Compass Tricks: Judging Height and Distance
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- Опубликовано: 10 июл 2024
- Learn more compass tricks and other bushcraft skills in Mike's new book "21st Century Bushcraft".
For more information or to order Mike's book, please visit us at:
bushcraftnorthwest.com
Wonderful use of a right isosceles triangle. I would never have thought of that. Outstanding!
Thanks so much and glad you're finding the information useful! ML
Awesome dude! Thanks so much. Just what I’ve been looking for.
This is great! I was measuring tree heights last year and I wish I had your simple formula chart then. Great stuff Mike!
This is just what I was looking for to measure for a zipline installation! Good stuff!
Yay!!!! Thanks for putting up a video! It's been a long time. Great information!
Thanks Andrew, it has been a while and I'll try to do another very soon. Take good care and thanks again for watching.
Excellent video and information. Thank you.
Using trig in the field! Awesome video!! It is always amazing how many applications trig has that are not taught.
I put a circular sliderule with a tangent scale on the back dial of my compass. It makes the math easy.
Instruction to make one please
After an hour of looking, I finally found a good trigonometry real world example video. Thanks for making this!
So glad you enjoyed it and thanks for the comment.
For the river crossing, if you adjust the bearing by 45 deg and walk parallel to the water edge until your azmuth lines up, you'll have the exact distance to the opposite bank.
i know it is kinda off topic but do anybody know a good website to stream newly released series online?
@Bryson Corbin Yea, I've been watching on FlixZone for months myself =)
@Bryson Corbin thank you, I signed up and it seems to work :D I really appreciate it!
@Reginald Declan you are welcome =)
Excellent video Mike!
Hi Craig, thanks buddy and hope all is well!
slick trick Mike
great info thanks
great tutorial, good for rough estimation. One point that you should have mentioned is that the angle from you eye level to nest is different from the ground level to nest. In case of a small difference in between your height and nest height. the result length of tree will not be right.
Nice knot.
Using 45 degrees, you can also measure the height with a clinometer in the inside of the housing (if available on the compass). Position oneself at a place where you do a reading of 45 degrees on the clinometer, the distance to the object is the same as its height. Then measure the ground distance from that point to object, which you can do with pacing (if you know your pacing) or other. And as mentioned on the video, if using a clinometer, you need to add the height the reading was taken from too. Benefit: no trigonometry table necessary, and bit more accurate (as its a 1:1 ratio). Caveat: sufficient distance is required.
If you don't have a compass, you can use the sun and a tall object (yourself/ or a stick at least 1m long), to find a 45 degree. Using a stick, stick it to the ground vertically. Draw a circumference of the sticks height from the ground. When the stick's shadow hits the circumference, you've got an approximate 45 degree angle.
Well done Mike, this is a big help. Actually looking a tree I have to take down in my yard and want to make sure I have the clearance. You may not do vids often but they're always well done.
Thanks and I'll try to keep the momentum and do regular videos. Time seems to be flying by lately!
Never enough time and it seems to get worse the older I get. Printed and cut out your formula and mounted to my vintage Silva 15. Just did some height testing and sure came in handy! Thanks again.
FANTASTIC!!!
Thanks and I'm glad you found it helpful.
Thanks
Where you been? Great videos was happy to see you had posted a new one. Thought maybe you had got lost and didn't have your compass with you! :)
Ha! No, nothing that dramatic...just busy teaching and working on some new product designs. Hope all is well and I'll try to make more regular postings. Thanks and take good care.
I learned that in the Boy Scouts back in the late 60's, don't know if they still teach basic Trig in the scouts today.
Basic math in the real world! Thanks!
I love the ability to use my silva rangefinder compass to determine height and distance. Here is how I would use the info in this video to help determine distance to a target. By the way, if you are using a compass to navigate then bring along a little notebook and pencil to record notes, draw self-maps of the area you are hiking in and to make your calculations. Get good at visually estimating pace counts to your waypoints so you don’t have to physically walk and count those paces (or use a rangefinder like this one www.amazon.ca/gp/aw/d/B07RNNGT3C/ref=ppx_yo_mob_b_inactive_ship_o1_img?ie=UTF8&psc=1). Record the TAN chart mentioned in the video into your notebook. Don’t tape the chart to the back of your compass. Nah, it’ll just fall off when you’re not looking.
Here is my modified procedure to estimate distance using my Silva Rangefinder compass and the TAN chart mentioned in the video.
Draw a right triangle in your notebook. The point of the triangle where the 90 degree angle is will be where you are standing now. The point straight up will be your target. We want to find the distance from where we are standing to that target. The other point to the left or right will be where you will walk to for when you shoot a second bearing to the target. It is also where the angle is that you will look up in the TAN chart.
In trigonometry, the TAN of an angle = opposite side distance /adjacent side distance of a 90 degree triangle. We are going to be using our compass to figure out that angle and we will be using a pace count to determine the adjacent side distance. Then we calculate the opposite side distance using the TAN ratio from the chart which is what we want to find out.
Stand in front of an object you can sight the target from and that you will be able to see if you walk on a line 90 degrees from the target line. This is the base object. We will be determining the distance between the base object and the target object.
From the base object shoot a bearing (red in shed) to the target object. Record the bearing in your notebook.
Holding the compass stationary and with red in the shed , move around the compass baseplate so you can sight down a short side of the baseplate to sight on another object on a line perpendicular to the target line to walk on. During this process keep red in the shed. Sight an object on the perpendicular line.
Walk out on the perpendicular line pacing the distance to some point where you can see both the base object and the target. The farther you walk, the more accurate the result will be. Multiples of 100 paces will keep the calculations simple.
Sight back to the base object using a short side of the baseplate and keeping red in the shed. Adjust your position if necessary to ensure you are still on the perpendicular line. Record this paced distance in your notebook.
From your new location shoot a bearing to the target (red in shed). Record the bearing in the notebook.
Determine the Angle
1. Subtract the larger bearing from the smaller bearing.
2. Subtract some multiple of 90 from the previous calculation so that the result is between zero and 90. This is the angle.
Look up the TAN ratio in the chart for the angle.
Multiply your distance on the perpendicular line by the ratio. The result is the distance from the base object to the target along your first bearing.
Example:
Bearing 1, base to target = 340
Bearing 2, perpendicular line to target = 40
Distance on perpendicular line = 100 paces
Angle
340-40=300
300-(90X3)=30
From the TAN chart for an angle of 30 the ratio is 0.58
Distance from base object to target
100 paces X .58 = 58 paces
At the moment i am stock inside due to a hip problem so time to watch some instruction.
I do it on paper and works out well..at least with the river.
Just a thought or maybe you have a alternative and dont want to use a stick etc for measuring the height..as i only have a simple base compass....
With a hammock we use the 30 degree to hang up your suspention..but if you make your hand like a 45 degrees pistol...would that work as well to measure the height??
Just wondering..
Anyway maybe your thoughts/experience about it!!
Well dont have here a profile but on Fb kayak cobber
Thanks and greetings from Holland
Hi and thanks for the comment. The best way if you don't have a compass clinometer is to use a stick that's as long as your arm. By holding the bottom of the stick upright and at arms length you will create a 45 degree angle from your eye, to the top of the stick, to the top of the tree. At this point you are as far from the base of the tree as it is tall. Hope that helps and I wish you a speedy recovering from your hip problem. Take good care. ML
Hey Mike: Can you give the brand name, the item description, and where you got that compass/inclinometer? Thanks. Very interesting vid!
Hi Robert, the compass I used is a Suunto Global MC-2G which is available on our website here.
bushcraftnorthwest.com/products/suunto-mc-2g-global-compass
You can download the formula here:
bushcraftnorthwest.com/p/links
Thanks for watching!
I always think
if you stop at mountain before ascending, mark on map then draw line on map from the mark that you stop to top mountain and from top to bottom of the mountain and from bottom mountain to your mark you will get triangle of 90 degree then use formula of 90 degree triangle which is
squar(n) =(squar n +squar n)
Great video but do you have metric formula instead imperial?
Hi Tom, the formula is actually the same because it is a ratio. You would just use meters instead of feet or yards to get your distances. Hope that makes sense and thanks for watching.
well ill have to watch again, because that was about as clear as mud to me, lol
same here
Do you recommend a certain brand clinometer?
HI David, thanks and I'm glad you enjoyed the video. Any clinometer will work , but as far as compasses go I prefer Suunto. They are the best quality I've used. The compass in the video is the MC-2G Global.
ok so u sight off the top edge of the compass? not the sighting hole in the middle?
Yes, that is correct when using the clinometer to determine height. In order for the clinometer to work with gravity, the compass must be on its side so there is no way to use the sighting hole. However in the river crossing example, the compass is held level in which case the clinometer does not work. The magnetic needle and sighting hole are now used instead. Hope that helps. It's much easier to demonstrate in person but I did the best I could with the video format. Thanks for watching.
thank u@@BCNW1
but what are the ratios and or formula?
Hi Cody, the formula got moved here when we updated to our new webpage. bushcraftnorthwest.com/p/links
Hope that helps and thanks for watching.
an alternative for measuring hight is to use the standard compass and a plumb line
Hello, so are you essentially using the compass as a protractor?
Michael Lummio i was referring to the fact that most compasses do not have clinometers built into them; so as an alternative for it, using an external plumb line can accomplish the same thing, thus providing a similar result
Algorithm 4u 👍🙂
ok now u say, mark off 10 feet from base of tree, so mmm not 10 ft from directly under nest?
Yes, that's correct. In the video example, the nest was directly above the trunk which is why I walked off from base of the tree. If you wanted to measure the height of a nest located on a limb away from the trunk, you'd walk off the distance from underneath the nest.
Thank you
ya just not understanding the river crossing aspect of the video, but hey, im hard headed
It's definitely a bit difficult to teach over a video with limited production capabilities. I recommend setting up a small scale scenario in your house or yard and breaking it down step by step. You have to do it real world with a compass in hand, otherwise it's hard to wrap your head around for sure. Let me know if you have any questions or get stuck and thanks for watching.
It's called trigonometry. Memorize the unit circle. It's that easy.
I am Australian and that means meters.... I am thumb and close one eye bloke.
Christmas tree jokes should ensues... Alas.... I have hair that is square and weighted
Brain being used!
👍🏻
you're not making it clear buddy for the audience
Sorry, did the best I could in the time frame. Definitely easier when I teach this in person but I'm happy to answer any question you may have. Hopefully you'll enjoy the next video more. Thanks for the honest comment.