Three different double-whip rigging configurations.

fhudo

fhudo

Location
Chapel Hill
Keen to gather thoughts on the difference between three different double-whip rigging setups (when used for negative blocking). Or put in another way - "keeping friction up in the tree when negative rigging". All three setups assume a bollard of some sort being used at the base of the standing stem.

SETUP A:
XRings (or safe-bloc) is attached to the standing stem of the tree with an impact block attached to the portion being cut and lowered.

SETUP B: (Reverse of the above). Impact block is used on the standing stem of the tree with XRings (or safe-bloc) attached to the portion being cut and lowered.

SETUP C: XRings (or safe-bloc) used for both standing stem portion and portion being cut and lowered.

I assume Setup C is "the best" as most friction resides aloft and also that friction and therefore load is dissipated equally through the equipment?

What are your thoughts on differences in behavior between Setup A and Setup B?
 
Mark Chisholm said:
It depends as far as I'm concerned. If there's too much friction when the piece moves away horizontally, then the stem will deflect and you will have more of a ride. In some situations I might prefer a block up top and rings on the piece. This way you get free movement, yet the piece can't destroy the block.
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That’s makes a lot of sense; I had not thought about the bending moment.

Thank you!
 
For me any of the options should work about equally well.

Something to consider is that both the safebloc and impact block are fairly large, and depending on how closely you set them to your cuts, you might not have enough space for them both without slamming them into each other as the rigged piece comes free
 
Mark Chisholm said:
It depends as far as I'm concerned. If there's too much friction when the piece moves away horizontally, then the stem will deflect and you will have more of a ride. In some situations I might prefer a block up top and rings on the piece. This way you get free movement, yet the piece can't destroy the block.
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My sentiments exactly.

Way too many people these days are combining aerial friction devices with lowering devices when they shouldn't be and just slamming the shit out of themselves, their gear and The Tree!

Know Your Friction!
 
chris_girard said:
My sentiments exactly.

Way too many people these days are combining aerial friction devices with lowering devices when they shouldn't be and just slamming the shit out of themselves, their gear and The Tree!

Know Your Friction!
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Wait I'm confused, wasn't Mark speaking of something quite different? He didn't mention lowering devices, he was strictly referring to final-anchor friction (and the idea of using block instead of Safebloc/rings, for purpose of letting the piece "freely get into its run" instead of being jammed-up immediately, if I'm getting you Mark?)

Though I do agree w/ your sentiment that there's danger in too-much friction, I'd wager it's a net benefit/positive since, at its core, it's just "built in brakes" to help our bullrope control downward forces....of course too-much can mess things up, but this is the case with natural crotch rigging (a famous, tragic example of that comes to mind, RIP Donzelli) Will say that rings make it easier to build systems that are, in some senses, "too strong" though (whether in terms of friction force applied to the line's movement, or in net terms IE overloading a union or the entire tree)

+1 to Merle's request, I see Schultz as a trailblazer of this type of rigging (and suspect this type will become the dominant type for close-quarters 'urban rigging' of heavy dismantles), he utilizes "all the new gear" better than anyone I've ever seen.....perhaps relevant to our discussion, his "The Fails" clip, since so much of the stuff in here would've been avoided if the piece had taken a quick initial run...yet Schultz almost seems to prefer snubbing-off his pieces then lowering them in many cases, would really like to hear from him hell I've been meaning to get a mini Porty so I can try some of the "tighter/quicker control" setups he does!


Would absolutely love hearing @pfannerman's thoughts on aerial friction and quick-catching pieces (or quick-slowing at least)
 
Indeed.

Do we encourage low friction departure from the hinge (by using the impact block) and yet gain benefit by putting friction high in the stem (safebloc on the double whip) to decelerate and share the load. The benefit being that we reduce the hypothetical 2 * force that could be generated in a frictionless system.

In short - does my proposed setup B get us the best of both worlds?

Lawrence please chime in :-)

QUOTE="eyehearttrees, post: 664162, member: 17318"]
Wait I'm confused, wasn't Mark speaking of something quite different? He didn't mention lowering devices, he was strictly referring to final-anchor friction (and the idea of using block instead of Safebloc/rings, for purpose of letting the piece "freely get into its run" instead of being jammed-up immediately, if I'm getting you Mark?)

Though I do agree w/ your sentiment that there's danger in too-much friction, I'd wager it's a net benefit/positive since, at its core, it's just "built in brakes" to help our bullrope control downward forces....of course too-much can mess things up, but this is the case with natural crotch rigging (a famous, tragic example of that comes to mind, RIP Donzelli) Will say that rings make it easier to build systems that are, in some senses, "too strong" though (whether in terms of friction force applied to the line's movement, or in net terms IE overloading a union or the entire tree)

+1 to Merle's request, I see Schultz as a trailblazer of this type of rigging (and suspect this type will become the dominant type for close-quarters 'urban rigging' of heavy dismantles), he utilizes "all the new gear" better than anyone I've ever seen.....perhaps relevant to our discussion, his "The Fails" clip, since so much of the stuff in here would've been avoided if the piece had taken a quick initial run...yet Schultz almost seems to prefer snubbing-off his pieces then lowering them in many cases, would really like to hear from him hell I've been meaning to get a mini Porty so I can try some of the "tighter/quicker control" setups he does!


Would absolutely love hearing @pfannerman's thoughts on aerial friction and quick-catching pieces (or quick-slowing at least)
[/QUOTE]
 
eyehearttrees said:
freely get into its run" instead of being jammed-up immediately, if I'm getting you Mark?)
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Yes thats pretty much what I was getting at. I'm all for using all of the different devices (actually running a prototype from Jamie and Morgan as we speak). Just be sure to consider when and where they make sense and when they don't.
 
Mark Chisholm said:
Yes thats pretty much what I was getting at. I'm all for using all of the different devices (actually running a prototype from Jamie and Morgan as we speak). Just be sure to consider when and where they make sense and when they don't.
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Very intrigued by the device, when will it make public appearance? There's sooo many un-tapped avenues for more useful, solid-state rigging hardware (2-hole and 4-hole safeblocs, modified figure-8 type pieces to create anchors that can mid-line attach, really there's just so many ways am surprised there's not more innovation I mean the rings/safebloc launched the better part of a decade ago and there's been hardly any development since)

Dave Driver has a good article "Where should friction be in our rigging systems?" on the subject. Having friction "inherent in the system" is (obviously) of incredible value, seems to me that, besides a piece swinging into the sawyer because it hardly moved, the only concern would be over-doing the friction at some spot in the system and over-fatigue some section of rope......This line of thinking has had me pondering a lot lately about "Wouldn't it be smarter to add redirects, even when not structurally useful, solely to get the extra rope-in-system *and* the extra friction?"
I was told at one point "You can't double-whip with rings because of the short rope lengths" (and believed it for a bit), then saw a video where D.Driver is double-whipping large chunks utilizing Safeblocs at both the terminal position *and* on the log itself!

Mark I would love to know whether the following idea presents any obvious worries to you: If rigging solo, people tend to setup their rigging near them in the canopy.....if/when in such scenarios, wouldn't it be smarter to *still* rig a basal anchor and simply have the tail of the bullrope go from there back up to the climber in the canopy(instead of to a groundsman as per usual)? I've been unable to find faults with the idea, I keep thinking I'd have so much more rope-in-system, and be able to fine-tune friction better, but hesitant since I've never seen anyone doing it...
 
Set up b is best imho for serious situation with most care required maybe very close proximity targets of value ..if rigging a spar impact block protects rig line from pinch better than rings or safbloc in near vertical spars. Worst case severing , or unacceptable amount of abrasion to rig line. The friction being mitigated in many cases negative rigging is mitigated through good rope work SKILLS. its ok to heat up a bollard or porty at base as opposed focusing on more friction aloft if its not necessary so long as tree can tolerate the force up top any of your setup above mentioned is workable in the right hands. If you have to snub off the load. The friction thing being up in the tree is good but taking a reasonable piece is more important based on the whys.. sure you can double block negativerig big ass wood , but can the tree tolerate the dynamics in the end I hope so either way....if were talking straight double whip negative rigging logs on them selves, I think its over rated and time consuming for negleable results in the end..just grab a more capable rigging line maybe with some good energy absorbtion if no run room available, if your all clear LET IT RUN.
 
The fun part about rigging for me is being able to "create". I don't think there is a single way we should operate all of the time. Whenever I am questioning my concept for a given scenario to the point of "should I or shouldn't I", I tend to pull back and go with the most time tested techniques I know. Techniques don't withstand the test of time without merit.

If you've ever heard me speak about rigging, been to a workshop I've taught, or read an article I've written on the subject you will know that I like options. I don't like using the same way for every situation and I absolutely feel that had I not created new ways to address some jobs, I would've been forced to take on more risk and the consequences could've been severe.
 
Treetopflyer said:
Set up b is best imho for serious situation with most care required maybe very close proximity targets of value ..if rigging a spar impact block protects rig line from pinch better than rings or safbloc in near vertical spars. Worst case severing , or unacceptable amount of abrasion to rig line. The friction being mitigated in many cases negative rigging is mitigated through good rope work SKILLS. its ok to heat up a bollard or porty at base as opposed focusing on more friction aloft if its not necessary so long as tree can tolerate the force up top any of your setup above mentioned is workable in the right hands. If you have to snub off the load. The friction thing being up in the tree is good but taking a reasonable piece is more important based on the whys.. sure you can double block negativerig big ass wood , but can the tree tolerate the dynamics in the end I hope so either way....if were talking straight double whip negative rigging logs on them selves, I think its over rated and time consuming for negleable results in the end..just grab a more capable rigging line maybe with some good energy absorbtion if no run room available, if your all clear LET IT RUN.
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one of the reasons you would spend the time setting up double block rigging is because used properly it does dissipate forces on the stem so well.

I am with Mark and many others here. Using a block on the tree is the right way to go. Anything other than a block will not allow the rope to “Back-feed” into the system and lesson slack. Also as was clearly stated in many posts already, be wary of the lateral forces that can be generated. Even with 2 blocks in the system the friction is greatly increased, so lessoning friction on the ground is necessary. On loads of less than 500lb it may be very different to manage all the friction if too much is applied at the rigging points. Too much friction and the load cannot be let “run” and hardware damage, chance of line pinch and stem forces all increase.

As for what to put on the piece a ring or friction device will help, reduce clutter and not become annoying due to not being mid-line attachable/ detachable. However, rope pinch is a real concern. As for hardware collision in the air, we have found it to be negligible in a proper set up. Yes, occasionally it happens, but is minor and nothing compared to the impact the hardware can take in other parts of the set up.

One of the most important considerations is where the rigging line is anchored in relation to the rigg point on the stem. It is described in an article by Gareth Tudor-Jones along with a lot of other good stuff!


Tony
 
Tony said:
one of the reasons you would spend the time setting up double block rigging is because used properly it does dissipate forces on the stem so well.
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Thats a great point tony and when the tree requires it I love utilizing it dont get me wrong. Mostly found it more reasonable when taking thinner diameter trunk wood or decayed wood, certain species that are more brittle, stuff that really moves when you free the load that maybe isn't strong as comparatively to a thicker more stout stem.
 
I prefer option B as well and option D (not mentioned here- block on both piece and spar) if the pieces are not exceptionally large. 90% of the time I’ll also have 2-3 x rings along the trunk (fishing pole) to dissipate the load and add a little bit of friction.

More often than not I find DWT is most useful when the rope is anchored away from the spar, giving a directional advantage to the lower. These kinds of lowers rarely result in a piece whacking violently against the trunk and so I don’t mind using a block for that.

I echo Mark, who btw should run for office as far as I’m concerned. Keep your options open depending on how you read the situation.
 
Stumpsprouts said:
I prefer option B as well and option D (not mentioned here- block on both piece and spar) if the pieces are not exceptionally large. 90% of the time I’ll also have 2-3 x rings along the trunk (fishing pole) to dissipate the load and add a little bit of friction.

More often than not I find DWT is most useful when the rope is anchored away from the spar, giving a directional advantage to the lower. These kinds of lowers rarely result in a piece whacking violently against the trunk and so I don’t mind using a block for that.

I echo Mark, who btw should run for office as far as I’m concerned. Keep your options open depending on how you read the situation.
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Two blocks is my preferred way. I feel it gives the most control in lowering. I don’t like rings as rigging points.

Tony
 
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