuracy in chop?

This will keep me awake.

decrepit
WA, 9212 posts
3 Dec 2016 6:29PM
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Ian K said..
Well if the flow of sand is linear with gravity the ups and downs, no matter how jolted should cancel out as long as the glass ends up at the initial height. Water is horizontal so that condition is met. This got me googling. There doesn't seem to be an answer! How does a 30 second hour glass perform on the moon?


www.technologyreview.com/s/418993/the-mystery-of-sand-flow-through-an-hourglass/


But as I was trying to explain, the induced Gs aren't necessarily symmetric. Depends how you absorb the chop, it would be easy to favour either the lift at the top or the crunch at the bottom.
I have a feeling that on the moon the sand would flow slower, but then the moon having less gravity, time itself would be different!

decrepit
WA, 9212 posts
3 Dec 2016 6:30PM
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Paddles B'mere said..
You ask too many questions decrepit, it's a saturday night dammit


What, 2 little questions are too many? Have another beer, you'll feel better.

Ian K
NSW, 2859 posts
3 Dec 2016 9:32PM
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Did some sums. You were right Decrepit. Chop does affect time in an hour glass because sand flow is non-linear. My initial guess, (Shouldn't have retracted it ), was also right but for the wrong reasons. If sand flowed linearly with gravity, ( which it doesn't) then it would all cancel out if the vertical velocity ended up as zero again. i.e., the integral of the accelerations was zero. As long as you don't go too high so that g changes that is.

What else is there to do on a Saturday night?




Magic Ride
719 posts
3 Dec 2016 9:28PM
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I hear decrepit is buyin. Beers for all. How much more chop talk do we got? I think a new bumper sticker should be in the making. "GOT CHOP"?



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"How Fast in Chop?" started by Gorgo