The Magnet Anchor

I’m an advocate of creative approaches to ropes and rigging — both in training and in the field. These are the spaces that turn gears and illuminate light bulbs. These are the spaces where we evolve as vertical practitioners.

This little experimagnetment all started with the simple pull of a magnet fixed to a refrigerator. The magnet popped off in my hand. “That must be around 5lbs of force,” I thought.  I just wrapped up a section on load sharing anchors while leading a climb training for Greenpeace USA in the Summer of 2014 and curiosity got the best of me.  Could I build an anchor out of these simple magnets?  How many would it take?  And so it began.

I weigh around 160lbs. Divide that by 5lbs (my estimate of how much force it took to pull the magnet off the fridge) and I was left with 32 — the minimum number of magnets needed to hold my weight.  This is assuming that my estimate was accurate, that I would be able to equalize all the magnets ‘perfectly’ and that additional forces don’t exist when getting onto or suspended from an anchor.  Knowing better I decided to double the amount but after searching the warehouse for every magnet available I was left with 51 magnets so 51 magnets it was.

My friend and fellow rope nerd, Van and I quickly got to work tying loops made from random bits of 2-4mm accessory cord to the plastic knobs on each magnet. These would become the individual anchor points for each of the 51 magnets.

magnetanchor-close

photo by Basil Tsimoyianis

We divided these into clusters that we painstakingly equalized into seven load sharing anchors.  These seven anchors were then brought together and equalized to create a single master point.

photo by Basil Tsimoyianis

photo by Basil Tsimoyianis

The end result was one master point made from eight equalized anchors whose loads were shared across 51 individual anchor points – in this case magnets.

photo by Basil Tsimoyianis

Untethered magnets will fall if they fail so if using this for training purposes don’t make the same mistakes pictured here – wear a helmet, have a separate belay line, and place a crash pad underneath you. Photo by Basil Tsimoyianis

The anchor was weight tested by people of varying sizes/weights and some even chose to bounce test it. Minimum breaking strength was never determined but I think it’s wise to call this one body weight only.

I’ll be the first to admit that this magnet anchor is not the most practical when it comes to field use but it’s an excellent training tool that highlights the concept of load sharing anchors and importance of equalization.

WARNING:  Magnets are not reliable anchors. Using a magnet or magnets as life support can and will likely kill you.  Untethered magnets will fall if they fail so if using this for training purposes don’t make the same mistakes pictured here – wear a helmet, have a separate belay line, and place a crash pad underneath you. Heck, grab yourself an umbrella while you’re at it.  Have fun but be careful.

Tug-O-Angle

Angles and vector forces are an intimate part of rigging and it’s easy to get lost in the numbers.  Heck, it can even get frustrating!  Use this simple exercise to cut out the math and get a feel for how vector forces and angles play into rigging.  The math, numbers, and vector charts can come after.

Tug-O-Angle draws on experiential learning and is a fun way to kick-off an anchor workshop as it puts a variety of concepts into perspective and provides participants with an opportunity to feel and experience forces directly.  This exercise requires a minimum of 3 people but the more the merrier.

SET-UP

There are multiple ways to set-up this exercise.  My preference is to have two separate lengths of rope.  Find the middle point of one of these lines and tie an eight on a bite — these are the legs for your anchor.  Tie an eight on a bite at the end of your other single line — this is your load line.  Attach your load line to your anchor line using a carabiner.  See below.

tug-o-angle_simplebw

Assign an equal amount of participants to each leg of rope.  This may not look fair but that’s the fun part.  Start with the legs of the anchor at a 45° angle with the load line positioned for a straight pull.  Make sure that each leg of rope and it’s assigned participants run straight in the intended direction.

The job of those on the anchor side (left in the image above) is to be a solid and strong anchor.  Direct them to hold fast and strong with legs shoulder width apart and one leg in front of the other — they must only hold and not pull!  Check in with your anchor teams and make sure they’re ready and “bomb proof” before moving onto the load team.

The job of those on load side (right in the image above) is to apply their load to the anchor.  Direct them to start with a static pull — if the anchor side holds strong direct them to apply some dynamic pulls or shock loads.

Observe what happens and debrief with participants on both the anchor and load side.  How did it feel?  What did they notice?

Repeat the exercise increasing the angle of the anchor side to 90° then 120° and finally 180°.  What do you observe each time?

tug-o-angle_exercise

Pull from the group and debrief the overall exercise.  What conclusions can be made?

Have fun with this exercise.  Add a change of direction, throw in some pulleys, change up your anchor, etc.  Find something cool?  Let us know what you discover.

Contributed by Basil Tsimoyianis