Sunday, October 23, 2011

Make Your Knots Right - The Blake's Hitch

Tying knots correctly is the cornerstone of rigging safety.  I have found knots incorrectly illustrated on the internet - namely the Blake's hitch, the bowline and the buntline.  To my surprise, those posts aren't corrected when the owner is notified and informed about their error.  Thus it's time to take a critical look at a particular attachment knot and learn a method of tying that mitigates errors.  Here the focus will be on the Blake's hitch.  It's an essential climbing knot to know.  It also finds use in common place activities where rope tension needs to be maintained. 
My climbing career had a feeble start in 1980.  A variant of the taut line provided the friction hitch attachment.  That weak knot combined with the use of a three strand laid nylon rope, led to fixing loose coils and managing frequent slips while in the canopy.  When the Blake's hitch came out in the 90's, there was a sense of elation.  Here was a knot that was stable in the rigors of a climb and that was highly reliable in its hold.  Moreover, it was a beautiful knot.
The story doesn't end there.  The Blake's hitch can be tied wrong.  The result is a weak knot that slips more than it holds.  However, if tied around the contour of the hand, the mind does a better job of tracking the progress of the knot, which ensures its correctness.  I have caught myself tying it wrong.  How does that happen?  Whenever the knot is rotated and my eyes are distracted, a visual orientation is lost.  By using the hand as a template, the brain has a solid reference point on what's right.
To best understand the Blake's hitch illustration below, consider the various parts of the knot.  The gray line is the climbing rope.  Part #1 makes the attachment point to the climber and forms the first coil.  Part #1 and #2 are made as loose coils.  Part #3 and #4 are snugly coiled around the gray rope.  Part #5 is critical for compressing the coils together.  That compression is established by threading #5 up through the center of the coils formed by #1 and #2.  An in-line fig-8 serves as a stopper knot on the tail of #5.  
Blakes Hitch
The knot is complete when tightened and loaded by the climber.  Friction hitches like the Blake's hitch are mechanical devices that replace the grip of a human hand.  The coiled rope physically performs the function of curled fingers in a death grip.  Indeed, the orientation of this imaginary human hand is with the thumb placed in the down rope direction.  This thumbs down orientation best simulates the dynamic of the Blake's hitch.
Where part #1 forms a coil on the climbing rope, the majority of the climber's weight loads there.  A pinch is established on part #5 like the thumb pinches the first finger: although, it does it with tremendous mechanical advantage.  As designed, the climber's weight seemingly welds the lower part of the knot to the climbing rope.  The climber takes weight off and the knot can slide up with the push of a hand.  It locks again when the climber sits in the harness.  It goes down rope when the top of the knot is pulled down.
Here's how to take a good thing and mess it up - as illustrated below.  If part #5, goes on the opposite side of the climbing rope, a horrible slide results. How?  As part #1 pulls part #5 down, part #4 is pulled down.  There is no lower pinch in the knot to resist gravity.  The climbers weight is transfered to part #4 - the top of the knot.  As already indicated on normal use, the hand presses down on part #4 to start a descent.  With this knotting error, part #5 is mechanically performing a descent, and it's independent of the climber.  To arrest the descent, the climber has to get off the knot.  Please, appreciate the fact that there's not a significant visual difference between the right and wrong formation.
Dangerous Knot
Knots are traditionally taught by the flying rope method.  The end of the rope flies through space and encircles the target.  This tying approach puts quite the strain on the brain.  This strategy fails to reinforce knot memory and knotting consistency.  It takes brute force to establish a reliable skill that way.  Seasoned knotters establish quirky touch points and minimize open space paths.  The hand is the best knot template going: the brain likes it.  Here, a rope on hand strategy is applied to the Blake's hitch.
Illustrated below is a method for tying the Blake's hitch by using the contour of the hand.  It starts with part #1 laid between the thumb and first finger.  The fingers grip the climbing rope, and the first two coils (#1 & #2) are made around the thumb.  The next two coils (#3 & #4) go directly around the gray climbing rope.  Part #5  is pulled to compress the coils, and it travels around the thumb opposite to the direction of the coils.  Part #5 is then pulled up through #1 and #2.  Part #5 replaces the thumb position.  A stopper knot is placed on the end of part #5.  The Blake's hitch is complete when tightened and tested.
Blakes Hitch Tied to the Contours of the Hand
I have short video on You Tube that can reinforce this discussion.  You can search under "

Blake's Hitch Tied with Contour of the Hand" or you can copy this link as follows:

It's good to develop routines that enforce rigging consistency and quality.  Before using a knot, stop chewing gum, don't answer the cell phone, and stop talking.  Look at your knot and ask yourself, "Did I tie my knot correctly?"

1 comment:

  1. page looked promising, however the images don't load and the link is "dead".

    any help?