We recently came across this post on Reddit. It references a YouTube video claiming to have discovered the longest straight line that can be sailed without going over land. The video creator calls it the Cooke Passage. However, we have attempted to recreate it in Google Earth, and it appears that it is not actually a straight line.
We have in the past discussed what constitutes a straight line in Google Earth. In this instance, we are interested in great circles, which is what Google Earth uses by default when drawing a path. However, Google Earth always draws the shorter arc of a great circle, so to draw the longer section of a great circle it is necessary to include at least one more point and then adjust it with care. You know you have got it right if you can draw another shorter path on any section of it and it still follows the same path.
Using the above techniques, and locations shown in the video, we have investigated the Cooke Passage and decided that it does not follow a great circle.
It seems the record for the longest straight line that you can sail is a route from Pakistan to Siberia, which you can read more about here or see it featured in the following YouTube video:
We also came across another interesting, though shorter route that goes from Norway to Antarctica by way of the Bering Strait.
To see the various routes discussed in this post in Google Earth, download this KML file
About Timothy Whitehead
Timothy has been using Google Earth since 2004 when it was still called Keyhole before it was renamed Google Earth in 2005 and has been a huge fan ever since. He is a programmer working for Red Wing Aerobatx and lives in Cape Town, South Africa.
The longest straight line you can sail on Earth ?
Sail all the way around the world to Antarctica without touching land in a straight line ?
–Peio, Marine GeoGarage
Hi Pieo, I manage to create a great circle that works, almost impossible. It grazes several islands, but it works:
Will from the UK says
“Google Earth always draws the shorter arc of a great circle, so to draw the longer section of a great circle it is necessary to include at least one more point and then adjust it with care.”
It’s not quite the same as drawing the longer section of a GC, but you can draw a very good approximation of a complete Great Circle by using the Circle tool.
– Start the circle at the North Pole.
– Drag down until the resulting circle overlies the equator.
– You now have a complete GC that you can move around by dragging the centre of the circle.
– Move the centre of the circle such the the circle itself intersects the two points you would like to connect.
You’ll need to edit the kml code if you then want to remove the small section, and the globe is an oblate spheroid not a sphere, so all representations of GCs are going to be approximate, but this is a good starting point if you want to play with the greater section of a GC.
Start at Cape Horn and sail westwards, but aiming to arrive 1m further south when you get back to Cape Horn. Keep going and you will sail a straight line, slowly spiralling south until you hit Antarctica. This will get you the longest straight line (if not, aim 10cm south…)
Will from the UK says
What you are describing is a Rhumb line / Loxodrome. In terms of spherical geometry, I’m afraid it’s a curve, not a straight line. More info here:
Yes, I know what a rhumb line is, but the article is about the “world’s longest straight line sail”
If I’m on my boat I set the autopilot to a constant bearing of 269.9 degrees and start sailing from Cape Horn. I’m definitely sailing a straight line in my reference frame as the constant bearing never changes.
Mike Sutton says
But your route would NOT be the shortest distance between start and finish. You’d have to use a great circle to get that. You would never be going straight ahead. By locking into a fixed heading, you could go an infinite distance if you start, for example, anywhere on the 60d S line and just stay on it, and you’d never hit land.
The ‘Cooke passage’ : a new world’s longest straight-line sail ?
Mike Sutton says
The one linked in the article looks like someone eyeballed my original solution. It does hit an island off of Africa. I found a better, verified one which is 19914 miles. I explain (with coords) in my facebook post which I’ll copy here.
About 10 years ago I posted a challenge on the Google Earth (GE) forum to
find the longest straight line you could travel over water before hitting land again.
That forum is now archived and no one can post on that thread. But it’s still there for all to see.
I posted under the username Kryten (-after my favorite mechanoid, my standard name on all forums).
My solution was pretty good, and it doesn’t appear that anyone could find a longer path (-my solution was 19820 miles).
Years later I saw it referenced in a UK article and Ken Jennings posted something on it. But nobody ever linked back to that forum.
But now, using Google Earth Pro, I was able to modify it with two great circles that split the
globe, each with a radius of 6225.25 miles (with centers from opposite points on the earth) and have verified the length with these new coords as at least 19914 miles– nearly 100 miles longer!
Here are the endpoints.
25d 20′ 41″ N
66d 33′ 55″ E
59d 45′ 00″ N
163d 22′ 25″ E
Some points in between:
54d 10′ 20.62″ S
3d 4′ 12.91″ E
This is about 17 miles NW of Bouvet Island
28d 21′ 5.77″ S
111d 23′ 17.18″ W
This is about 143 miles SW of Easter Island
You can recreate my line using those 4 coordinates.
It’s very difficult to get a straight line that long in GE. You have to use multiple lines or a path with multiple segments.
My proven solution uses a circle that splits the earth evenly, making it a “great circle”. (Anything that isn’t a great circle isn’t really a straight line– you’d have to constantly veer to the left or right by some amount.)