UKC

Hey, so I was hoping I could pick some brains for a zipwire idea I'm trying to suss out. So zip wire over a lake, the low point on the land at the other end of the lake (maybe even a running stop) and an automatic or easy release system so the person going down it can release into the water but only after a curtain point. Any idea's?

In reply to Mesoraven:

Automatic : ( maybe not...... We used to use a grigri off the pulley rope, tied off with a hitch, then abseil to ground.

In reply to Mesoraven:
This was done on a tv show not too long ago. Might have been called the indestructibles, or something a bit like that. It was hosted by Tim warwood.

Anyhows, they used a kite surfing quick release system-mega strong, but can be released instantly under full load.

In reply to Mesoraven:

Is it for yourself/fun or paying customers? If the latter then there's quite a few difficulties and and most zips have someone at the end to take the person off. If you want them to get themselves down then as andy said something like a grigri or preferably something with a panic lock would work but you're relying on the customers being competent/sensible enough not to ram themselves into the water too fast or in the rush of adrenaline forget all their training and for example hold the rope above the device instead of below before opening the lever and burn themselves.

As far as I know there's no device that does it automatically but if you find one then it would be of interest. The difficulty is making a device that lowers people at a consistent speed for varying weights, varying rope widths, when the rope is wet and dry and when the rope is new and shiny and older and a little fuzzy. That's a lot of different conditions for an automatic device to cope with. A fat man on a shiny new rope is very different from a small child on an older, wet and fuzzy rope.

In terms of having them stop in the right place you'd need stops on the zip line, again different weights of people will naturally settle in different places on the zip line unless you have stops to hold them in position.

I imagine there's a lot of major issues with crossing a lake re. planning, waterways access etc. but it sounds like a cool idea. I'm not sure the idea of people splashing around in the water trying to undo carabiners is ideal.

Just rereading your post maybe you mean just like a drop from the zip into open water? If it's paying customers you might struggle to find something suitable. There's lots of quick release buckles and such like but I wonder whether you'd find any that were suitably rated for climbing loads and I guess getting the depth and height right would be quite difficult. The shallower the water the greater liklihood of someone heavy hitting the bottom and the deeper it is the greater the liklihood people will need to be rescued i.e. rescue boats on the water. The shock of falling into cold water from a height could be difficult for people to deal with and sounds relatively dangerous to me.

In reply to Mesoraven:

The way it used to be done was called 'letting go' but that was when you hung on to a bar that was attached to the pulley.

In reply to Sharp:

There are plenty of options for a quick release that will hold sufficient load and release under that load. The problems you have are making sure it can't release prematurely (mechanical or electronic interlock) and doing so in a very robust way (since it's presumably safety critical) then ensuring the safety of people dropped from height into cold water clothed and in a body harness.

The simplest way to trigger the interlock would be to have a fixed length string from launch-point to the pulley assembly that pulls a pin but you'd need to ensure it couldn't tangle thereby triggering early or foul the rider and garrote them. In the simplest form it's not re-settable so the rider could then potentially release into the shallow water before the landing area.

Sounds like a bad idea to me unless it's just you and your mates messing about in which case I don't see the need for the automatics.
jk

Thanks for all the reply's and some great in for there. So more information. It would be for paying customers at an activity centre its just an idea we are toying around with to see if its even possible to do before trying to figure out risk assessments and stuff. So we have a current zip wire over land set up is a gri gri attached with a Minter's mule redirected to the trolley to allow us to lower. With a safety line. So. I get that weight and wire difference and wind and the rest will change speed and timing and so on. Which is why I was looking for any sort of auto release (the windsurfing one is a good idea thanks. I'm thinking something that release from the harness then the participants just have to cross their arms on their body. And as for the water side we run watersports as well so it would be quite easy for us to have a lvl 1/2 coach in a canoe ready to rescue/ tow the participant to the lake side and the lake is more than deep enough the mojaroty of the way across. But keep going guys anymore idea's comments please their all really helpful.

In reply to Mesoraven:

So. Sounds SO exciting! So also sounds like you don't know how to make it work? So you want to allow the paying customer to self release to drop off a zip-wire into water? And, so, also NOT release over dry land to become a stain on the landscape.

So I would think long and hard about why you would want to do that beyond the money it might bring in. So I would also ensure ongoing discussion with your insurers.

So, employing someone to proof-read any publicity materials you might produce might, so, improve your image.

So negative..........

In reply to Mesoraven:

A knife.

In reply to Mesoraven:

this sounds like an incredibly dangerous idea when it comes to letting jo public release themselves.

If anything it would need to be electronic so the letting go system didn't work until the required moment. maybe running past a sensor or something?

Or maybe some sort of altimeter triggered device like on a parachute?

In reply to Mesoraven:

I would point you at Alton Towers and the recent accident. If a company with tens of millions of pounds invested in construction and design can have an accident what do you think your chances are of doing it 100% safely?
I dont knkw of many engineers that would sign off your idea, i remember a few years ago an outfit was running rope ziplines in Burbage rigged only by an SPA who was ex fire service claiming this classed him as competent.
This type of rigging is out of the sphere of climbers and climbing qualifications and comes under the remit of rigging and lifting egineering.

In reply to Mesoraven:
I'm struggling a little to understand what you're describing and scanning the replies, I guess I'm not alone in that.

It's easy enough to conceive of a design trolley on a wire that could be made to reliably drop its load at a predetermined point or even one that arms and dis-arms at pre-determined points along its descent allowing the rider to trigger the drop within that window (or not) but you're always left with the question 'what if'. What if the release pin doesn't pull cleanly, can you guarantee it fails safe. What if it arms properly but the dis-arm trigger fails? What if two signals occur simultaneously, will the action be and remain safe no matter what? What if something tangles? Some of this if not all of it can be dealt with through rigorous design and testing but even if you get that right that leaves you with something safe on day one. What about 3 years down the line when there's some rust in the grease and the parts have grooves wearing in, you've got a new seasonal worker trained by Chinese-whispers doing the hook up, the mechanism is a bit sticky but there's still 30 people to ride before lunch and the boss is already on his case about something else? What if there's a submerged branch in the water? How will you justify your design, operating procedures, training and maintenance regime to the person signing it off for your insurance certificate or worse, to an inquest? All in all it sounds like a lot of risk, cost and hassle for very little extra excitement.
jk

In reply to Mesoraven:

Sounds like fun! Also a good thought exercise.

Did a simular thing a couple of years back, but we just used a bit of rope down from the pully and an italian hitch at waste level. Let go and splash. This was just a bunch of us messing around on a zip line (commercial, I am sure we would have got fired if they knew).

As for how to do it automagically no idea sorry, but good luck.

In reply to Mesoraven:
Possibly if you had some kind of electro-magnet which kept the person attached to the zip wire, and one of the staff pressed a button to remotely trigger it releasing the person sliding down, that could be a safe way of getting it to happen - if any water they were gong to descend into was free of underwater hazards all the way along the path of the zip wire, and if there wasn't any danger presented by the magnet failing to operate at the right time or at all, too?

If it's for work then an all expenses paid research trip to here:

https://www.google.co.uk/maps/place/Geneva,+Switzerland/@46.3681122,6.65426...

is in order.
If you look carefully you can just make out the two zip wires in each direction across the lake.

15 years ago you rented a "T-bar" which was essentially a zip-wire-pulley with handles. No harness, no safety, just a cargo net to stop you falling to the ground between the platform and the edge of the lake. Then they had a nasty accident. Now you get a harness and a Petzl Trac. It's not as much fun as it was but it's still well worth a day out:

https://www.facebook.com/photo.php?fbid=10151538583791481&set=t.6337564...

I don't see how you could write an acceptable Risk Assessment for a system which releases the victim over the water. You never could, it's just that today it matters.

In reply to Mesoraven:

There is a requirement in the EN standard for ropes courses and generally within health and safety law that this type of equipment is subject to an independent design assessment by a competent engineer before it is put into use with the public. You would be best to get in contact with someone at the European Ropes Course Association (ERCA) and ADIPS for some specific advice on what is likely to be approved.