rope/friction cord diameters

[john dawson]

Riddle me this..................

 

the general rule is rope and friction cords have to be different diameters to grip and work efectivly.

 

ie 13mm rope/10mm cord

11mm rope/8mm cord

 

so why does the 13mmrope/13mmsplit tail combo work? and why not a 13mm rope/13mm cord?

 

how about a 11mm rope/10mm cord? as mine works!

 

iv even used a 11mm rope/13mmsplit tail that works wivout any slippage.

so would a 11mmrope/11mm split tail be fine?

 

by the way, i am a skinny lightweigth chap, and the above combos are tied wiv a blakes hitch or a vt.

 

any ideas?

[Rupe]

There isn't a general rule that rope and cord have to be different diameters to grip and work efectivly!

 

It depends on the knot and the application. Split tails are larger diameter (and often equal to rope diameter) because they are used (primarily) for blakes and open prussik hitches and these hitches work well with similar diameters as long as its in a Ddrt system.

 

In rock climbing, prussik loops are used for self rescue on single ropes, in this instance a significant differnece in diameters is required because full body weight is appplied onto the loop which is not the case in our Ddrt systems.

 

The with Vt's and other fancy hitches a difference in diameter is required but there are no hard and fast rules for this, it depends on so many variables.

[RobRainford]

i did climb on a 13mm split tail with an 11mm rope and it was good, it waws fast when descending, but i cant see that being a bad thing

[kipperfeet]

13mm split tails on a 13mm rope work well with a Blakes hitch because of the amount of pressure that is put on the hitch in one place where the tuck causes most pressure. This is why if you go really fast on it, it leaves really hard glazing in a long line on your rope and melts the split tail at that point.

 

As i remember, it was used alot in America due to thier rope diameter legislation?

 

Over the vast amounts of ropes that we have tried, i have come to the conclusion that the rope make and construction has alot to do with which ropes work well with which friction chords.

 

Even the same rope but a different colour due to the dye can change how the hitch works.

 

Trying to get a gnut to work with some combinations is a swine, but on some ropes it works really well.

 

Also it depends on wether in is 24 strand or 16 strand etc etc.

[Al Duffill]

I use a 13mm climbing line with a 10mm Blakes hitch, never had any probs. I think i would find a 13mm hitch a bit cumbersome, will have to try it. Could I use a 8mm blakes on a 13mm line?

[educated arborist]

if my memory serves me the inventer of the blakes recomended friction cord to be 2mm larger than the rope for optimum performance. But what rupe said is spot on depends on knot, aplication & rope, just try 'em all out & decide for your self. In the uk the smallest permitted diameter for climbing lines & lanyards is 10mm and 8mm for friction cord

[Steve Bullman]

In the uk the smallest permitted diameter for climbing lines & lanyards is 10mm and 8mm for friction cord

 

8mm...this is on the assumption that both ends are terminated at the same point.

[Will Hinchliffe]

The blakes doesnt spread the friction very evenly and places it mostly on one section of the hitch. I would advise you are very carefull if you are descending using a 8mm blakes on a 13mm rope.

[Steve Bullman]

The blakes doesnt spread the friction very evenly and places it mostly on one section of the hitch. I would advise you are very carefull if you are descending using a 8mm blakes on a 13mm rope.

 

as my point above... dont think 8mm would be legal in this case.

[Al Duffill]

as my point above... dont think 8mm would be legal in this case.

 

Didn't think so, wasn't sure though, will stick to 10mm but will defo try 13mm to see how it reacts.