cross sight

[Nish]

This little device came with an order of felling wedges from Tree Stuff. I find the idea, the device, and its directions strange. It is supposed to help me gauge tree height by aligning my sight along the sides of an equilateral triangle. It seems to me that an equilateral triangle will help me gauge my distance from the base of a tree only if my point of view (one corner of the triangle) is elevated to half the tree's height. Thoughts?

 

[monkeylove]

I saw that thing, read the directions and moved on. I just use the old stick method.

 

[Hugalimb]

We were using the sight to get an exact spot when installing cables. I can't rem exactly how to use it but it seemed to work very accurate.

 

[Nish]

If the device is helping anyone measure how far a tree will fall, then I'm guessing its "locator marks" provide the eye with a 45 degree angle, not the 60 degree angle of an equilateral triangle.

 

[Jeff]

I have not played with one of these, so I don't know how they have it set up (I'm guessing such that it does work correctly) but your line of thinking @Nish is correct: If you wish to do this on your own, a level and a 45°-45°-90° triangle works well for determining where the top will hit when felled.

 

[Nish]

Right, Jeff. Even if the cross sight provides its user with the 45 deg. angle, without the level it will tend to mislead, and hazardously so on the downhill slope. The suggested correctives are nearly exactly opposite of what they should be:

"If the user is lower than the tree ground elevation he must move closer to the tree the amount of ground fall. If the user is higher, he must back up the amount of ground fall."​

 

[southsoundtree]

Clinometer app and a measure tape.

 

[Jeff]

Umm, eyeball and practice?? Most tree guys I know that are worth their salt can get it within a few feet just by eyeball. Often before we flop one we'll all go put a stick in the ground where we think the top is going to hit just to see who is the closest. But it also usually means we have a bunch of sticks in the ground within a 5' circle because we're all decent at it and all seeing it the same.

 

[Nish]

I'm very happy with the free clinometer phone app. Even without a tape measure, it seems to be all I need for estimating slope changes, a tree's lean, and how far the tree tip will reach. Thanks for the suggestion southsoundtree.

Tim Ard briefly responded to my product review at Tree Stuff, but I still can't make sense of it. The geometry seems simple.

 

[OasisTree]

I have been using that cross sight for years. Some how they have figured it out. and that little device is very accurate. It is figuring your eye height at 5 ft. You put the cross sight up against your eye, back up till you have the whole tree in the triangle (sight), and where you are standing will be where the top hits, minus the height of your felling cut. I have even found it to be accurate on grades, as somehow the triangle changes. I have one in each one of my trucks, and also keep one with me when bidding jobs.