Technique
Technique
October 2005 06/132
Two divers conducted a series of dives together. One of the divers normally used two dive computers but dived with just one because the other had a flat battery. The other diver used a computer that she had recently bought second-hand. On the third day of a five day trip both computers indicated that decompression stops were required. They stopped at 6m for about 5 min; the second-hand computer cleared first and then the other. Once back on the boat the second-hand computer sounded an alarm and locked itself. The following day they dived to 35m. On ascent both computers indicated a 2 min stop at 9m followed by a 18 min stop at 6m. At this point the second-hand computer indicated that a further 17 min was required whilst the other diver's computer had cleared. They had previously concluded that the second-hand computer must be faulty and the two divers decided to ascend. The second-hand computer was checked and no fault was found. Two weeks later they conducted a dive consisting of 30 min at 20m and 15 min at 7m. 1 hour 30 min later they dived to 20m for 56 min. Towards the end of this dive the second-hand computer indicated that 20 min of stops were required whilst the other diver's computer had 2 min of no-stop time left. Again it was assumed that the second-hand computer was at fault. Subsequent to the dive the divers consulted diving tables and realised that the second-hand computer had been correct and that the other diver's computer must have been wrong. Examination of this computer then revealed that it had been set to nitrox 38. The divers had been using air. It is thought that the setting had been changed by the computer being left wet, in a bag, and on a moving boat. It was suggested that the boat's movement may have caused the appropriate wet terminals of the computer to have been contacted thus resetting it incorrectly.
November 2005 06/046
Three divers commenced a night dive in a quarry. Some time into the dive two of the group saw the third diver sinking rapidly and they lost contact with him. They surfaced and raised the alarm. Surface and underwater searches were conducted. The third diver surfaced safely about 25 min later having joined up with another pair of divers who were unknown to him. He realised his mistake when he became separated a second time. No ill effects were experienced.
March 2006 06/071
A diver was on a rebreather training course at a depth of 20m. He inhaled water and began to panic. The instructor gave the trainee his alternative air source and they made a rapid ascent to the surface. Their dive duration was 20 min. Both were placed on oxygen. No subsequent ill effects were experienced.
April 2006 06/085
Two divers were engaged in a training course. They completed one dive and 50 min later started another. They were on a wreck at a depth of 15m when the regulator of one of the divers started to free flow. The instructor offered his alternative air source but the diver spat it out. The instructor then offered his main regulator; taking the octopus regulator himself. Again the diver refused. While this was happening they dropped over the side of the wreck and sank to 22m. The instructor brought the diver to the surface. They made a faster than normal ascent. At the surface the diver who had had the free flow fell unconscious. He was recovered from the water and first aid and oxygen was given. The diver recovered. He was taken by ambulance to hospital from where he was discharged later that day.
June 2006 06/188
A diver planned a dive to 35m to extend her depth experience. She had previously dived to 31m. During her pre-dive checks she found that her pony regulator was leaking air slightly. She agreed with her buddy that she would dive with it switched off and that the buddy would turn it on again if it was required. At the bottom, they found themselves in a current and the diver became concerned that she could not keep up with the dive leader. Her breathing rate increased. She managed to calm herself down but was concerned that if she did need her pony cylinder she could not turn it on on her own. The dive leader stopped and came back to her and they exchanged 'OK' signals. The dive leader signalled that she wanted an air check. The troubled diver was unable to find her gauge, which had become unclipped. The dive leader thought that they were both suffering the effects of narcosis and signalled that they should ascend. The dive leader took hold of the troubled diver and used a controlled buoyant lift to help her up to 20m. At this depth the troubled diver found her contents gauge and realised that she had enough air to complete the dive; this allowed her to become more calm. The dive leader deployed a delayed SMB and they made a normal ascent including safety stops. Their dive duration was 38 min. No subsequent ill effects were reported.
June 2006 06/249
Three divers dived on a wreck at a depth of 13m. Towards the end of the dive one of the three deployed a delayed SMB and they drifted off the wreck. The diver with the reel then lost control of his buoyancy and rose to 7m before he was able to regain control. He remained at that depth and completed decompression stops before surfacing. One of the other divers attempted to stop his ascent but was unable to do so. The other divers remained on the bottom, deployed another delayed SMB and then made a normal ascent. No subsequent ill effects were experienced.
July 2006 06/164
A diver was testing a rebreather in a swimming pool after a mouthpiece replacement. Within 2 min underwater his breathing became laboured. He switched to open circuit and then back to closed circuit. He conducted a diluent flush. All seemed correct but then he became breathless again within 1 min. He switched to open circuit and swam into the deep end of the pool. He switched back to closed loop again and very quickly went back to the same problem. He stated that he felt as if he was "breathing through a straw". He switched back to open circuit and left the pool. Shortly afterwards he developed a bad headache. He subsequently discovered that the scrubber cartridge was empty. He had forgotten to re-fill it again after its last use.
August 2006 06/185
A pair of divers conducted a wreck dive to a maximum depth of 46m. They used twin 12l cylinders containing nitrox 26 and carried nitrox 70 for their decompression. The sea state was rough and underwater visibility was low. They descended a shotline to the wreck. The lead diver attempted to turn on his main torch at 25m but it had failed. He used a back up torch and the other diver took the lead. They swam above the seabed at a depth of 45m towards the bows of the wreck. Visibility was about 3m but the light level was very low, with only items in the torch beams visible. They swam down the side of the wreck, about 2 to 3m away from it. 11 min into the dive they realised that the side of the wreck could no longer be seen. They assumed that they had swum away from the wreck and they turned towards it and swam on. What they did not realise at the time was that they had been swimming past a very large hole in the wreck and had turned and were now swimming into the wreck itself. They found a wall and followed it. 13 min into the dive they came to a junction with two other walls, and found themselves trapped in an enclosed space, unable to ascend or back out. The divers became panicked. One of them accidentally kicked and dislodged the mask of the other and they became separated. One of the pair saw a hatchway below him and swam down. He found the seabed and moved forwards until he could see clear water above him. He waited outside the wreck for his buddy. When his buddy did not appear he deployed a delayed SMB and tied it off on the wreck. He then tied another reel to the wreck and made his way back inside to see if he could find his buddy. After a while he realised that he was not going to find him and made his way back out. He then made his way to the surface completing 24 min of stops on the way. His total dive time was 66 min. The other diver took longer to escape from the wreck and he surfaced missing 14 min of stops; he was placed on oxygen. The emergency services were alerted and the diver who had missed stops was given precautionary recompression treatment.
Page last modified: 21st Dec 2006 - 17:48:47