rope comparison

S

SRTTech

I just had an interesting experience......all week i've been recreational tree climbing, using Bluewater 2+plus 11.6 mm static line, or my Bluewater Assualt semi static line (same specs as the Bluewater 2 static, but softer rope). I climb using the standard DRT/blakes hitch setup with a prussik foot loop.

I left my 10mm prussick at home today (oops) so i used the end of the line after i tied my figure 8 end knot into the harness. I tied the Blakes hitch, attached the footloop and off i went into the tree. On the way down, i grasped the Blakes hitch with gloved hands and loosened it slightly, slowly rappelling down. Kept smelling melting rope, at the Blakes hitch, so I immediately tied off with my Q.A.S. , and attached my Figure 8 SMC and rapped down. When i got to the bottom. I looked at the Blakes hitch and it was completely melted thru to the core, in mulitple spots (core was fine).

Now compare that to my Bluewater Assault line, i used it all week as well with the Blakes hitch, going up and going down etc. No melting, even when descending on the Blakes hitch quickly. What gives? Bluewater says the Bluewater 2+ and the Bluewater Assault line use the same material for the sheath, yet why did my Bluewater 2+ melt and not the Assault line??????? is it beacuse the Bluewater 2+ is a very stiff rope, where as the Assault is very flexible??

i do longdrop rappels using the Bluewater 2+, with a 6 bar stainless steel rappel rack. The rack gets hot. hot enough to burn skin yet the sheath never melts or glazes......so why did the Bluewater 2+ melt using the Blakes hitch?

comments please! /forum/images/graemlins/confused.gif /forum/images/graemlins/confused.gif /forum/images/graemlins/confused.gif /forum/images/graemlins/confused.gif /forum/images/graemlins/confused.gif /forum/images/graemlins/confused.gif
 
Probably wrong here, but here is my guess.

Using a rappel rack to descend on your Bluewater ropes allows for the heat generated to dissipate while the heat of the Blakes hitch is going to stay right in the spot of the friction. As you have cord on cord in that situation I would say that you are going to generate much more heat because of the friction caused by the cord construction.

I have never heard of Bluewater having an arborist line available to our industry. The rock climbing ropes that they make are not suitable for tree climbing applications as they are constructed differently and react differently than arborist lines. If you are using the static line for SRT ascent into the tree using mechanical ascenders, that is one thing. But I don't think they are suitable for using a DdRT with a Blakes hitch on itself or any other fricion knot for positioning.

However, more than likely I am completely wrong on this.
 
yea the Bluewater 2+ is a stiff, caving and rescue line. The BW Assault is standard ERT/SWAT issue. I've had ZERO problems using the Bluewater 2+ for DdRT, because i normally use a prussick specific (spectra/dynema blend) cord for the Blakes Hitch. Never had any melting, even on a fast rappel witht he prussick cord, until today when i used the end of the Bluewater 2+ to make the prussick......

same with the Assault line, ive Blake hitched it and descended with zero glazing melting, over 50 times. Just seems to be the Bluewater2+ on Bluewater2+ combo that caused the problem.

glad i discoverd it at 50 feet VS 200 though. Here's to muscle memory and quick action drills. I had my Q.A.S. and the SMC fig 8 with ears rappel device attached on the rope in less than 10 seconds, even though the Blakes hitch was still usable, and the mainline was not glazed at all.

When i got home i cut off the tail end of the Bluewater2+ that i had made the Blakes hitch with. The melting was inside where the rope makes the sharp turns in the hitch.
 
What materials are the sheath and core made from in the two ropes? What is their melting point?

I've never used BW ropes but I've read that they are quite stiff. That's not meant as any criticism, just rehashed observations. Could there be an issue with the tight bends in the rope to make a friction hitch?

In general, using static or traditional kernmantle ropes for DdRT isn't favored.
 
the BW Assault line is very flexible and soft in the hand. Its my favorite until i can afford arborist rope. Up here in Canada arborist rope tends to be triple in price compared to the States or Aus.

The BW2+ is stiffer, but i have'nt had a problem, except for yesterday with using the rope to Blakes hitch. I have over 200 treeclimbs on the BW2+ and 51 treeclimbs on the Assault line.

The BW2+ is very prussick or Blakes hitch friendly, as long as you use a seperate rope for setting up the hitch. BW2+ on BW2+ is'nt advised as i found out yesterday.
 
Using the 'doubled rope technique' is much different than using a rack on SRT. When using your rack, for every foot you descend, 1 foot of rope passes thru thew rack. In DRT, for every foot you descend, 2 feet of rope passes thru the friction hitch. The running end of the rope and friction hitch cord both heat up. A by product of friction is heat. The friction hitch will get hotter since it is stationary and the running end won't get as hot since it is constantly running thru.
Also, I noticed you said you were using spectra/dyneema as a friction hitch cord. Very bad idea. They both have an extemely low melting point (297*). They both are excellent at abrasion resistance, but a poor choice for friction. Aren't most repelling ropes made of nylon? Nylon is not the choice of arborist ropes. Polyester is more abrasion resistant, 480* melting point versus 450* in nylon. Nylon looses strength when wet. Polyester doesn't.
There are a couple of inexpensive books you can purchase to learn about arborist climbing.
 
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SRT, are you on a rescue team?

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used to do industrial confined space & tower/structure rescue, using SRT techniques, manhaul tripods, caving/rescue rope, rappel racks, skedco litters, haul pulleys etc. Have done multiple solo pickoffs of injured or scared new rock climbers on small crags, Branched out from there to solo longdrop rappels, night rappelling (bridges), and trained briefly with a ex UK Marine in SRT Tactical rappelling/ building entry. Branched out a year ago to my own Hybrid style combination of SRT & DRT tree climbing, have recently branched out again to just DRT treeclimbing.

as for rescue, i no longer work in a industrial setting, but i do volunteer for line searches. Last one was several years back, looking for a young girl that had been kidnapped/raped and was later found in a local lake, weeks later. Something like 1000 volunteers combing the Lower Mainland.
 
[ QUOTE ]
Using the 'doubled rope technique' is much different than using a rack on SRT. When using your rack, for every foot you descend, 1 foot of rope passes thru thew rack. In DRT, for every foot you descend, 2 feet of rope passes thru the friction hitch. The running end of the rope and friction hitch cord both heat up. A by product of friction is heat. The friction hitch will get hotter since it is stationary and the running end won't get as hot since it is constantly running thru.
Also, I noticed you said you were using spectra/dyneema as a friction hitch cord. Very bad idea. They both have an extemely low melting point (297*). They both are excellent at abrasion resistance, but a poor choice for friction. Aren't most repelling ropes made of nylon? Nylon is not the choice of arborist ropes. Polyester is more abrasion resistant, 480* melting point versus 450* in nylon. Nylon looses strength when wet. Polyester doesn't.
There are a couple of inexpensive books you can purchase to learn about arborist climbing.

[/ QUOTE ]

i am aware of the heat buildup in prussicks/blakes vs the hat dissapation of the racks, just never expereienced a melt like that before with the BW2+....like i said before, ive descended with blake hitches on other static ropes with ZERO problems, and descended on the BW2+ with different cord for the blake hitch with zero prob, it was just the Bluewater2+ on Bluewater2+ that melted the first two wraps of the blakes.

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