What is Due East?

[medevicerep]

Oh well, we will get there eventually.

[Dockhead]

Originally Posted by valhalla360

OK, if you want to play with semantics but it's my primary means of determining my heading.

Not semantics at all -- the GPS has no idea of your heading.

It can only tell you your COG, and only if you're moving. Heading and COG are very different things.

For heading you need some kind of compass. A real one at the binnacle, and/or an electronic one in your network. Surely you are referring to heading provided by your network, which comes from your heading sensor (fluxgate etc.). Not GPS?

[wcapital]

Originally Posted by carstenb

certainly a trick question (i would have answered lisbon also). I would contend that unless given more information, "due east" should be defined in regards to magnetic north (a compass being the only way we have of determining direction).

One could argue that "due east" because of the use of the word "due" refers to true north and I might accept that argument - but great circles can't be brought into the discussion IMHO

Thirty years ago I might have agreed (maybe) - but given the preponderance of GPS for navigation (especially among the general public), not to mention gyro compasses - and the fact that "True"....well, literally means true ---- I think true should should be the default assumption.

However, there's lots of arguments and ambiguity, as amply discussed here. The bottom line, were I a contestant who lost the game show (because I did / I would have answered Lisbon also) - I'd be in contact with an ambulance-chasing, sharp-toothed lawyer to sue their asses for fraud! And I'd bet we'd win.....

[Dockhead]

Originally Posted by Our Tyme

As a Quartermaster in the Navy WAY back when(70s), True course would be implied. Therefore the latitude would not change and you would end up in Portugal.

On a side note: Dockhead, They put 2 GPs units (1 forward and 1 aft) on many ships. The difference is calculated to be the actual heading. Not practical on most of our crafts but done none the less.

Just my 2 cents.

Ken

Yes, satellite compasses are very cool. I really want one.

[jwing]

Maybe this will help you see that the TV show answer is correct:

1) take off you sailor hat and forget about compasses, charts, and all other navigational concepts;

2) re-state the question: Assume that you have an arrow that has one magical property - it will keep going in the direction that you shoot it without dropping to the surface of the Earth. Stand on the top of One World Trade Center and shoot the arrow due east. Assuming there is no weather to blow the arrow off course, where will the arrow first cross land?

This flight of the arrow can be easily discerned with a globe that has a great circle ring. Simply position NYC on the ring with the ring leaving NYC due east. Follow the ring across the Atlantic; the first land is Africa.

But who has a globe? By virtue that you are reading this post, I assume that you have a computer, so I can point to the solution on GoogleEarth. Get NYC down to the bottom of the screen. Then double click the N on GoogleEarth's orientation tool up in the top right corner. That puts the bottom horizontal border at 90 degrees to North, or due east. Now drag the earth along to the east, using horizontal border and the sea bottom features to keep the the arrow's flight from wavering north or south. You will run into Africa.

Repeat the exercise to try to get the arrow to Portugal and you will discover that you have to point the arrow quite a bit north of NYC.

[wcapital]

Originally Posted by Dockhead

Not semantics at all -- the GPS has no idea of your heading.

It can only tell you your COG, and only if you're moving. Heading and COG are very different things.

For heading you need some kind of compass. A real one at the binnacle, and/or an electronic one in your network. Surely you are referring to heading provided by your network, which comes from your heading sensor (fluxgate etc.). Not GPS?

Yes....but again, the general public might quite reasonably assume COG is same as "heading" (yes, I know that's not correct - but they also should have defined more precisely what was meant). And, all of us navigators know that on nearly every chart the compass rose shows magnetic variation; and we're taught to always calculate course etc. back to true - since magnetic is...well, variable! I was never in the navy, but as a teenager was taught navigation by a retired navy officer - who did it this way.....

[carstenb]

Originally Posted by wcapital

I'd be in contact with an ambulance-chasing, sharp-toothed lawyer to sue their asses for fraud! And I'd bet we'd win.....

I'd get Dockhead who is both a lawyer and a sharp sailor - by the time He got done with them - they'd be begging you come pick up the money

[Randy]

Navigation is conducted using true courses. If on a small boat, you're using a magnetic compass you calculate the adjustments of deviation and variation and while your compass is telling you your magnetic course; your true course is 090T. I'm surprised how many people including apparently the person who developed the question are getting "wrapped around the axel".

Sent from my SAMSUNG-SGH-I337 using Cruisers Sailing Forum mobile app

[KidSheeleen]

Warning if you go straight in any direction, you will fall off the Earth as it' a flat cube! Beware!!

[leftbrainstuff]

Originally Posted by boatman61

Well.. they reckon the Earth is between 16-19degrees off vertical at present so get a chart and steer 106* and see where you end up..

The frame of reference is geometric. The tilt and magnetic deviation are important when using instrumentation not for route planning.

Senegal sounds like bs. Due east implies non magnetic and same latitude.

The problem is the question is one of those silly academic questions which has missing information. Therefore you need to make assumptions.

I would state the following assumptions before answering:

1) assume east means true
2) frame of reference is a mercator projection
3) constant latitude

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[hamburking]

Originally Posted by TacomaSailor

When I use the Range/Bearing tool in Visual Suite to go Due South from NYC (following the 24W longitude line southward) I am also heading on a bearing of 180T.

It appears Due South and 180T are equivalent, unlike what I found with Due East and the True compass bearing of 65 -vs- 90.

I am so confused?

The answer is Great Circles.

A great circle is the shortest path between any two points on the surface of the earth. It is defined as a plane which intersects the two points AND the centre of the earth.

Lines of longitude are great circles.
Lines of Latitude are not!

Remember, the earth is not flat, like a chart.

[Liam Wald]

And then there is the whole issue of what actual percentage of television content has anything to do with truth. The point of visual media, whether it is a sit-com, a "reality" show, or a news report, has more to do with entertainment than education.
Just because it is on TV...

[Randy]

Hamburking, the question was not "what is the shortest course or distance to some point" it was "If you head 'due east' from New York City , where will you hit land?"

Sent from my SAMSUNG-SGH-I337 using Cruisers Sailing Forum mobile app

[Dockhead]

Originally Posted by jwing

Maybe this will help you see that the TV show answer is correct:

1) take off you sailor hat and forget about compasses, charts, and all other navigational concepts;

2) re-state the question: Assume that you have an arrow that has one magical property - it will keep going in the direction that you shoot it without dropping to the surface of the Earth. Stand on the top of One World Trade Center and shoot the arrow due east. Assuming there is no weather to blow the arrow off course, where will the arrow first cross land?

This flight of the arrow can be easily discerned with a globe that has a great circle ring. Simply position NYC on the ring with the ring leaving NYC due east. Follow the ring across the Atlantic; the first land is Africa.

But who has a globe? By virtue that you are reading this post, I assume that you have a computer, so I can point to the solution on GoogleEarth. Get NYC down to the bottom of the screen. Then double click the N on GoogleEarth's orientation tool up in the top right corner. That puts the bottom horizontal border at 90 degrees to North, or due east. Now drag the earth along to the east, using horizontal border and the sea bottom features to keep the the arrow's flight from wavering north or south. You will run into Africa.

Repeat the exercise to try to get the arrow to Portugal and you will discover that you have to point the arrow quite a bit north of NYC.

That's it! And if you use the Google Earth ruler, it shows a "heading" of 90! Same result in OpenCPN

That makes no sense to me whatsoever. A better navigator than I will have to explain it to the rest of us.

Edit: Here's my guess:

1. I am quite certain that if you literally sail out in your boat from NY harbor and maintain a heading of 90T the whole way across the Atlanta, that you will arrive near Lisbon. Therefore the answer of Senegal is wrong.

HOWEVER, you will not be sailing in a straight line (which would be a Great Circle route). You will be gradually changing course to keep the boat's head pointed 90T.

Therefore:

2. If you were to sail like a Google Maps arrow and head off at 90T, and continue ON THAT EXACT COURSE without turning to keep the compass at 90T, then you might end up in Senegal. You would be sailing a Great Circle route, because any straight line over water, continued long enough to notice it, is a Great Circle route. It's just your compass gradually moves.


So if my guess is right, then the quiz show answer is correct only inside the world of Google Earth, and would not work on an actual vessel with a compass. If you follow the Google Earth arrow and pretend you're a boat, your compass (continuously corrected for local variation of course) will not show 90T except at the very beginning of the voyage. Which is not "heading East" in any nautical sense.

[valhalla360]

Originally Posted by Dockhead

Not semantics at all -- the GPS has no idea of your heading.

It can only tell you your COG, and only if you're moving. Heading and COG are very different things.

For heading you need some kind of compass. A real one at the binnacle, and/or an electronic one in your network. Surely you are referring to heading provided by your network, which comes from your heading sensor (fluxgate etc.). Not GPS?

As I said...Semantics.

There is a technical difference but for most common usage they are the same. If you tell someone you are headed east, they don't ask if that's heading or COG as in most situations, they are pretty close to the same.

Of course, that's the crux of the entire question. They are playing with technicalities to trick the person into giving the wrong answer.