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Setting Up A Z-Drag |
While creeking, sometimes boats get lodged on rocks and held there by the force of the water. Two or even three people are often not enough to dislodge the boat. If you know how to set up a z-drag than you know how to double the strength of yourself or your creeking team. A z-drag is basically a mechanical advantage device to pull on the boat. Often times you will hear this idea/device referred to as a "block and tackle" in science/math/engineering classes. If your team members are doing everything during the rescue and you are not sure what to do maybe you should consider grabbing your rope, pulley, binear, & some straps so that things will be ready for a different plan of attack if plan A fails. The picture below provides a basic visual of how a Z-drag is set up. If the kayak requires 300 pounds of force to free it. The man pulling the rope only has to pull with 150 pounds of pressure if everything is rolling smooth and friction is not a major issue. The pressure pulling on the boat is split between the two ropes that are going to it.
3-1 System
2-1 System
Absolute minimum gear necessary: 1 prussick 1 throw rope 2 caribeaners There is no physical way of setting up a z-drag w/o this equipment. If you don't have a prusik you can do a truckers hitch with a biner but you will reduce
your ropes breaking strength because of the knot. Additionally you cannot adjust your anchor point without untensioning
everything and unhooking to reposition.
Points of Attachment in the Z-Drag (3 Point System) Anchor point 1 - The Boat (thread the rope through a binear) Anchor Point 2 - The Tree "The Achor Point" This is where you want your pulley and a prussick Anchor Point 3 - A second Prussic with a minimum of 1 caribeaner If the boater is conscious and able to make eye contact they may be able to help attach
the rope to their boat (especially boats with anchor points near the cock-pit rim). If they are not able to help,
you may have to try and do this yourself if possible.
If the Prusk is slipping: With so many small diameter ropes out there, the kleimheist can make the difference between
getting the thing out, or being really frustrated. Use barr-tacked webbing loops from which you'll tie a kleimheist.
The webbing smay have a better bite on smaller lines than accessory cord, or spectra. This link is a great step-by-step:
Step 1
Step 2
Step 3
Step 4
It seems you may be able to stop at this point (Step 3)
Step 4 may help if you are getting some slippage.
Tibloc Another alternative
2 Point System If going from the boat to the tree then to you, the puller, you should set yourself up at
a 45 degree angle in order to achieve the greatest mechanical advantage in this situation. Supposedly there is
some mechanical advantage in this situation although I am not sure how or where it is achieved. This system should probably only be considered for lower boats and boaters over obsticles
or the like.
http://www.iland.net/~jbritton/kleimheist.htm
A munter-type hitch is made by wrapping the cord around both a locking biner and the rope. Also, not too repreat
myself too much, but a kleimhiest is a great alternative (cheap, and safe) to a mechanical camming device. And,
most importantly, drape something on the line to keep it from snapping all the way back to the operators...
If you don't currently carry this stuff check out the "Drag Bag". It will set you
up with the bare essentials(a mesh bag with a prusik, 2 biners, and a pulley) and you add accordingly what you
wish.
| An alternative to the |
If you want a link to some good knots go here: www.realknots.com/knots
More Advice Provided on April 27th 2004:
Here's a couple of thoughts based on my 30+ years of ww boating.
I carry a large (I mean really large) climbing chock to use as my anchor point. The chock is slung on a piece of
1" tubular webbing. I try to set the anchor point (under a large rock) as close to directly upstream of the
pin as possible. This allows me to use less rope in the z-drag which makes it function better because you don't
have to work the bag thru the prussic and the carabineers. It also means that you are pulling the object up away
from the rock instead of across it. I've used this technique to unpin rafts which are much difficult than hard
boats. Someday I expect that I will not be able to retrieve my chock but I've been using my current one for over
25 years.
I use some small pulley wheels which fit on the carabineers. These greatly increase the efficiency of the z-drag
without carrying extra pieces of equipment. Unfortunately, I can't name a US source for these-I bought mine in
a shop in Bonn, Germany. However, I've heard a rumor that they are now available in the US.
I always cI noticed one crucial piece missing from both drawing -- a pfd, or any other suitable object draped over
the line to slow and snap backs if the line breaks. I see more and more people choosing mechanical camming devices
these days (the merist of which can be debated until the cows come home.) I think the risk for shearing the sheath
and snapping the line is probably pretty high --
Another comment made about this page:
I am not some saftey guru, but I have been hit with a 'biner that snapped back. It hit me in the chest and not
the face, and still left a hugh bruise and welt despite the pfd I was wearing.
Just a thought. It's probably good to know a few difference camming knots like the prussik, double prussik, Kleimhiest,
and the kleimheist with the biner in it. Nothings more frsutrating then watching prussiks slip on a small diameter
line.. arry at least 3 prussics and sometimes that's not quite enough.