Rigging a Fixed Scaffold bar

[Bob Mehew]

This question did raise in my mind how one might quantify the difference between knots.  Work by Lyon Ltd indicates most knots have a similar level of reducing the strength of a rope, so the next step would be to look at the ease of tying and untying it after loading.  Any ideas on quantifying the difficulty of untying a loaded knot?

 

[pwhole]

Measuring the swollen lump on the right thumb knuckle two days later is my usual method

I must say I'm now almost fired up for trying that re-threaded Figure 9 again

 

[Mike Hopley]

Any ideas on quantifying the difficulty of untying a loaded knot?

I suggest measuring it in swear words per minute per fresher.

...Is that a laden or unladen fresher?

 

[Tseralo]

This question did raise in my mind how one might quantify the difference between knots.  Work by Lyon Ltd indicates most knots have a similar level of reducing the strength of a rope, so the next step would be to look at the ease of tying and untying it after loading.  Any ideas on quantifying the difficulty of untying a loaded knot?

How many times I have to hit it on the floor?


Sent from my iPhone using Tapatalk

 

[Mike Hopley]

Okay, serious answer:

Time taken for the same person to untie the knot. Repeat across different knots, and different rope diameters, and multiple people. Average results from all different people to get time for a given knot, at a given diameter.

Probably standardise the knot tightening, say 100kg, slow pull, for 5 minutes. You'd also need to decide whether any "tools" are allowed, like carabiner noses or spanners.

To get any meaningful results, you would need a lot of data. I expect you'd find that thin ropes drastically exaggerate the differences between knots.

In 8.5 mm or lower, I've stopped using figure-8 loops at single-bolt rebelays, as they are a bastard to untie. Bowline-on-the bight is a lot easier. Alpine Butterfly is easy, and Fusion is easy.

Maybe the sneaky way to get your data would be to turn it into a new competition at Hidden Earth!

 

[Fulk]

In 8.5 mm or lower, I've stopped using figure-8 loops at single-bolt rebelays, as they are a bastard to untie. Bowline-on-the bight is a lot easier.

Agreed, Mike ? except I'd say ?9 mm; in fact I had to use the marlin spike on a figure-of-8 knot in 10.5-mm rope last Sunday after a little trip down Death's Head Hole.

 

[Mike Hopley]

Agreed, Mike ? except I'd say ?9 mm; in fact I had to use the marlin spike on a figure-of-8 knot in 10.5-mm rope last Sunday after a little trip down Death's Head Hole.

Actually yes, now that I've gotten comfortable with them I'd rather just use BOTB for all my single-hang needs, even in thick rope. I like making life easy.

 

[Fishes]

I have mainly caved in Derbyshire so ropes need washing pretty much every time. I found that if I left the knots in the rope where possible that they were then so loose after coming out of the washing machine that the pretty much fell apart when inspecting and repacking the rope.

 

[Fulk]

Oh! That's interesting, Fishes, I've always untied knots before washing ropes ? I've never put a rope in the washing machine with knots in it.

 

[PeteHall]

...after coming out of the washing machine...

I've never put a rope in the washing machine with knots in it.

I've never put a rope in the washing machine, ever! The risk of domestic fallout surely outweighs any time saved 

 

[Fulk]

I've never put a rope in the washing machine, ever! The risk of domestic fallout surely outweighs any time saved 

You should have married a caver.  :tease: (In fact, in my experience ropes come out cleaner from a washing machine than they do from a conventional 'rope-washer'.)

 

[Fishes]

I've never put a rope in the washing machine, ever! The risk of domestic fallout surely outweighs any time saved 
[/quote]

You need to get your priorities sorted My partner also puts caving gear through the washing machine.

I had to stop her putting carabiners etc in the dishwasher too. They come out nice and shiny but hot sodium polyphosphate solutions aren't great for aluminium alloys.