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Offline RonJ

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Re: Vendée Globe
« Reply #20 on: December 15, 2020, 08:18:06 PM »
I am also a FAA licensed commercial pilot (retired) as well as a CG licensed Merchant Marine Officer (retired).  The 'computer' you were talking about mostly pertains to calculating the effects of winds on your aircraft's speed relative to the ground (among other things).  Your aircraft's air speed indicator only give you a relative speed indication (to the air).  It's use for navigational purposes is limited.  Mostly the air speed indicator is used to know how close you are to stalling, for setting your aircraft up during a climb, and for not exceeding your red line speed during a decent.  A boat, or ship, has a thru the water speed indicator as well.  It can only tell you how fast you are going relative to the water.  The water will also have a speed relative to the ocean bottom.  There are significant currents along the coast of Japan and of course the Gulf Stream along the coast of Florida.  So the thru the water speeds will only give you a 'ball park' number in relation to how fast you are going over the ocean bottom.  The important thing in this case (an ocean race) is how fast you are going over the ocean bottom and what is the distance.  The distance will be accurately determined by your WGS-84 charts (or maybe some British Admiralty ones).  Your speed can only be accurately be determined by using GPS (the best), or taking a couple of fixes relative to observable landmarks, or celestial navigation.  Celestial navigation is essentially similar to using landmass fixes because what you are doing is determining your position relative to a star, or planets zenith position on the surface of the earth.  You get these zenith positions from a nautical almanac but this is based upon knowing the exact time to the second of when your observations were taken. 

Yes, both GPS and celestial navigation depend upon the earth being spherical.  Both techniques will not work on a flat earth.
« Last Edit: December 15, 2020, 08:34:02 PM by RonJ »
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Offline Tom Bishop

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Re: Vendée Globe
« Reply #21 on: December 15, 2020, 08:36:38 PM »
The formula for speed is Speed = Distance / Time

If the distance is in question, then the speed is also in question.

The situation is fluids traveling within fluids. The winds and water are in motion. On board airplane airspeed indicators are similarly unreliable, and are not used for navigation. The local area of the airplane might be in motion faster than a larger area around that airplane, which might itself be in motion.


This is a joke, right?

Nope. The on-board instruments which give the true airspeed only detects the local wind or air flow around the wings, and is not used in navigation. That information is primarily used for banking maneuvers and such.

http://wiki.flightgear.org/Aircraft_speed

From that link: "Knowing TAS (True Airspeed) during flight is surprisingly useless - for navigation, ground speed is needed"

SteelyBob

Re: Vendée Globe
« Reply #22 on: December 16, 2020, 10:34:00 AM »
To be honest, you are both (@Tom Bishop and @DuncanDoenitz) engaged in something of a sidebar debate. For what it's worth, ASIs in aircraft aren't 'unreliable', they are both reliable and extremely important. They are also extremely useful for navigation, but they have limitations. As Tom rightly points out, they don't measure groundspeed, or 'gs'. Traditional navigation would involve correcting for the forecast wind, using either mental reckoning or the more sophisticated Dalton computer, and then updating position using either visual features or a ground based beacon such as VOR/DME. GPS has clearly made that process a lot easier, but then presumably FET proponents would take issue with the concept of a constellation of geo-stationary satellites.

For ships at sea a similar station exists. Sailors can measure their speed through the water, but cannot account for the movement of the water without measuring by some external means, such as celestial sightings (deeply problematic from a FET perspective) or again, GPS.

But leaving all of this aside, there is a much more fundamental truth that we need to establish here. Could a FET proponent, maybe @Tom Bishop, for example, please tell us how far the race route would actually be on a FET map, and therefore how fast, in terms of groundspeed, the boats would have to travel in order to make the kind of times we are discussing. We can then see whether or not the speed of water movement required would be credible.

I would also like @Tom to explain how the boats know where they are - how does GPS work, for example? Does celestial navigation work?

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Offline WTF_Seriously

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Re: Vendée Globe
« Reply #23 on: December 24, 2020, 12:27:59 AM »
It is tremendously and abnormally windy in that area. An assessment would need to take that into account.

Have been watching the last 5 days or so since the leader crossed under Tasmania.  Winds in the teens and boat speeds in the mid to low teens with some single digit speeds the majority of the time.  Certainly no "roaring 40s" or "furious 50s".  Will be interesting to see how many days it takes to reach Cape Horn.
« Last Edit: December 24, 2020, 01:07:34 AM by WTF_Seriously »
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Offline Tom Bishop

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Re: Vendée Globe
« Reply #24 on: December 24, 2020, 02:45:20 AM »
The speed is in question if the distance is in question.

The formula for speed is Speed = Distance / Time

If the distance is in question, then the speed is also in question.

The situation is fluids traveling within fluids. The winds and water are in motion. On board airplane airspeed indicators are similarly unreliable, and are not used for navigation. The local area of the airplane might be in motion faster than a larger area around that airplane, which might itself be in motion.

Quote
I would also like @Tom to explain how the boats know where they are - how does GPS work, for example? Does celestial navigation work?

GPS works via triangulation, like LORAN. The transmitters don't need to be in space for it to work.

Celestial navigation mostly involves looking at pointers to find which way is North or South, and determining the direction of East and West in relation.

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Offline RonJ

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Re: Vendée Globe
« Reply #25 on: December 24, 2020, 03:24:33 AM »
Celestial navigation mostly involves triangulation.  You use a nautical almanac to determine the zenith point of the star, planet or moon you are using for navigational purposes.  After using a sextant to measure the angle above the horizon you can use that data (and the exact time) to plot a line on your chart.  Repeat that process using other stars or planets.  Where the lines cross is your position via triangulation.  It's a difficult process because usually your vessel is in motion while you are taking the sights.  This motion has to be accounted for.  If everything is done correctly your position will be accurate to about 1 or 2 miles depending on how good of a navigator your are. GPS does the same thing but a microcomputer inside the receiver does all the calculations and all the observations are done very quickly so your vessels movement isn't much of a factor.  Both GPS & celestial navigation require that the earth be a sphere to properly work.   
You can lead flat earthers to the curve but you can't make them think!

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Offline WTF_Seriously

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Re: Vendée Globe
« Reply #26 on: December 24, 2020, 03:27:50 AM »
The speed is in question if the distance is in question.


Do you question your speed when you drive your car and don’t know how far you’ve traveled??  No, because you have a speedometer.

These vessels all have speedometers. Their speed is not in question. In the end their speed will confirm the distance as it’s been measured for navigation for decades if not centuries.

Sorry, Tom. It’s 2020 and distances on this planet, flat or round, are known and measured. You can’t bring out the 1850 argument that we don’t know them anymore. It totally discredits you.
Flat-Earthers seem to have a very low standard of evidence for what they want to believe but an impossibly high standard of evidence for what they don’t want to believe.

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Offline RonJ

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Re: Vendée Globe
« Reply #27 on: December 24, 2020, 03:44:43 AM »
Yes, vessels all have speedometers.  These all measure speed thru the water.  Unfortunately this speed thru the water isn't the most accurate.  If you were to take your boat up the Mississippi River your speed over the ground would be a whole lot slower than when you are going down the river even when your 'speedometer' was reading an identical speed.  There are some quite strong currents, even in the oceans so these have to be accounted for.  A sailboat going up the wind tacks back & forth so progress toward the final destination can be quite a bit different than what the boat's speedometer says.  What's important here is the course made good and the speed over the ground. 

Having said all that, it still is possible to take a vessel's position fix, send it to shore via Sat-C, and then chart all those positions and times to come up with an accurate position, speed, and distance traveled for all of the sail boats.  An accurate mileage figure can be determined as well as an average speed.  In the end you will be able to determine the distance between the longitude lines South of the Equator.   
« Last Edit: December 24, 2020, 05:05:10 AM by RonJ »
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Offline Tom Bishop

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Re: Vendée Globe
« Reply #28 on: December 24, 2020, 03:45:01 AM »
Roads are static. How would a boat know how fast the water it is in is moving?

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Offline WTF_Seriously

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Re: Vendée Globe
« Reply #29 on: December 24, 2020, 04:11:13 AM »
Roads are static. How would a boat know how fast the water it is in is moving?

The ACC is a known current. It doesn’t flow at 20 knots. I posted this earlier.

Once again, it’s 2020. Things like ocean currents have been studied and known for decades.
« Last Edit: December 24, 2020, 04:14:16 AM by WTF_Seriously »
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Offline stack

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Re: Vendée Globe
« Reply #30 on: December 24, 2020, 04:43:53 AM »
Roads are static. How would a boat know how fast the water it is in is moving?

The data is easily accessible:

"Information on the rate and direction of ocean currents via the Global RTOFS (Real-Time Ocean Forecast System) model is easily accessed through navigation software programs that download data in GRIB format."
https://www.yachtingworld.com/expert-sailing-techniques/pro-navigators-tips-on-how-to-use-the-oceans-currents-114981

So that's how they know how fast the water it is in is moving.

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Offline Tom Bishop

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Re: Vendée Globe
« Reply #31 on: December 24, 2020, 05:33:29 AM »
Quote from: RonJ
Unfortunately this speed thru the water isn't the most accurate.

Quote from: WTF_Seriously
The ACC is a known current.

The data is easily accessible:

"Information on the rate and direction of ocean currents via the Global RTOFS (Real-Time Ocean Forecast System) model is easily accessed through navigation software programs that download data in GRIB format."
https://www.yachtingworld.com/expert-sailing-techniques/pro-navigators-tips-on-how-to-use-the-oceans-currents-114981

So that's how they know how fast the water it is in is moving.

So the boat doesn't know and couldn't know with on-board instrumentation. Thanks for verifying that this argument that the boat can know its speed on its own is incorrect.

You have to assume that other data is correct, which It might not be, since the equation for speed requires a known distance.

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Offline WTF_Seriously

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Re: Vendée Globe
« Reply #32 on: December 24, 2020, 05:38:28 AM »
Quote from: WTF_Seriously
The ACC is a known current.

So the boat doesn't know and couldn't know with on-board instrumentation. Thanks for verifying that this argument that the boat can know it's speed on its own is incorrect.

https://en.m.wikipedia.org/wiki/Antarctic_Circumpolar_Current

https://oceancurrents.rsmas.miami.edu/southern/antarctic-cp.html

http://polardiscovery.whoi.edu/antarctica/circulation.html

The current is a known quantity. Just because you want to continue to repeat the lie that we don’t know what the speed of the water is doesn’t make it true. I’d give you some leeway if the math was relatively close but we are talking a a difference of a 3 knot current and a required 20 knot current to make the current account for the vast differences in time and distance witnessed. Your continued desire to make current or wind account for the extreme difference in what we measure doesn’t hold up
to any scrutiny.
Flat-Earthers seem to have a very low standard of evidence for what they want to believe but an impossibly high standard of evidence for what they don’t want to believe.

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Offline stack

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Re: Vendée Globe
« Reply #33 on: December 24, 2020, 05:40:47 AM »
Quote from: RonJ
Unfortunately this speed thru the water isn't the most accurate.

Quote from: WTF_Seriously
The ACC is a known current.

The data is easily accessible:

"Information on the rate and direction of ocean currents via the Global RTOFS (Real-Time Ocean Forecast System) model is easily accessed through navigation software programs that download data in GRIB format."
https://www.yachtingworld.com/expert-sailing-techniques/pro-navigators-tips-on-how-to-use-the-oceans-currents-114981

So that's how they know how fast the water it is in is moving.

So the boat doesn't know and couldn't know with on-board instrumentation. Thanks for verifying that this argument that the boat can know its speed on its own is incorrect.

You have to assume that other data is correct, which It might not be, since the equation for speed requires a known distance.

I think these guys and gals have all of the speed data they need regardless of what you would like to rail against. The bottom line is that this real world race doesn't fit an FE model and there's really no way around that fact. Unless, of course, this is part of the conspiracy.


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Offline Tom Bishop

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Re: Vendée Globe
« Reply #34 on: December 24, 2020, 05:41:43 AM »
Quote
The current is a known quantity

The equation for speed requires a known distance. Please provide proof that the methods used were accurate.

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Offline stack

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Re: Vendée Globe
« Reply #35 on: December 24, 2020, 06:02:37 AM »
Quote
The current is a known quantity

The equation for speed requires a known distance. Please provide proof that the methods used were accurate.

Ask these folks. They have all of the data for their tracking/modeling.



And I'm sure the captains know what's accurate or not because they are, well, racing one another for one. For two, their lives depend upon knowing where they are and when they will be somewhere else. Pretty rudimentary. If you have an objection to those folks knowing what they are doing, maybe contact the Vendée folks and express your concerns.

In the mean time, we'll be watching this insane race race around the globe.

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Offline Tom Bishop

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Re: Vendée Globe
« Reply #36 on: December 24, 2020, 06:06:59 AM »
Ask these folks.

So you don't actually know that you are correct and must make a number of assumptions. Okay.

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Offline WTF_Seriously

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Re: Vendée Globe
« Reply #37 on: December 24, 2020, 06:15:39 AM »
Quote
The current is a known quantity

The equation for speed requires a known distance. Please provide proof that the methods used were accurate.

Incorrect. You can measure ocean current with a stationary device. You need no information about distance whatsoever. It’s called math and science.  You should look into it sometime.

I make a living off of instrumentation and it being accurate.

It’s laughable the proof required to back measurements that FE can’t account for yet absolutely zero measurements or proof for concepts like UA and EA are required for them to be fact. Zero proof whatsoever.
« Last Edit: December 24, 2020, 06:35:08 AM by WTF_Seriously »
Flat-Earthers seem to have a very low standard of evidence for what they want to believe but an impossibly high standard of evidence for what they don’t want to believe.

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Offline stack

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Re: Vendée Globe
« Reply #38 on: December 24, 2020, 06:16:04 AM »
Ask these folks.

So you don't actually know that you are correct and must make a number of assumptions. Okay.

I know I'm correct because those folks know they are correct because the race and their lives depend on it. And the race is happening live, right now, and is trackable by us with all of the data they provide. You, on the other hand, just keep saying, "No," when it's right there in front of your face. Such a strange stance; evidence staring you in the face and you are still blind to it. To the extent that you fall back on the "you're making assumptions..." ploy. No, you're making assumptions that are based upon zero evidence. The evidence that I'm right is right there, watch the race and enjoy:

https://www.vendeeglobe.org/en/tracking-map

Again, unless you want to throw all of these folks into the conspiracy. That's your only way out. So you might as well pull that lever.

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Offline Tom Bishop

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Re: Vendée Globe
« Reply #39 on: December 24, 2020, 10:19:23 PM »
Quote from: WTF_Seriously
Incorrect. You can measure ocean current with a stationary device. You need no information about distance whatsoever. It’s called math and science.  You should look into it sometime.

Source? What device was used?

Quote from: stack
I know I'm correct because those folks know they are correct

In other words you are admitting that you don't know that you are correct. I see.