So, the footage has circulated, tests have been done and reports and statements have been published. Where are we on BotBs?
I echo the BCA advice that the BotB is safe to use provided that a cowstail is always clipped into both loops. I will continue to use the knot in my range of personal and professional tools. I think that the knowledge of this method of failure has been there since the BotB came into use, I do think that a number of people were shocked as to the extent of the failure when they saw it. This knee-jerk away from the BotB has calmed down as people have looked into the evidence and scenarios of failure.
Hopefully enough information is out there now to allow cavers to make their own choices on knot application.
A concern may crop up for some riggers where they are leading less experienced cavers or those who simply do no know about the single loop issue. The rigger may descend the pitch and those following could inadvertently clip a single loop placing them at risk of this failure. This scenario perhaps would benefit from the use of a knot that won’t fail if a caver clips a single loop – However the advice to clip both loops does not change.
What if you don’t want to use BotBs?
Well, a number of suggestions have been put forward.
The Fig 8 ‘Bunny Ears’ / Double Fig 8 on the Bight is the most common knot but lacks the ease of adjustment and untying that the BotB has.
The Fusion (Karash) Knot is simple enought to tie but is a struggle to dress on stiff rope and has zero history in UK caving prior to a few months ago.
Alpine Butterflys or Caver’s Butterflys can provide a good Y-hang but an overhand knot would need to be introduced to one of the loops to give a central rescue point.
The Double Bowline on the Bight is one extra twist from the BotB. It adjusts, ties, unties and looks like a BotB, meaning it is easier to use and spot mistakes for existing BotB users.
The choice is down to the individual rigger. The evidence is out there for you to see.
Warning – correct use of Bowline on the Bight Knots
BCA’s Training and Equipment & Techniques Committees would like to highlight the importance of ALWAYS clipping a cowstail through BOTH loops of a Bowline on the Bight knot. Although this has been taught for years by BCA instructors, it appears
that many cavers are not aware of the importance.
The problem is that in a fall the knot can slip in such a way that the rope going down the pitch can actually run all the way back through the knot. This means that a caver falling
at a pitch head with their cowstail clipped into only ONE of the two loops could
potentially plummet all the way to the bottom of the pitch. This cannot happen
if they are clipped into BOTH loops.
A useful tip is for the rigger to leave an HMS karabiner clipped between the two loops to make it easier for the rest of the party to clip in and it is always worth remembering that two cowstails are preferable to one.
From here: http://www.british-caving.org.uk/?page=150
The report from drop tests at BPC on the 30th Jan 2013 is here: http://british-caving.org.uk/equipment/Initial%20results%20from%20a%20Preliminary%20Investigation%20into%20Y%20hang%20knots.pdf
UKCaving discussion here: http://ukcaving.com/board/index.php?topic=14602.msg191183;topicseen#new