Great Circle routes

[Daydream believer]

Hard to believe that on a sailing forum there would be people who don't understand Great Circles, never mind believe that the Earth is flat.
I despair.

Well it is not entirely flat is it. Because there are mountains on the land & obviously waves on the sea.
We are not stupid.

 

[MADRIGAL]

Flat Earthers are too irrational for it to be worth trying. Eratosthenes' experiment provided ample evidence of the spherical nature of the earth; everything since then, up to and including eye witness accounts, simply confirms what he first demonstrated.

And of course, if you look at the horizon from a small boat at sea, you can see the curvature. Flat earthers must live in land-locked regions.

 

[capnsensible]

When you ask people on small boats how far away they think the horizon is, I've generally found that the answer averages around 20nm. It surprises them to discover that with a 2m height of eye above sea level, it's a tad under 3....

 

[zoidberg]

"During walkout to the 'plane, the navigator asked his young pilot 'Do you want to fly the Great Circle Route today or shall we just go straight there'..."

 

[Tremyporth]

I think I read in "The Lounge" that the Flat Earth Society has announced that its membership is expanding all around the globe.

 

[Alan S]

Well it is not entirely flat is it. Because there are mountains on the land & obviously waves on the sea.
We are not stupid.

I'm unsure as to whether you really believe it's flat(ish) or you just like to wind people up.
I think I'd prefer the latter.

 

[AntarcticPilot]

On YouTube there is a claim that there is a Great Circle route from England to New Zealand via the Drake Passage. Anyone know if it is true?

Quite likely, but you might bump into one of the South Shetland Islands - @JumbleDuck posted one on here, but it certainly came close to the SSI, and the scale was too large to be certain. Note that the stretching string trick won't work on that one - it will try and do the Great Circle the other way, as it's shorter. @JumbleDuck was posting to show the longest possible Great Circle sea passage.

 

[AntarcticPilot]

I have the impression Great Circle routes are a notion spilled from plane/merchant maritime world which is most often useless for a sailboat: it there any one ocean route where one might want to follow a GC route instead of a weather route? Where the increase in distance by not following a GC route is not more than offset by the advantage of better wind direction/speed? Even in very high latitudes, say Japan to Alaska, or the northern option in the Ostar, the GC route will always be subordinate to the existence of correct weather. In temperate latitudes, the big high pressure systems in the middle of the oceans will make half of the crossings deviate a lot from GC.
Carib to Azores for example, the difference between GC and loxodromy is a few tens of miles over 2000+, a weather route will usually be near that; whereas no one in his right mind would try and follow the GC going Canaries to Caribbean.
The Southern hemisphere has a lot less land so maybe sailboats GC routes make more sense there?
View attachment 171095

As you say, Great Circle Routes are of little interest to yachts; making good use of global wind patterns and ocean currents is more important. The Great Circle route to the Caribbean, for example, would give you a headwind and be against the North Atlantic Drift and Gulf Stream.

 

[AntarcticPilot]

Quite likely, but you might bump into one of the South Shetland Islands - @JumbleDuck posted one on here, but it certainly came close to the SSI, and the scale was too large to be certain. Note that the stretching string trick won't work on that one - it will try and do the Great Circle the other way, as it's shorter. @JumbleDuck was posting to show the longest possible Great Circle sea passage.

This is the England to NZ one, I think: Amazing map proving you can sail from Britain to New Zealand in a straight line ?

It certainly isn't feasible, and may intersect the Amundsen Coast of Antarctica! I'd also be worried about the Falkland Islands and Pete I Øy. I note that they are using a pretty low-resolution world map of dubious accuracy in the Antarctic, too. And, of course, a large part of it would mean sailing through solid pack ice!

 

[RunAgroundHard]

How do you define a straight line, plane or arc?

 

[Daydream believer]

I think I read in "The Lounge" that the Flat Earth Society has announced that its membership is expanding all around the globe.

It is a horizontal circle around the edge you wally- Honestly-- Some people
We all know the earth is round. But round like a saucer, it is not rectangular like a football pitch.
Did you do nothing at school-- other than pick your nose & flick the boggies at the blackboard?

 

[Daydream believer]

When you ask people on small boats how far away they think the horizon is, I've generally found that the answer averages around 20nm. It surprises them to discover that with a 2m height of eye above sea level, it's a tad under 3....

That is because of all the CO2 that Franksingleton is creating. It bends the line of sight so it makes the earth seem banana shaped.
Banana shaped earth

 

[wonkywinch]

Don't forget the special switch we have in the cockpit ..

 

[Biggles Wader]

Don't forget the special switch we have in the cockpit ..

View attachment 171125

And the really concerning thing about the chemtrail switch is that it is always "on" whichever way you push it.
There is no escape!

 

[Snowgoose-1]

Canceled. Pic not clear.

 

[wonkywinch]

And of course, if you look at the horizon from a small boat at sea, you can see the curvature. Flat earthers must live in land-locked regions.

I don't think you can. It's an illusion where you see a radius of only 3-4 miles so the impression is that it's curved.

I spent many hours staring out the front at 40,000 feet and you can't see curvature at that height. Concorde was different and I was fortunate enough to witness that a couple of times.

To put a plane's altitude in perspective, 40,000 feet is 7.5 miles. Here's a pic of a globe covering the route mentioned above. Picture how far 7.5 miles is on that globe. It's tiny, so a flight is really very close to the surface. The atmosphere is not much thicker so it's like a very thin membrane over the surface of the earth. A scary thought.

 

[Jonny A]

I have the impression Great Circle routes are a notion spilled from plane/merchant maritime world which is most often useless for a sailboat: it there any one ocean route where one might want to follow a GC route instead of a weather route? Where the increase in distance by not following a GC route is not more than offset by the advantage of better wind direction/speed? Even in very high latitudes, say Japan to Alaska, or the northern option in the Ostar, the GC route will always be subordinate to the existence of correct weather. In temperate latitudes, the big high pressure systems in the middle of the oceans will make half of the crossings deviate a lot from GC.
Carib to Azores for example, the difference between GC and loxodromy is a few tens of miles over 2000+, a weather route will usually be near that; whereas no one in his right mind would try and follow the GC going Canaries to Caribbean.
The Southern hemisphere has a lot less land so maybe sailboats GC routes make more sense there?
View attachment 171095

Going Canaries - Caribbean I was forced by southerly (!) winds to start heading almost due west several days earlier than I wanted... at that point the great circle route did still matter.

 

[Paul1962]

...and they walk among us.....

More to the point - they procreate!

 

[pyrojames]

This is the England to NZ one, I think: Amazing map proving you can sail from Britain to New Zealand in a straight line ?

It certainly isn't feasible, and may intersect the Amundsen Coast of Antarctica! I'd also be worried about the Falkland Islands and Pete I Øy. I note that they are using a pretty low-resolution world map of dubious accuracy in the Antarctic, too. And, of course, a large part of it would mean sailing through solid pack ice!

You can check possible GC routes on google maps by using the "measure distance" feature. I am currently hitting eastern Russia in my attempts!

 

[Daydream believer]

View attachment 171152

The only reason that they decided to depict the earth as a giant ball is to save space. So it is convenient. If they showed it in its true flat form it would take up so much more room as to be inconvenient.
Simple solution really, but you try telling kids that