Incident Report

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Incident Report 2020-05-01T16:26:00+00:00

The potential danger using a diving knife

Incident Date

1906-06-06

Incident Description

My report does not involve an incident per se more a problem found when using a knife for line clearing. In 1991 Rob Parkers line was found to have been swept back into the chamber at -54m in the terminal sump at Wookey. In 1996 I made a dive to this point to establish the extent of the problem coupled with the aim of solving it and continue exploration. At -51m I was stopped by a large tangle of line. This line was soaked in sediment having been underwater for 21 years. Attempts to remove the line resulted in a complete blackout. It was at this stage that I realised the potential pitfalls of using a knife for line cutting. Being right handed I held the knife in my right hand. My left hand held the section of tangle I was wishing to cut away. As I was in a very poor vis situation it also somewhat crucially held the out line. I became intensely aware that if I cut the wrong piece I could be in serious trouble especially considering the depth. In the blackout combined with loss of sensitivity because of the neoprene gloves and the lack of alertness caused by the narcosis I decided to not cut the line of the tangle but drag as much as possible behind me to a shallower depth where hopefully the vis would improve allowing me to make the cut and remove albeit a small part of the tangle. The vis actually deterioated and once again I was faced with the same dilemia. Several strands of line in the left hand one of which I must not cut. Bugger which one was it again? At this point I cable tied the line around me into a bunch and left.

Lessons Learned

Whilst decompressing the idea occured to me that not even touching the line would help maintain the vis. However a knife normally needs the diver to hold the line being cut. But what about a good pair of scissors. After some highly successful practise the next dive allowed me to simply cut the remaining tangle into short lenghts in situ where it gently floated harmlessly to the ceiling. At all times my left hand was on the out line and I removed all of the remaining tangle. With the tragic loss of a diver in Lower Birkwith quite recently I realised that dive knives are a very inadequate tool still being used by a large number of divers. If one finds oneself in a low bedding and the line becomes tangled around a cylinder valve or worse a leg/fin it may prove physically impossible to have the one hand hold the line to be cut whilst the other does the cutting with the knife. Scissors or a pair of shears could be used to snip the ensnaring line single handed whilst maintaining that all important hold on the out line. I think of the tragedy in 1974 in the terminal sump of Agen Allwedd when a experienced diver was lost after being forced to cut the line possibly as a result of entanglement. It would seem the most likely scenario that immiediatly following his cutting of the line he lost contact with the end which led to safety. I would like to believe that if this situation occured again a successful outcome would be achieved by the use of scissors and that all important hold being maintained on the out line. Several recomendations where made following the Lower Birkwith incident with scissors/ shears being an option to consider. I firmly believe that they should be considered a more compulsory piece of equipment and that dive knifes should be considered a thing of the past.
Factors
Line Management Major
Gas Management Unknown
Equipment Management Unknown
Equipment Failure Unknown
Training Unknown
Medical Unknown
Planning Unknown
Procedural Error Major
Cave Environment Unknown
Weather Unknown
Other Factor