by Scott McCrea » Oct 19, 2005 10:02 pm
Originally published in the October 2005 issue of NSS News (vol 63, #10). Posted here with permission from the author.
Another Bobbin Issue Diagnosed
By Andrew Howe NSS #49198
I recently did a 259 foot drop on an easy bend rope with my bobbin and experienced an issue I felt should be reported to all. I’ve previously done even longer drops (350’) on my bobbin without any issue besides having to feed the rope, so I didn’t think much of doing this drop.
What happened was the sheath got pushed down the rope making the rope fatter. I was the third person down and the sheath had been pushed down enough to make it too thick to feed through my bobbin. This occurred at perhaps the midway point or just below it.
Once I recognized what was slowing then finally halting my descent, I was able to stretch out the sheath beneath me, thus allowing the short section of tightened rope to feed properly. The process was: push the sheath, then feed the rope through the bobbin. However, in my case, by the time the problem was bad enough to halt my descent, little feeding was necessary.
Part of the problem was also due to the spools on my bobbin. They are very well used and thus the grooves are rather deep. As one might imagine, they are only the width of a tightened rope, thus they created a bottleneck for the fattened rope.
This was not a problem with subsequent descents that day on shorter rope, so the spools themselves are still completely functional on tight rope.
If one knows they will be doing a long single drop on a rope that has the potential to have the sheath bunch up, they should consider using fresh spools in their bobbin. But be careful on your new spools: fresh spools won’t have as much contact with the rope and therefore will have less friction, so the bobbin will be much faster on rope than you’ve grown accustomed to!
Of course, a rack is much better on descents like this one, so the better practice would be to avoid bobbins in long drops altogether.
Personally, I have never heard of this happening. Cheers to Andy for sharing his experience.