[TowerTalk] Knot tying

[jimlux]

Charlie Gallo wrote:
> 
> On 12/29/2008 jimlux wrote:
> 
>> K7LXC at aol.com wrote:
> ...snip...
>>> But the even simpler solution is to use nylon  slings. I always
>>> carry 6-8 of them when I'm doing tower work and sometimes I  use
>>> all of them. They are 1" nylon webbing that's sewn together
>>> giving you an  endless loop 12-18" long. You just put it around
>>> the object of interest once  or twice (for heavy loads I'd
>>> recommend at least twice) and pull it thru the  other end of the
>>> loop. Put some tension on it and you're good to go. The more  you
>>> pull it, the tighter it gets. All you have to do to release it is
>>> un-weight it. In the parlance it's known as a choker. Champion
>>> Radio Products  has them and you can buy them at REI - look in
>>> the climbing hardware  department near the carabiners.
>>> 
> 
>> probably a bit pricey for a one shot deal, but maybe you know
>> someone who has them.. soft slings are even nicer (they're a tough
>> fabric tube with unwoven fibers inside).. think of kernmantle rope
>> with a very loose sheath. They're great because they "squish" out
>> where they cross over an edge or something, and they're really
>> abrasion resistant (for the same reason as kernmantle climbing
>> ropes)
> 
> 
>> Also called Spansets
> 
>> http://versales.com/ns/sling_webbing/span_sets.html
> 
>> page 1450 in the McMaster-Carr catalog
> 
> 
> OK - I was never a licensed rigger (disclaimer), but did a BUNCH of
> years of rigging all sorts of stuff (my foreman WAS licensed)
> 
> A nylon sling is great - but not really what _I_ would want for a
> VERTICAL lift of a piece of pipe/tube, but also would not be bad (I
> always worry about nylon slipping, but if you do it up like a
> prussic...)

Exactly, sort of like a choker, except 3 or 4 turns through.  They're 
not all that slippery (it's more like a cordura style canvas covering, 
just softer).


> 
> This is one of those places where a GOOD natural line  (hemp etc)
> works well, and you have an eye in the end to go to your gin poles
> lift line
> 
> The proper knot, at the balance point of the load is a clove hitch,
> tied in such a way that when you pull to the side that will be "up"
> it tightens the knot - you then put a half hitch on the top of the
> load, again, where the weight tends to choke the load - the load goes
> up straight, and when you get it in place, the rope just comes loose

That works well.  I used to tie the clove hitch first, then lead the 
line along the pipe towards the high end, then twist and stick it over 
the end to make the half hitch, take out the foot or so of slack and it 
snugs right up.


> 
> My rigging was not at the heights that big towers were, but I've
> lifted lots of BIG pieces of steel between 10 and 100 ft (heaviest
> lift just over 10 tons - to 35 ft)


Whether it falls 2 feet or 100, it's still a disaster..