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Yarder Cable Sizes and Tailhold Rigging

Started by Warrking, September 12, 2014, 11:36:51 AM

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Warrking

Hey guys,

I'm doing engineering work in coastal BC and am wondering wondering about tailholds.

We use the attached table for deciding when we can rig higher on a tailhold, but there's some discussion as to what cable size is most frequently used and the accuracy of the table.  Can anyone provide some insight?  Also I would never suggest rigging above 10m, but frequently 5m will give me the deflection I need.  What sort of tree dia would you use for rigging under 10m?

We generally layout for grapple yarding with a 60' tower, but occasionally high lead.  It's a shame that we rarely get to meet or receive feedback from the loggers unless we drive to a block on our own (unpaid) time.


beenthere

Warrking
From what I read in your OP, you are questioning the accuracy of the table.

Might be time to bite the bullet and do some testing on that accuracy. That or running down the history of that table data to learn how it was put together.
If actual testing was done, or if just experience was used, either likely had a margin of safety factor applied.

If there were failures, likely your firm would be hearing about them.

Nothing in the table that takes into account the growth rate of the Doug fir trees picked, and some second growth Doug fir would be my concern.

Maybe others here can offer better comments.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Warrking

Less questioning of the table itself, but more questioning how to use it.  ie what cable sizes are guys using? I assume the largest size is for the big cross valley skyline systems that nobody uses anymore, but the small one would seem like an irresponsible choice.

Also I'd just like some real operator opinions.  I rarely get to hear what the loggers have to say.

thenorthman

First my experience with yarders is limited.

however seems like the chart is spot on.

most folks seem to run 7/8 to 1-1/4 skyline/mainline all depends on their machine, a little skagit bu30 with a christy carriage would look kinda funny trying to sling 1-1/4 anything...

As far as the real little stuff like 5/8 don't discount it off hand, some of those really little yarders like the Koller I think run 1/2 to 3/4 main and like a 3/8 to 1/2 haulback.  May not be able to pull in a huge turn, but for what they do its perfect.

When it comes down to it it has more to do with the size of timber and what kind of power you can put to it than anything else.

There is an outfit on the Olympic peninsula running a Berger MK VI. If I remember correctly they have a 2" mainline, but they do run cross canyon craziness and do strange things like drag d6 cats across valleys.

Look up flying cats on youtube.
well that didn't work

BargeMonkey

 I just watched that video... thats something to watch. Wow.  :o

Warrking

Thanks, that kinda supports my thoughts.  It's hard trying to engineer blocks for a timber sale as I never know what the winning bidder owns or how they log. 

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