On 11/6/2013 Rob Katz wrote:
> I'm going to be installing a 20' heavy steel mast in my tower (a
> Trylon 72' self-supporting tower). I will be renting a crane to
> lift the mast and drop it from above. What kind of rigging do I use
> on the mast so it can be lifted up vertically, without the sling
> slipping up off the top of the mast?
> Thanks and 73,
> Rob K4OV
There are a few different ways
Probably the way your crane operator will feel the most comfortable is a loop
sling setup in a "choker" configuration
http://www.wisc-online.com/objects/MTL2702/chk1.gif
IF you insist on using knots, DO NOT use polypropylene rope (the yellow stuff)
- too slick, in fact, this is a great place where manilla still works, or
modern climbing ropes
You tie what is called a "constrictor hitch" (similar to a clove hitch, but it
isn't)
http://en.wikipedia.org/wiki/Constrictor_knot
at the balance point, and then a Marline hitch - which is basically a half
hitch, but with the ENTRY of the hitch against the item being lifted
YOU CAN do just the clove hitch with a 1/2 hitch, not QUITE as strong, but
arborists and a lot of riggers use them
http://www.youtube.com/watch?v=QPVd1oZvEFs
--
--
Charlie
www.baysidephoto.com
www.thegallos.com
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