Trees are quite strong. When we do demonstrations by breaking
equipment during cave rescue classes, we use trees as anchors
and a truck with an electric winch attached to one tree. Some of
these things break at several thousand pounds force. (We measure
the force with a load cell.)
The basics for tree anchors:
(1) Make sure the tree is alive and healthy.
(2) Wrap the tree with a tarp or heavy cloth to protect its bark
from damage.
(3) Then wrap it with 2" nylon webbing at least 3 times. Use a
water knot to join the webbing. Leave the knot facing the load
and pull the rest of the loops out to a carabiner or quick link
rated for the expected load. This arrangement gives you a chance
of being able to untie the know when you are finished. (2"
tubular webbing is rated at 4000#. If you pull two loops, that
is 4 strands and 16000#. Derate by 50% for knots, bends around
carabiners etc and get 8000#.)
(4) If you are breaking things, such as #8 copper wire, cover
them with blankets to minimize the danger of having them snap
through the air.
(5) Keep everyone far enough away so flying wire won't hit them,
or keep them in a closed vehicle.
73 Bill AE6JV
On 2/11/16 at 6:34 AM, eda...@law.du.edu (Dauer, Edward) wrote:
I wondered what 700 or 800 pounds of shear force would do to an
automobile frame, assuming attachment to a suitable bolt
somewhere. Or would the tree fall over first?
-----------------------------------------------------------------------
Bill Frantz | Security is like Government | Periwinkle
(408)356-8506 | services. The market doesn't | 16345
Englewood Ave
www.pwpconsult.com | want to pay for them. | Los Gatos,
CA 95032
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