Anchors

I often disagree with people about how kites should be anchored. I have had disagreements with David Gomberg, Peter Lynn, and most recently, Dave Hogan. If you don't agree with me, you are in good company but I feel that it is time to properly state my case.

There are many ways to anchor a kite:

1. You can anchor it to something solid in the landscape.

   A tree. A fence post. A building. A mountain. Something pre-existing and immobile.

2. You can anchor it to something heavy.

   A bag of sand. A bag of stones. A block of concrete.

3. You can anchor it to something heavy an buried.

   A sand anchor.

4. You can anchor it to something light an buried.

   A steel or wooden plate buried in the beach.

5. You can anchor it to a stake driven into the ground.

   A single stake or multiple stakes.

6. You can anchor it to a stake screwed into the ground.
7. You can anchor it to a human or a group of humans.
8. You can anchor it to vehicle.

   A car. A Hummer. An earthmover.

9. You can anchor it to a boat.

   A barge. A speed boat. A jetski. An oil tanker.

10. You can anchor it in ice.

    Drilled through the ice or frozen into the ice.

They all work. I have used all but the last two. They are all provide sufficient resistance to fly one or more big kites.

But the issue is not whether they work. The real issue is about how they fail.

They can all fail. Every single one of them. It is our duty to consider how they will fail and to determine the consequences of that failure. So lets go through the list and consider those failures.

1. Failure of a solid anchor.

   Mostly, solid objects get in the way of kite flying but at a fundamental level a flying field is deliminated by obsctructions and often those very obstructions, be them trees, fences, buildings can offer substantial anchors.

   The first problem with these is that they might not be as solid and substantial as they appear. Recently, a well known flier pulled a substantial beam out of the foundation of a building, which proceeded to be dragged for miles across the Austrian countryside. Fence posts can have similar problems, there is a tale of an octopus-flier anchoring to post in a wire fence. The Octopus pulled the fence post clean out of the ground, but did not break the wire fence - it proceeded to pull the next post out too.

   Then there was the case of the flier who anchored to the large telegraph pole that appeared to be a permenant feature in the beach. He ripped the pole out of the ground and proceeded to drag it across town.

   So, if you are anchoring to something solid, make sure that it is indeed as solid as you believe, Because otherwise it will become the equivalent of a wrecking ball, looking for something expensive and fragile to crash into.

   But even if the solid item stays fast, the anchor can still fail. The strop can break, or the line can break. Check for wear on sharp edges.

   So, what happens then? Several things can go wrong.

   If the line is elastic (Polyester, Nylon, Polypropylene), then a huge amount of energy will be released and the line will accellerate, often with a huge bang as the loose ends break the sound barrier. They are capable of causing serious injury on their own and even worse of laced with chunks of metal such as carabiners or belay devices.

   If the line has a reasonably low total mass and is flying a single, soft kite, then the kite will likely collapse, quite safely. The biggest danger here is that the kite or line land on a road. Many drivers are too stupid, impatient or unobservant to spot a falling line and stop and wait for it line to be cleared. A line caught on a fast-moving vehicle has the potential to cause serious injury or damage very quickly.

   If the line has a large pilot or a fairly efficient display kite (such as a Manta Ray), and there is other stuff on the line (windsocks or other kites, then there is a strong likelyhood that the kite(s) at the top of the stack will keep flying whilst the lower stuff drags until it catches on something to make an impromptu anchor. Given that we only got in the situation because the pull was so strong as to cause an anchor failure in the first case, there is a good chance that we also damage whatever we caught on. A favorite target is power lines.

2. Failure of a heavy anchor.

   A bag of sand, a bag of stones or a block of concrete make a particularly good anchor because the have a particularly safe failure mode. If the wind comes up enough to move the weight, it will only move it a little. The movement of the weight reduces the apparent wind to the kite. The entire weight of the bag is still available to resist the kite, the increment in pull that caused it to move is small in comparision. The anchor moves slowly (so you can run after it and catch it!) and all you need to do to stop it is to defeat the incremental pull that caused to to move. Typically, all this requires is someone to stand or sit on the weight, whilst other folk deal with the kites.

   Watch out for failure of the anchor it'sself. A bag splitting and dumping it's load, or the handle(s) breaking.

3. Failure of a heavy anchor that is buried.

   Whilst a heavy anchor has a safe failure mode, paraxoxically, a heavy anchor that is buried has a very dangerous failure mode (despite being recommended by certain folk who really should know better...)

   If you take a heavy weight and bury it, it is very efficient at resisting the pull of the kite. Not only to you have the weight to resist movement, but the initial movement of that weight must be upwards.

   So what is the problem? The question is not about whether or not the anchor will hold the kite but rather, it is about how it will fail. Because as sure as eggs are eggs, every now and again, the wind will come up and the anchor will fail. When the kite pulls too hard, it pulls the weight up, out of the sand. Now things go badly wrong, because released from the hole, the kite is easily able to drag the heavy weight over the field. Typically, it will be dragged much faster than anyone can run. It won't stop until it hits something solid. So, we have a heavy weight careering across the field faster than anyone can run, yet providing sufficient resistance to the kite to keep everything inflated and flying properly. What happens when it his something solid? Ah yes, this didn't start until we had reached the point at which the kite had sufficient power to lift the anchor straight up. We have probably lost some weight on the way across the field, so whe the anchor is stopped, the kite powers up until it has enough pull to lift the anchor straight up and over the obstruction.

   It is hard to think of a more dangerous way to anchor a kite...

4. Failure of something light and buried.

   Dig a hole, and bury a "dead man". A plank of wood or a sheet of steel and fill in with sand or soil on top. This can fail in several ways. Damage to the line or failure of the anchor can lead to sudden release much like the similar failures associated with solid anchors above. If you do pull the anchor out of the ground, it is likely to act like a missile initially, but since it has little weight, it is unlikely to keep the kite inflated and get dragged too far.

5. A stake driven into the ground.

   These are notorious for failure. They get pulled free on a regular basis, whereupon they typically shoot through the air, looking for a human to impale. I have pulled a pair of 1m spikes out of the ground with a single Manta ray on a short line, due to strong wind and sandy soil beneath the grass. I have had the spikes fail due to metal fatigue on two occasions. They are also prone to problems with wind-shift and looseness due to vibration. You can drive a spike into the ground with a slegehammer in the morning, only to find that it pulls out easily after a day's flying. If the wind shifts by 180 degrees during the day, even a small kite could remove the anchor for you.

   Spikes also have the problem that they cause difficulty even when they are working properly. They cause thousands of pounds worth of damage to kites that catch on them and they just perfect for tripping over.

6. A stake screwed into the ground.

   These seem to be particularly popular with Germans for some reason. They are surprisingly effective but they still fail occasionaly, in much the same way as a metal spike - an airbourne missile.

7. A group of humans.

   Sometimes a group of people can be an effective anchor. A small group has a substantial mass, and they can manoever in any direction through other people without the danger inherent in manoevering a vehicle through a crowd.

   But they can catch you out in surprising ways. They tend to run out of control. When an untrained team is told to "pull", they will be inclined to run together as fast as they can, without regard to what the kite is doing - often, only small movements are required. If a team is used to move a line to diffeerent fixed anchor, it is difficult to get the team to release the line sumultaneously. It is very easy for one person to be left holding on and become airbourne as the anchor takes the strain.

   If a kite overpowers a team, the results can be unpredictable. Experienced fliers may hold on, because they are used to dealing with being overpowered, whilst inexperienced members may let go, immediately agravating the situation for the others. Also watch out for the new guy at the end of the line that ties a loop round himself...

8. A vehicle.

   Vehicles can be excellent anchors. They have substantial mass and are mobile, so that they can be manoevered by fliers as conditions change. Any vehicle used should remain unlocked, with the keys in the ignition, so that it can be moved quickly by anyone when necessary.

   Think about the mechanics of the vehicle when deciding where to attch the line. In a front engine, rear-drive pickup with the handbrake on and the engine in gear, the tow-ball on the back may seem attractive, but remember that only the rear wheels are braked all the weight is at the front. The front is often a better choice. It also makes it easier to see what you are doing when manoevering the vehicle.

   Earth moving equipment is excellent but has the drawback that usualy it requires a specilist driver who is never available when you need him.

   It is worth noting a couple of surprising failures, both involving vehicles.

   In Kuwait, we had a side-line anchored to a hook on the front of a truck. The hook should have been strong enough to pick up the truck and dangle it but the casting contained a large bubble and it broke off at a relatively light loading. The line was made of Spectra, so there was little energy released, but it still caused Kathleen a wrist injury.

   In Fano, some kites were being flown anchored to two little trucks, tied nose-to-tail. The line between the trucks failed due to chaffing and the remaining truck leapt a couple of meters. The person sitting on the tailgate had a very lucky escape

9. Boats

   I have little experience in this area. But the usual principle applies. Work out what will fail first and what will happen as a consequence.

10. Ice

    I have no experience in this area. I shudder to think what the failure modes might be...

And finaly, next to most anchors is a spool, heap or bag of unused line. Keep it net and tidy, so that people don't stand on it. If something fails, the last thing you want is a bystander going off in the direction of the kite, feet-first.

Andrew