Port a wrap placement

[Marc]

I think he means the direction of force is potentially more risky ie. pulling anchor point sideways rather than down (inline with stem)?

 

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I think that's what he means also, but it will not it will potentially reduce the load on the anchor by a small margin, and the force will always as a rule be pressed downwards in a rigging scenario.

 

Had this discussion many time with base anchors and the slightly iffy though that you ar doubling your load at the anchor point, which is not strictly true there are so many variables.

 

One example is how we often install pull lines from the ground and base tie when straight felling, base tying as we all know exerts twice the load at the top point, so should we also not get twice the pull going by by the twice the load at anchor point?

The reality is no you do not, at the base you actually get no extra torque than you would if tip tied, and the base tie exerts no real great strain at the point in the top of the tree where it is deflected down to the base tie.

 

Force vectors twist my mind, I wish I could grasp the finer details and calculations, in reality you not going to need to make those calculations but and understanding of the concepts help.

Edited December 28, 2016 by Marc

[Riggerbear]

I think he means the direction of force is potentially more risky ie. pulling anchor point sideways rather than down (inline with stem)?

 

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Like Marc has explained very well, you would think the sideways strain is a risk, but in reality it isn't within reason. Look up the physics of rope angles and how it effects loads, it's a tricky subject to get your head around

[Mick Dempsey]

worth a read

http://vtio.org.au/wp-content/uploads/2010/07/Working-the-Angles-i.pdf

 

It was posted earlier in the thread.

[Riggerbear]

Nice one Mick

[Mick Dempsey]

Nice one Chris I guess.

 

I just looked through it at length. It's really very good.

 

Lots of stuff I knew once then forgot in the fog of war.

[Mark Bolam]

I think he means the direction of force is potentially more risky ie. pulling anchor point sideways rather than down (inline with stem)?

 

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That's what he means.

He has trouble expressing himself sometimes.

 

 

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[Marc]

Like Marc has explained very well, you would think the sideways strain is a risk, but in reality it isn't within reason. Look up the physics of rope angles and how it effects loads, it's a tricky subject to get your head around

 

Well glad you understood what I was on about as re reading what I said I have no idea what I was rambling on about, which is pretty standard at this time of year whilst replying on a mobile phone and self medicating with copious amounts of alcohol at mid day.

 

I always think the base anchor and pulling trees over is a good example, often srt workers harp on about the merits of top tie over base tie when it comes to doubling the loads, it is actually a little more complex than that, the case in point is pulling trees over surely you would get twice the pull base tied over a top tie? The reality is different you gain no real leverage advantage and no extra strain v top or base tied and when implemented correctly you can reduce or more favourable load a tree by spreading- through multiple forks, anchoring on adajacent trees etc.

 

The link you post covers it well.

[chrism3513]

It was posted earlier in the thread.

 

was it?