View Full Version : Another Dumb Question



north
08-10-2008, 05:25 AM
ok, here it is. Is there a formula or converter to take something like S 38 degrees E 15 minutes and turn that number into a bearing heading. I tried fizzycalc and it didn't seem to work on this format. I tried using my compass to get the answer, but not sure if I'm right or not and want to check the result. I come with a number like 138.250 and a return heading of 318.250. Am I in the ball park, or still out in left field, lol. Thanks for putting up with all these questions I have. TC all

brdad
08-10-2008, 07:56 AM
You are only dumb if you don't ask when you don't know, bearing and heading gets confusing to many.

First of all, bearing and heading are usually two different sets of numbers.

Heading is the direction you are going at any given moment. You may want to be going North (0), but the road you are going may currently be NE (45). This makes perfect sense while caching, as it's rare to be able to go in a straight line to the cache.

Bearing is the direction you need to go to get to where you are going. If you know point A and point B, the distance tab in FizzyCalc will give you a bearing.

If you are navigating to a location, you need to re-adjust your bearing unless your heading stayed perfect, which probably has never happened.

138.250 and a return heading of 318.250 are perfectly valid heading/bearing values, but without knowing both sets of coordinates I can't tell you how correct they are.

0 or 360 are North
45 is NE
90 is E
135 is SE
180 is S
225 is SW
270 is W
315 is NW

Now, to throw another twist in to mix, you have to pay attention to whether you want magnetic north or true north. Magnetic declination is the difference between the two. Currently for Bangor this number is about 17 W. This means that if you were using a compass, the arrow would be pointing 17' W of True North.

If you explain more what numbers you have to work with and what you are trying to accomplish, maybe I can help more if you need it.

darterkitfox
08-10-2008, 08:26 AM
Heading is the direction you are going at any given moment. You may want to be going North (0), but the road you are going may currently be NE (45). This makes perfect sense while caching, as it's rare to be able to go in a straight line to the cache.


Boy, Brdad, you haven't done many of the new caches in Lewiston/Lisbon lately have you. You can't get a straighter line than to all those guardrail micros.

brdad
08-10-2008, 08:43 AM
Boy, Brdad, you haven't done many of the new caches in Lewiston/Lisbon lately have you. You can't get a straighter line than to all those guardrail micros.

Well, I am of course talking about caches you would even care knowing the distance and bearing. If your goal is 15 feet from the car, it's hardly worth calculating a bearing. Heck, it's often hardly worth opening the car door. ;)

But, lets keep that for another thread.

north
08-10-2008, 11:19 AM
All I have is that number for a direction, and the distance is 1550 feet through dense woods and underbrush, and yes the direction given was for true north. Hope this helps you, so you maybe can help me, lol. The gps see will give me a bearing, but won't display that S 38 degrees E 15 minutes heading i was given. Maybe I should just stay in the car, lol. Thanks for reading this.

north
08-10-2008, 11:23 AM
All I have is that number for a direction, and the distance is 1550 feet through dense woods and underbrush, and yes the direction given was for true north. Hope this helps you, so you maybe can help me, lol. The gps see will give me a bearing, but won't display that S 38 degrees E 15 minutes heading i was given. Maybe I should just stay in the car, lol. Thanks for reading this.
Oh, another thing, I was never given an ending value for this thing, I guess I'm supposed to stumble on this "thing" at around 1550 feet, huh?

brdad
08-10-2008, 12:26 PM
Ah...

You are looking for a projection. With a projection you take your starting point, along with the distance and bearing from that point, and from that you can calculate the other set of coords.

You can do that using the Projection feature of FizzyCalc. Just enter in your posted coods, and the distance and bearing and it will give you the coordinates for the cache.
For example, with a starting point at N 44 47.538 W 068 46.333. You'd enter under the "Point" section of FizzyCalc. And, you'd enter the distance, we'll say 750 feet, in the "Distance" section. And finally, you would enter the bearing, lets say NE, or 45. We then click the Go button and get a final coordinate of N 44 47.625, W 68 46.210. I usually use the "High Accuracy" calculations - generally unless you are projecting many miles, this will not make a lot of difference.

*************
Now, two more methods of projection using your GPS instead of FizzyCalc...

1.Many GPS can do projections. You will have to look at your manual to be sure and to see any limitations. Usually you can enter a distance and a bearing, but often you are limited in increments of .1 mile or 528 feet, which would be 34 feet off if you need to project 1550 feet.

2. If your GPS does not support projections, or does not support the distance you need to project, there is still a fairly easy way to accomplish a short projection. If it isn't already, change your GPSr to display bearing and the distance. Also make sure it is set for True, not magnetic North. Calculate a reverse bearing by adding or subtracting 180 from the given bearing. With the GPSr pointing to the starting location, walk away from that point trying to maintain the reverse bearing and working towards the the specified distance. When you get to the specified distance and the reverse bearing is correct,you should be near the correct location. Essentially with this method, you are trying to walk away from the starting position the specified distance and bearing instead of walking toward the final. Hope that makes some sense.

brdad
08-10-2008, 12:51 PM
I am just realizing the problem with the S 38 degrees E 15 minutes heading you were given. Can you post the GC# of the cache so I can see the context that it is used in? It sounds like they are using quadrant bearings, but I don't think a quadrant bearing should be written quite the way you are posting it.

brdad
08-10-2008, 01:21 PM
Quadrant bearings do not use 0-360 as most of us are accustomed to. Instead, they specify up to 90 E or W of N or South. So, Northeast (45) would be N45E, and Southwest would be S45W. N90E and S90E would both be East.

S 38 degrees E 15 minutes, if it were written the way I think would be correct (Anyone that knows different speak up!) would be S3815'E. since there are 15 minutes in a degree, we could also say S38.25E. If we take 180 (Which is south on a typical compass) and subtract 38.25, we get the azimuth we need for our compass bearing, or 141.75.

Hopefully that helps if it is a quadrant bearing. If you need a visual, I can draw something up.

This could make a good article if I had time to do so....

Sabby
08-10-2008, 01:42 PM
I have never seen it written this way
S 38 degrees E 15 minutes but have seen it written in this form "S 38 degrees 15 minutes E" which I thougt meant to head 38 deg 15 min east of due south or on a heading of 141 deg 45 min.

Check my math brdad.

brdad
08-10-2008, 02:56 PM
I have never seen it written this way but have seen it written in this form "S 38 degrees 15 minutes E" which I thougt meant to head 38 deg 15 min east of due south or on a heading of 141 deg 45 min.

Check my math brdad.

Yes, that is correct according to my calculations.

As far as "S 38 degrees 15 minutes E", that looks correct, too - if fact I thought I posted that, but guess I edited it out. It's the same as S3815'E anyway, using words instead of symbols. But "S 38 degrees E 15 minutes" I don't think is in correct format. Glad I'm not the only one.

I converted to decimal (141.75) mainly because FizzyCalc requires it.

north
08-11-2008, 05:37 AM
Thanks for the responses everybody. This is not a cache, but a practice exersize a friend set up for me, so maybe he's not up on this as much as i think he is, lol. The calculations that sabby and bdad are coming up with is what I think I need to find whatever it is I'm looking for. I think my friend is trying to start me off with some practice on following a heading accurately. Maybe what I asked in the first post was not asked correctly by me. I was assuming that azmuth, bearing, and heading are all the same names for following an accurate straight line to a specific point. I was given a starting point (a red ribbon on a tree) and was supposed to follow the S38 degrees E 15 minutes heading and go 1550 feet to whatever is there to find. I appreciate all the comments and help very much.

north
08-11-2008, 05:47 AM
Quadrant bearings do not use 0-360 as most of us are accustomed to. Instead, they specify up to 90 E or W of N or South. So, Northeast (45) would be N45E, and Southwest would be S45W. N90E and S90E would both be East.

S 38 degrees E 15 minutes, if it were written the way I think would be correct (Anyone that knows different speak up!) would be S3815'E. since there are 15 minutes in a degree, we could also say S38.25E. If we take 180 (Which is south on a typical compass) and subtract 38.25, we get the azimuth we need for our compass bearing, or 141.75.

Hopefully that helps if it is a quadrant bearing. If you need a visual, I can draw something up.

This could make a good article if I had time to do so....

I think I'm missing something here. If there are 15 minutes in a degree wouldn't that make the 15 minutes E another degree, and make the S38 actually S39?

north
08-11-2008, 05:48 AM
I think I'm missing something here. If there are 15 minutes in a degree wouldn't that make the 15 minutes E another degree, and make the S38 actually S39?

or would it make it S37 degrees, I am so confused about this, sorry for not understanding.

brdad
08-11-2008, 06:29 AM
I think I'm missing something here. If there are 15 minutes in a degree wouldn't that make the 15 minutes E another degree, and make the S38 actually S39?

Aha, you caught me on this one. there are 60 minutes in a degree, which makes 15 minutes 1/4 of that, or .25. Sorry for that confusion.

I guess I need to write 100 times on the board

There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.
There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.
There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.
There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.................

north
08-11-2008, 06:55 AM
Aha, you caught me on this one. there are 60 minutes in a degree, which makes 15 minutes 1/4 of that, or .25. Sorry for that confusion.

I guess I need to write 100 times on the board

There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.
There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.
There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.
There are 60 seconds in a minute; There are 60 minutes in a degree; There are 360 degrees in a full circle.................

Wasn't trying to catch you brdad I was just confused, lol. Thanks so much for the info.