Rigging Workshop

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PATC Rigging Workshop, Sharpsburg, MD, September 24, 2017 — When you have to drag  big rocks or logs, or bridge a creek, how ya gonna git ‘er done? That’s what we learned this weekend at the Potomac Appalachian Trail Club rigging workshop for trail maintainers.

Rigging is mature technology.  It’s used every day in construction and factory settings. Sailors know it well.  The same principles that lift tons of concrete 25 stories in building construction or off-load container ships are the same ones trail maintainers depend upon to safely move 1,000 lb. rocks and ginormous logs, rootballs and bridge stringers.

That bridge across the creek?  Guess what?  Riggers used high school physics to calculate the “working load limits,” “sling tension,” “share of load,” “choke angles,” and many more factors required to safely drag, lift and place large objects in the right position deep in the back country where lumber sexual street cranes fear to tread.

The first four hours were spent in the dreaded classroom drinking from a fire hose pumping out basic concepts, safety rules, vocabulary, equipment familiarization, calculations, and expectations for the weekend.

Flashback to Vietnam era military training, “If you don’t learn this, you will die in Vietnam,” the sergeants would extol with the subtlety of jackhammers.

Well students listen up, a snapped steel cable or rope pretty much functions like a weed wacker except with enough power in the right circumstances to maim,  decapitate or de-limb your ignorant butt.  The consequences for carelessness or ignorance range from disability up to and including death!

After fully appreciating the weed wacker metaphor, I thought,  “Why do I want to learn this stuff?”

“So you stay in one piece,” my guardian angel’s voice intoned.

“Oh!” I replied.

I noodled for second.  My guardian angel takes responsibility almost nothing so I knew with the motivation of a lonely guy at closing time that I was on my own.

With that ugly metaphor in mind, my eyes and ears locked in on doom prevention for the remainder of the weekend.

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Another take-away from the workshop.  The price of my toys continues to escalate.  This little sucker is a grip hoi$t.  This model can move a ton although there are larger and heavier models that can handle much more.  Want to win a tug of war?  Get one of these babies!

Properly attached to the anchor and ready to go.

But there’s more to it than a grip hoist.  Ya got your pulleys, shackles, chains, ropes and the know-how to properly hook them up. Time for a second mortgage if you want to buy the toys.  Otherwise you use PATC equipment.

First practical exercise, rigging and dragging a BFR weighing an estimated 750 – 800 lbs.

Checking everything twice.

Have rock.  Will travel.

Added a pulley to change direction with the speed of molasses.  Slow and steady is good in this business.  The rock bars help keep the front end from becoming a dozer.

View from the grip hoist operator

Slow lane.

Summary day one:

A lot to learn. Most of the info delivered by fire hose spilled on the classroom floor.  I am going to practice this skill in small bites and learn to get the math benchmarked and develop valid rules of thumb.  You can lighten the load you have to carry into the backcountry if you closely calculate.  Me?  Until I learn a lot more, I’m going to over engineer everything and eat the weight.

Day two.  Highlining.

In the density of the predawn darkness I’m awakened to the purr of a golf cart somewhere between the door of our 10-bunk cabin and the awesome laminated-beam pavilion across the gravel. Our kindly hosts at the Shepherd’s Spring (Church of the Brethren) outdoor retreat center were delivering hot coffee for the second morning in a row.  You rock ladies!

I’m cocooned in an Army poncho liner (quilt) with ear phones jammed into my ears, half listening to old time radio’s “Boston Blackie” and dreaming of special times and places.

The wake up cue nudged me from dreams to reality.  You see, I normally respond to the gentle rhythms of dawn and dusk.  I wanted to stay but … the crunch of the coffee wagon on the gravel was overwhelming as a bone is to a dog.

“Add coffee, instant human.”  The pending chemical assist was an awesome incentive to get the jump on the day ahead.  My feet hit the floor in a dead sprint for the Thermos. I was not alone.  A nutritious breakfast in the dining room followed.

The words ‘high line’ connote a cable strung high in the air with a suspended load dangling below.  Fake news!  Not true.  Do that and you might die in the woods grasshopper.

Instead, a high line suspends the load no higher above the ground than necessary.  (Physics nerds and engineers know this.)  A taunt line under high tension decreases your working load limit, and that dear friends confers zero advantage.  The more U-shapped the parabola, the better.

Rigging the high line.  High means way up in a live, solid tree with a choke configuration and a pulley.  That’s the spar.  It’s anchored to another tree directly to the rear.  Hiking in the ladder has to be a joy.

Rigging a chain basket to carry the BFR.  This one’s about 500 lbs.  Like Santa, checking it twice.

Setting the grip hoist at a 90 degree angle with enough distance to pull the amount of cable necessary.

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 Inserting a dynamometer allowed us to see the actual forces at work.

Click for more on dynamometers

Ready to rock and roll.

Ready.  Steady.  Go.

BFR on the move.

Exercise over.

Please do not try this at home.  This blog is not a ‘how to’ for anything.  It is a story about our rigging workshop this weekend.  We hope it helps you understand more about what it takes to keep hiking trails in good working order and how dedicated volunteers give of their time to advance their skills.

Of note.  Many women have taken this workshop and are actively involved in PATC rigging projects.  Ladies you are welcome.  Please come.

Sisu

 

 

 

 

 

 

 

 

 

 

4 thoughts on “Rigging Workshop

  1. I would so be there if I lived closer ! Being in the outdoors playing with tools….Life don’t get any better than that. Actually listened to a little Boston Blackie and Richard Diamond myself last night !

  2. There is a lot of good physics in this workshop post. In my classroom, we did a lot of problems and labs involving situations like those. It was a favorite part of the course.

    Moving the first big rock was slow but effective. You reckon the ancients used tools like that, or just lots of people? I sawed off an 8″ mulberry that was too close to the house. It was supposed to fall in the open space between to large trees. It got hung up on one of them. My neighbor and I used a come-a-long tool to pull on it enough to dislodge it and fall the rest of the way. Your pulling tool is much heftier than our tool. You win! 🙂

    • We actually used two different come-a-long type tools. Each had several disadvantages compared to the grip hoists. They did have a weight advantage though. The grip hoist’s primarily advantage after raw torque is that it works equally well in either direction. That’s a precious safety feature.

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