Elevation/slope

[Jebediah]

How do you determine elevation/slope? I am thinking about taking a shot at tubing. I have a stretch of woods with gentle slope, maybe 500 feet length and 20 feet of drop from one end to the other. But this is a wild guess. How do you actually measure this? I did search this forum, but didn't come across answer. Thank you.

[maple flats]

I use this : http://www.gpsvisualizer.com/elevation With this IF you can identify the exact location on the map, it will give you the elevation to the foot. It all depends on how well you can identify the location on the map. When I use it, I go to satallite view and zoom in as far as it will go.

[lpakiz]

Some automotive-type GPS's will give elevation. Probably not all that accurate, but it's a place to start, especially if you have good slope.

[unc23win]

Determining slope is not nearly as hard as some people make it sound. You can get ideas like Flats said by looking at satellite images. If you have a natural slope already all you have to do is determine a height of the line and maintain the slope throughout the run. There is a really cool Clinometer app (SeeLevel) I use on my iPhone and it works pretty darn good for me. The app uses the gyro whatever in the phone so it works without service or gps. The most important part about slope is making sure you can maintain the same slope throughout the run and making it so it is easy to adjust.

[BreezyHill]

How do you determine elevation/slope? I am thinking about taking a shot at tubing. I have a stretch of woods with gentle slope, maybe 500 feet length and 20 feet of drop from one end to the other. But this is a wild guess. How do you actually measure this? I did search this forum, but didn't come across answer. Thank you.


11986

These are the tools I use to get my lines set at grade.
For the most accurate when working with 1% slope (1'/100') I use the transit level. This is a two person task and radios are great so you don't have to yell thru the woods.

Next is a Clinometer that has a rotating indicator that will read the slope from -150% to 150%. This is great for checking slope when deciding where you want to lay your lines. Nice to have another person so you can aim at a point on their body that matches your eye level for most accurate readings.

This is an adjustable bubble clinometer. Set the desired slope on the side and when the bubble is centered on the site line you are at desired slope. Great for setting the lines, painting or marking trees as to where to attch the line to trees or setting your end and start j bolts.

All are available on ebay from time to time at great prices. A transit pole graduated in 10ths is a great tool with the transit level instrument if running elevated lines or ladder lines.

NOt pictured is a range finder. With the transit a range finder will help to set the unit at a desired slope so you can mark trees. Or for distance when running the transit pole for compensating for distance.

I tried the I phone's clinometer app and it varied to much for accurate design of 2% or less. Not bad at 4% and above.

I prefer to use a green flag tape for setting where mains will go after I have orange flagged taps. Bisecting a group of taps uses less tubing than a set distance interval thru the bush in my case. Set the tape where the line is to pass.

I use J bolts at the terminal ends to attach a length of High tensile wire and a rapid tightener to tighten the tubing. If using support wire the wire is also attached to the J bolt. These are also available on ebay. Some places call them drive rings.

Good Luck!

Ben

[Jebediah]

Many thanks folks, lots of useful info. Tempted to run out and try some of this stuff right now. But it will have to wait till January. Mass archery starts in two weeks, and I will get heck from my boys if I go out there now and stir it up. This is a dual-use piece of woods. Thanks again!

[maple flats]

While I have lots of toold for slope, I generally use a sight level like this one: http://www.ebay.com/bhp/sight-level
The maple dealers sell them for $30 and up. With a little practice you can run lines quickly. First I use the GPS visualizer: http://www.gpsvisualizer.com/elevation to plan the system, but then in the field I use the sight level. It can easily be done alone. Just start by tying a marking ribbon at eye level on your starting point. Then walk as far as you can see that ribbon but sometimes shorter intervals works better, then hold the sight level up and line it up with the ribbon, you can then read the slope either up or down, each line is 2% with the bubble centered on the longest stadia line which is in the center. While 1% can work, it requires far more accuracy and support. Try to get between 2 & 4% slope, more can cause unwanted turbulence. Ideally, the mains should run slowly rising along the contour lines, and the laterals (5/16 or 3/16) should be as steep as you can get them. If using 5/15 strive for 5-7 taps per lateral and keep the lines to 100' or less. If 3/16, you can go 2 or even 3x that and try to get 25-30 taps max on a 3/16 lateral. Once you layout the mains with ribbons a eye level, lower each to about 3'or so, by measuring down and placing a new ribbon or moving the eye level one. The only reason to first set them a eye level is because it is easier and faster the set the ribbons that way and then measuring down. While your marker trees may all start at eye level, since the land it likely not a perfect constant slope, some places the main may be closer to the ground and in some spots it could even be over your head. simply adjust that by going up or down along the slope to try to keep it in that 2-4% range. In some places, even 2% is hard to get, just do what you must. Try to eliminate sags, they reduce sap flow.