Croesor - Rhosydd (25/01/26)

[Loki]

I didn’t know that fibre cored wire rope still existed but Aparrently so. Googling suggests pros and cons but one con is they are prone to corrosion and crushing.

Fibre Core vs Steel Core for Crane Wire Ropes - Bekaert

The first steel wire ropes were produced with natural fibre (sisal, hemp, jute, etc) cores and operated on cranes and winches with rope drums of sufficient diameter and width to accommodate the required length of rope on a single layer. This single layer spooling arrangement minimised the...

ropes.bekaert.com

Fibre cored wires were I believe the cause of some early cave rescues when wire electron ladders snapped.

 

[vanoord]

Probably best not to use a wire with a fibre core next time.

Fibre core wires are more flexible than full wire construction; and are intended for use going over sheave blocks, so not designed for uses such as zip wires. I'd also hazard a guess that the breaking strain would be slightly lower than a wire core.

Your comment about electron ladders is interesting: a fibre core would be better suited to being rolled up regularly, but if that results in premature failure, that's a big problem.

The risk of internal corrosion causing weakening is something worth bearing in mind if anyone encounters a fibre core wire in future, but that's not to say that a standard wire won't corrode over time.

Good to know it was 11mm or 12mm - 8mm would have been reckless.

 

[Bob Mehew]

I can't recall the detail but we used to soak electron ladders in a hydrocarbon to impregnate the fibre core to reduce water uptake and hence hinder corrosion.

 

[Fulk]

I have a distant memory of soaking hemp-cored ladders in a solution of lanolin (I think) in some solvent in order to impregnate the hemp and make it (putatively) less likely to absorb water and cause the wires to rot . . . but it made climbing them a bit messy for the next few trips.

Eeeh, the good ol' days, eh?

 

[Maj]

I have recently soaked a couple of our digging ladders in boiled linseed oil. Easy enough since just require an inch or so in the bottom of the right size bucket and soak one side of ladder at a time. Boiled linseed oil dries out quicker than non boiled.
Digger's ladders are probably the worst for corrosion due to either the duration left rigged and/or the amount of regular use. Also getting caked in mud and if not cleaning and dried out between sessions can exasperate the potential problem.

 

[RobinGriffiths]

Attach a lump of sodium as a sacrifical anode. Erm - magnesium then...

 

[Brains]

The problem with the ladders was the hemp core rotted out, causing the swage eyes to become loose and fail. There is a good section on this with X-rays in "Race against time" if you have a copy. I believe a number of incidents were caused by this failure type. As mentioned, soaking in lanolin and other compounds help prolong the life of a ladder

From page 91, showing a failed swage on a belay

 

[Stones]

The Ziplines on the high level route in CRTT have been checked and are all corroded. Please avoid the high level route.

 

[vanoord]

Attach a lump of sodium as a sacrifical anode. Erm - magnesium then...

Interesting idea, but I suspect the while thing would have to be immersed in water for it to work!

My grasp of chemistry has faded considerably over the past three decades, but my understanding of marine corrosion isn't too shabby...

 

[Cantclimbtom]

One thing that surprised me (with my weak understanding) was that for boats you can't just shove a big lump of sacrificial anode on the hull (zinc for seawater or magnesium for fresh water) and then job done.
They only protect the surrounding 2 metres at very most, so you need many anodes sited all along the hull obviously depending how long it is. You may need those blobs of sodium every 2 metres down the zip line.
Perhaps electrifying the zip line is a more sensible approach?

 

[Alex]

Makes you wonder about go-below's wires and other commercial mines using similar zip lines. However, I suspect they get regularly inspected and replaced as the corrosion here was quite obvious by the looks of it.

 

[Cantclimbtom]

Maybe they can afford £8 per metre for 12mm stainless steel wire rope 7*19 given it's a business and not the hugely generous donation of individuals

 

[Alex]

Aye it was a donation and great that they did that too, however, given this accident and the flaw with the wire it has brought up, I think if these zip lines were to be replaced then there should also have a rope alongside you can clip into with a cows tail so if that goes you still have the rope. Rope generally lasts longer provided it's not on an edge or anything. (Or is there already a rope there, I can't remember it's been ages since I had been down there).

 

[georgenorth]

Makes you wonder about go-below's wires and other commercial mines using similar zip lines. However, I suspect they get regularly inspected and replaced as the corrosion here was quite obvious by the looks of it.

Commercial operators must inspect the cables every 6 months, in order to prevent things like this happening.

 

[Alex]

Commercial operators must inspect the cables every 6 months, in order to prevent things like this happening.

good to know.

 

[cavemanmike]

Aye it was a donation and great that they did that too, however, given this accident and the flaw with the wire it has brought up, I think if these zip lines were to be replaced then there should also have a rope alongside you can clip into with a cows tail so if that goes you still have the rope. Rope generally lasts longer provided it's not on an edge or anything. (Or is there already a rope there, I can't remember it's been ages since I had been down there).

There’s always been a rope along side the wire cable

 

[vanoord]

Maybe they can afford £8 per metre for 12mm stainless steel wire rope 7*19 given it's a business and not the hugely generous donation of individuals

Galvanised is more suitable and significantly cheaper: I've not got an up to date price list from our supplier, but I'd be surprised if 12mm (7x19) was even half that.

 

[Cantclimbtom]

I was horrified by that cost, it was based on a 50m spool from https://www.gsproducts.co.uk/12mm-7x19-stainless-steel-wire-rope-50mtrs
You can do better if you shop about, but be aware stainless is especially costly at the moment

 

[Occasional Borderer]

There’s always been a rope along side the wire cable

There wasn't unless you rig your own backup. (2025)
It's single wire or the wire bridge.

 

[Chris Curry]

There wasn't unless you rig your own backup. (2025)
It's single wire or the wire bridge.

How do you control your speed then? I haven't done it for a couple of years, but there always used to be a rope alongside the zipline to clip your long cowstail to and to keep a hand on to slow you down. Otherwise you would hit the far bank at a fair speed. Hope folk haven't been resorting to running their hand on the wire...