Estimating Tree hieghts??

[countrryboy]

Alright folks, bit of a strange 1 for u.

 

Was just wondering if there is an easy way or how everbody estimates the hieghts of their trees before felling.

 

Been a bit closer (althou not majorly close) to a couple of things than i thought i would've been recently, luckily i'm quite belt and braces so had the extra clearance, thank god.

 

When i was a boy, scouts i think (or possibly school?) they had a method for measuring the hieght.

 

Bit hazy on it now but i think u held a twig upright in ur hand, with ur arm oustreched and then walked backwards until the top of tree was inline with the top of the twig.

U them paced it back to get the hieght (+ 4ft or hieght of arm of ground)

 

I'm guessing now it must be some sort of Pythagorus? therum, right angle triangles etc, but my school days/triganometry are a long distant memory.

 

Does anyone know wot i'm talking about or does it make sense?

And does the length of stick u hold up matter?

 

Cheers in advance

[hedgesparrow]

Alright folks, bit of a strange 1 for u.

 

Was just wondering if there is an easy way or how everbody estimates the hieghts of their trees before felling.

 

Been a bit closer (althou not majorly close) to a couple of things than i thought i would've been recently, luckily i'm quite belt and braces so had the extra clearance, thank god.

 

When i was a boy, scouts i think (or possibly school?) they had a method for measuring the hieght.

 

Bit hazy on it now but i think u held a twig upright in ur hand, with ur arm oustreched and then walked backwards until the top of tree was inline with the top of the twig.

U them paced it back to get the hieght (+ 4ft or hieght of arm of ground)

 

I'm guessing now it must be some sort of Pythagorus? therum, right angle triangles etc, but my school days/triganometry are a long distant memory.

 

Does anyone know wot i'm talking about or does it make sense?

And does the length of stick u hold up matter?

 

Cheers in advance

was out with a tree surgeon he got a stick elbow to wrist held it up in front of him walked back untill bottom and top was at both ends said it drop there it dropped right in that spot.

[Shane]

Thats about it - get a stick the same legth as your arm (eye to holding fingers).

Hold arm out horizontal, hold stick vertical (90 degrees to arm).

Walk back/forwards till top of tree lines up with top of stick and felling point lines up with bottom of stick.

 

As near as dammit you are standing where the top of the tree will finish, if the felling goes to plan.

 

It's a right angle triangle with a 45 degree slope upwards (1 in 1 or 50%).

 

As its a right angle triange then Pyrthagorus' theorem applies.

[Stephen Blair]

That's how I do it and then fell it on a Ford Fiesta 2 doors down

[countrryboy]

Cheers folks, thats brilliant.

 

I knew i wasn't too far away but just couldn't mind the finer detail.

I figuered it must be a right angle triangle thing but just didn't know if the size of the stick would of affected it or wot size it was meant to be.

 

Must admit my memory is pretty hazy but i can't remember the stick being as long as mentioned above, but it was a long time ago and my brain has been pickled in the meantime

 

Cheers agian, an;t wait to go out and try it now:001_smile:

Edited April 10, 2014 by countrryboy

[gand]

As said use a stick hand to shoulder length and walk back will give approximate height, there is electric gizmos to do it aswell

[muldonach]

There is or was a little plastic device available - a cheap relascope - which you held up to your eye and walked backwards until one pin was lined up with the tree base and t'other on top of tree - you were standing at the height of the tree away from the base.

 

Same idea as the stick

[detritus21]

I have a height measuring app on my phone. Failing that I just look at what is the approx height of a man and use that as a guide. Tends to over estimate but prefer that than under estimate and drop it onto something

[aquatoo]

If I followed the method given here, wouldn't it depend on the length of the stick? If it was a two foot stick I'd end up further away than if I used a three foot stick, wouldn't I?

 

Maybe I'm missing something. The way I was taught in the scouts was to get a stick walk back until the stick ends were level with the base and the top and then spin the stick to the horizontal, keeping the bottom end still in line with the base - thus forming a right angle triangle - note where the end of the stick appears on the ground and then measure or pace it off.

[richy_B]

I'm guessing now it must be some sort of Pythagorus? therum, right angle triangles etc, but my school days/triganometry are a long distant memory.

 

 

I am a little geeky when it comes to these things but mathematical way of working it out is pretty straightforward.

 

Imagine a triangle (lets assume the tree is pretty much upright/without lean). You want to know the height side of the triangle or the 'opposite'. What you can easily work out from the ground is how far away from the tree you are standing by pacing backwards. This gives you the 'adjacent' length. From the the point you are standing you measure angle by eye between the base of the tree and the tip. Just use a simple 99p school protractor and a bit of string/pencil. Then using a calculator type in the angle you measured then press 'tan'. You then multiply this number by the distance you are standing from the tree. Add on your own height and you've got a roughly calculated height of the tree.

 

So as an example - I pace 20 metres from the base of a tree. I hold the protractor flat at my eye level and look at the top of the tree. Lets say the angle is 50 degrees. type in 50 press 'tan' gives me 1.91 which i times by the 20 metres giving 23.8 meaning, I am 1.94 so add together you get a tree that is 25.8 metres tall. Sounds complicated but you can do it in a minute.

 

This calculation is based on a right angle triangle but it will give you a pretty accurate figure. If you are on a significant slop the maths starts to get a bit trickier.

Edited April 11, 2014 by richy_B