Foo - Bearing and course

I got this assignment in trig today, a worksheet on bearing and course.
She said we all were supposed to have learned this stuff, and said htis should just be a review. But I've never seen this, I don't go out to sea very often...
Here is a sample problem:
A steamship is 23.3 due south of Pequanic Lighthouse. From Pequanic Lighthouse, the bearing of Wontauk Lighthouse is 90 degrees. The distance between the lighthouses is 26.6km. Find the bearing of Wontauk Lighthouse and the steamship.

When they say "due south 23.3km". Does that mean the steamship is 23.3km "below" the Pequanic Lighthouse if we were draw this on an XY vector plane?

right triangle

side opposite is 26.6
side adjacent is 23.3

find theta

yes the steamship is below the lighthouse, bearing 180 degrees from lighthouse, bearing of zero from perspective of steamship

Can you tell me what 'bearing' is?
The only bearing I am familiar looks like this:
http://www.welsch.com/gallery/3d/Kugellager_404.jpg

oscar had a headache over algebra

sin(theta)=O/H
cos(theta)=A/H
tan(theta)=O/A

plug in the numbers, solve for theta

I know all that stuff already.
But what is bearing? Literally, what does bearing mean, in nautical terms?

if you know this already then WTF is the problem?

get out a calculator

I know how use trig functions. I just need to know what they mean by "bearing of 90 degrees". or whatever. WHAT is bearing?

Wikipedia is your friend. (http://en.wikipedia.org/wiki/Bearing_%28navigation%29)

I did look at that. I didn't find it very helpful.

I know all that stuff already.
But what is bearing? Literally, what does bearing mean, in nautical terms?

bearing means direction to a target relative to your position

So say I was walking down the +X axis. Then another person was facing and walking at 275 degrees relative to the Y axis. Y axis being the 0 degrees, our reference. So my course is 90 degrees. And, the bearing of the other person and myself is 185 degrees?

bearing, in nautical terms, is directional measurement off a compass point. These days, most folks use GPS instead.

I think I will remember to stick with GPS, forgo this crap of an assignment, and calculate the strength of electric fields for physics instead :)

So say I was walking down the +X axis. Then another person was facing and walking at 275 degrees relative to the Y axis. Y axis being the 0 degrees, our reference. So my course is 90 degrees. And, the bearing of the other person and myself is 185 degrees?

there's no Y axis, just a compass and distance, that is how navigation is done, by using bearing, course, speed, and time you can know quite well where you are, old fashioned dead reckoning

but doing it your way, ya, 185 degrees

My teacher is fairly old fashion, so I guess that is consistent. I think my physics teacher would tell us to use GPS instead :p

last GPS I used gave an output in bearing and distance to next waypoint :) plus kept track of your current and average speed

someone isnt gonna tell you to walk 1 mile down an x axis unless they know how that axis is oriented, but they can tell you to walk 1 mile on a heading or bearing relative to you and you will know which way to go :)


I use it all the time in silent hunter 3 and flight sim 2004

I got this assignment in trig today, a worksheet on bearing and course.
She said we all were supposed to have learned this stuff, and said htis should just be a review. But I've never seen this, I don't go out to sea very often...
Here is a sample problem:
A steamship is 23.3 due south of Pequanic Lighthouse. From Pequanic Lighthouse, the bearing of Wontauk Lighthouse is 90 degrees. The distance between the lighthouses is 26.6km. Find the bearing of Wontauk Lighthouse and the steamship.

When they say "due south 23.3km". Does that mean the steamship is 23.3km "below" the Pequanic Lighthouse if we were draw this on an XY vector plane?

Bearing is the direction to your target, but may be either true bearing, magnetic or relative bearing. True bearing is the direction from you to your target in reference to the true north pole. Think lat/long where steering 180* "true" takes you straight down a line of longitude. Magnetic bearing is the direction from you to your target in reference to the magnetic north pole. So, steering 180* magnetic would take you on a course over the ground of something other than due south. Relative bearing is the absolute difference between you and your target. So, if something is behind you, it's relative bearing is 180*. But, if you're facing due east, your (mag or true, depending) bearing to your target is 270*.

Course is your path over the ground. It's affected by wind, currents or other factors. So, say you want to get to a waypoint that's 090* magnetic from your current location. You have a southerly current affecting your ship. I'm not much of a mariner, so I don't know what kind of correction factor you'd need, but something less than 090*. If you were flying, you'd "crab" into the wind some amount, depending on your airspeed. For example, to achieve a course of 090* magnetic, you might fly a magnetic heading (or bearing) of 083*. If you've calculated your drift correctly and are countering it, your bearing to the point remains 090* until you reach it.

Confused yet? As others have pointed out, your problem is a simple trig problem and has nothing to do with courses. Just bearings and distances.

The trig part is easy, I use trig everyday. I think I know what bearing is now, I will tackle it tomorrow.

Bearing is the direction you're pointing, measured in degrees clockwise from north.

Bearing is the direction you're pointing, measured in degrees clockwise from north.

not necessarily...

not necessarily...

generally speaking.

Bearing is the direction you're pointing, measured in degrees clockwise from north.


nope, that would be your course or heading

It can also be the direction in degrees of an object or other ship relative to your course.

So say I was walking down the +X axis. Then another person was facing and walking at 275 degrees relative to the Y axis. Y axis being the 0 degrees, our reference. So my course is 90 degrees. And, the bearing of the other person and myself is 185 degrees?

No. I'm presuming that your problem is referring to true bearing. True north is always 0 degrees. Bearing is the compass bearing relative to the stated reference point.

<edit> Skiahh has an accurate description - not surprising for a Naval Officer and a pilot. :)

It can also be the direction in degrees of an object or other ship relative to your course.

That would be relative bearing.

Finally, my experience on Naval vessels is applicable to civilian life. :o

Bearing is the direction you're pointing, measured in degrees clockwise from north.

Actually, as an absolute statement, this is wrong. Bearing is the direction to or from something based on one of 3 references: true north, magnetic north or yourself.

The direction you're pointing isn't a bearing, it's just a direction. Or a heading. If you're moving, it's a course, too.

Bearing is measured in degrees with clockwise being the increasing direction, but it's not always from north. Say you're facing east and you want to know the relative bearing of something directly to your right. You could say it's bearing 180* or you could say it's 090. Depends on your point of reference.

Obviously both parties need to know the reference when giving a bearing.

nope, that would be your course or heading

No, he's right. Bearing is the direction you are pointing. Course is the direction you are traveling, which, with wind and current, is generally not the same as your bearing.

Actually, as an absolute statement, this is wrong. Bearing is the direction to or from something based on one of 3 references: true north, magnetic north or yourself.

The direction you're pointing isn't a bearing, it's just a direction. Or a heading. If you're moving, it's a course, too.

Bearing is measured in degrees with clockwise being the increasing direction, but it's not always from north. Say you're facing east and you want to know the relative bearing of something directly to your right. You could say it's bearing 180* or you could say it's 090. Depends on your point of reference.

Obviously both parties need to know the reference when giving a bearing.

Ok, ok. You got me.

In the context of phantomcow's problem, though, I think they're looking for degrees clockwise from north.

Unless your Capt Kirk.

No, he's right. Bearing is the direction you are pointing. Course is the direction you are traveling, which, with wind and current, is generally not the same as your bearing.

Bearing could be the direction you are pointed or heading. The meaning of the word depends heavily on the context it is used in.

No, he's right. Bearing is the direction you are pointing. Course is the direction you are traveling, which, with wind and current, is generally not the same as your bearing.

Bearing is NOT the direction you are simply pointing. Bearing is an angular relationship between you and something else, relative to a common reference and not simply the direction you are facing or heading your are taking.

I will be certain to use GPS when I go out to sea :).
I did end up solving that worksheet today though, it's not so bad when I figured out what bearing is.

Bearing is NOT the direction you are simply pointing. Bearing is an angular relationship between you and something else, relative to a common reference and not simply the direction you are facing or heading your are taking.

We need a good set of parallel rulers, dividers and plotting paper. Time for maneuvering board 101 lessons. :D

I will be certain to use GPS when I go out to sea :).
I did end up solving that worksheet today though, it's not so bad when I figured out what bearing is.

You have to be careful... GPSs can die, be jammed or whatever. You still need to keep a manual plot.

We call people who lose their basic navigation skills INS (Inertial Navigation System) or GPS cripples.