fishermans v splice

[skyhuck]

the fishermans choked the rope and thats were it snapped it. snapped twice in the same place. also done some splices with eyes just big enough for the carabiner-the small eyes snapped open at approx

6ookgs lower than big eyes, if you get what i mean.

 

This is interesting stuff! Cheers again:icon14:

[DrewB]

This is interesting stuff! Cheers again:icon14:

 

no worries!!!!!!!!!!!!!

[Marc]

What about a bowline? I heard this knot doesn't lower the strength as much as say a fishermans.

 

I only use fishermans for eye 2 eye hitch cords and my lanyard where i don't expect to be putting massive loads on it, certainly not loads of over a ton.

 

Still intresting to know.

[Jamie]

I'm intrigued to find out that the smaller (tighter) eyes broke at lower loads. I'd have assumed that the bend radius would be similar around the anchor point. Were the eyes tested with the same anchor or did the large eyes drop over a bollard with a larger diameter and the smaller eyes attach via a carabiner? I'm trying to figure out why the smaller eyes failed.

 

I've found splices tend to fail at points where the taper changes. either at the end of the taper or (when i broke some tenex using samsons instructions) at the initial taper halfway down the bury just after mark one

 

Jamie

[Jamie]

here is some text copied from a paper on all about knots.

 

Strong Knots

Blood Knot 85–90% (Barnes); 80% (Day)

Flemish Bend 81% (Frank and Smith)

Figure Eight Loop 80% (Frank and Smith)

Double Fisherman’s 79% (Frank and Smith)

Moderately Strong Knots

Butterfly 75% (Frank and Smith)

Bowline 60% (Day)

Overhand Knot 60-65% (Luebben )

A Weak Knot

Overhand Bend (My guess is less than 50%)

 

I'm assuming the names in brackets are other authors

 

Jamie

[Bob Rolfe]

i think ill still use my fishermans though as a spliced eye must wear more i would of thought due to the constant wear being directly on the exact same spot all the time. With a fishermans it changes slightly with every new knot. also you can if needed cut a foot off the end of your rope and start a fresh. some of us lesser mortals cant splice anything other than 3 core although in saying that good post

[Dean Lofthouse]

I have a steel carabina fisherman'd onto the lowering rope and that does take a pounding, although I imagine that if the breaking strain was over a ton for climbing line, it's going to be very high for lowering rope.

[Jamie]

according to proclimber. Samson 13mm Stable braid has a average strength of 4717kgs. Using the figures i quoted above a bowline would drop that strength down to 2830.2kgs. thats a seriously big bit of wood.

 

Jamie

[DrewB]

from seeing the tests done i firmly believe that our bodies will snap or our anchor point will fail before even a fishermans breaks-its nice to know we climb with super strong safety margins.

jamie-apparently when the eye is too small it compresses the fibres where they go back into themselves at the splice (i didnt really understand why), i expected the break to be at the taper too. but making the eye bigger did increase the strength so it must of worked.

[Ropey]

That a nice looking rope you have there Drew

 

I have some data on the effect that Knots and Splices have on ropes that you may find interesting.

 

This information was published by the Department of Scientific and Industrial Research.

 

Reduction of strength caused by knots and splices on synthetic ropes.

 

Ropes made from Nylon

Reef Knot - Ave 55.6% loss of strength

Sheet Bend - 47.8%

Bowline - 31.8%

 

Splice - 10.9%

 

Ropes made from Polyester

Reef Knot - Ave 47.3% loss of strength

Sheet Bend - 47.5%

Bowline - 32.0%

 

Splice - 13.9%

 

These were results from standard ropes. With the more modern core dependant type ropes i.e. kermantle and the cover dependant 16 plait ropes greater retention of strength can be obtained as drew has found.

 

Common sense is required with any splice or knot. Constant inspections should be made on all ropes and if they show signs of damage they should be retired imediately.

 

Replacing your rope is cheaper than loosing your life!

 

Happy Climbing..................................................