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Nach monatelangem Warten hier nun der erwartete Report

Kurzzusammenfassung :
Gleich mehrere Dinge liefen schief. Der Schlitten wurde an einem neuen, dünneren Seil geführt. Alle bisherigen Tests liefen bei gutem Wetter ab. DER Tag hatte schlechtes. Am Seilende wurde zu wenig Gewicht befestigt, so dass es bei dem einsetzenden Wellengang zu schlingern begann, was die Schlittenführung nachteilig beeinflusste, sprich, der Schlitten verklemmte sich mehrfach in der Seilführung. Dies führte zum Blockieren des Schlittens.  Außerdem wurden andere Flügelschrauben für die Kamerabestestigung eingesetzt, die die Schlingerwirkung verstärkten. Zu allem Unglück kamen ein nicht vollständig gefüllter Hebesack und eine undichte Pressluftflasche hinzu.

http://www.sanluisobispo.com/mld/sanluisobispo/sports/5117370.htm
The report said Mestre's ride down and up on a weighted cable took longer than expected because the cable was lighter then the one used in practice dives and a concrete weight was substituted for a lead one at the bottom. Stormy weather made the cable move more from side to side, which hadn't happened before, the report said. Also, a lift tank was not fully inflated and an air bottle could have leaked, which didn't allow for Mestre's quick ascent to the surface. Instead, she made it up to 540 feet on the sled before Bernabe tried to inflate it with his regulator. Mestre made it up to 394 feet before she blacked out and drifted off the sled. "It is possible that the compressed air bottle used for lift bag inflation was not fully filled, but this factor alone would not have been responsible for all the difficulties encountered," the report said. "It is clear that there was some air in the compressed air bottle. The lift bag, upon inspection after the accident, did show a section of wear that could have been the cause of some leaking."
http://www.iafdusa.com/training/report.htm
In summary, the following conclusions were reached.  There was no single cause for the tragedy that befell Audrey Mestre.  Rather, many different factors, ranging from technology to ocean conditions, contributed to the events of October 12th.  One factor was the new, thinner diameter cable used in this dive.  This new cable was intended to minimize friction with the sled.  However, due to the reduced weight of the new cable combined with a different type of weight at the bottom, the cable was free to move to the side, an effect that was noted by Kim McCoy.  The full impact was not apparent during training dives because of excellent weather conditions.  On the date of the world record attempt, however, the weather was stormy and much windier than during the preceding two weeks of training.  While the waves on October 12th were not in and of themselves so problematic as to require a cancellation, they apparently exacerbated the movement of the cable, resulting in several starts and stops during the ascent.  One of these “stops﾿ occurred at 164 meters, at which time the sled did not move up or down for approximately 30 seconds.
It was also discovered later that a Teflon bushing installed to reduce friction between the cable and the sled appears to have been damaged during a training dive.  An impact between the sled the support boat seems to have compromised the integrity of the Teflon bushing. 
Equally important was the fact that there seems to have been some drift sideways by the bottom weight.  Although a lead weight was used in most dives, on this occasion a concrete weight was used.  In addition, wings were fitted on the camera attached to the sled in order to keep the sled from rotating during descent.  The wings apparently created a lateral force, which continued as the sled descended further down the cable.  The combination of the lateral force created by the wings, the different density of the bottom weight, and the lower drag than usual cable combined to cause inadequate tension on the cable and additional drift of the bottom weight.  As a result, neither the descent nor the ascent was completely vertical, and the sled was forced to advance on a slight incline.  Mr. McCoy found that this incline caused some “hydrodynamic instabilities at low speeds﾿, which in turn led to a “braking﾿ of the ascent bag on the slightly slack cable, exacerbated by surface wave heave movement. 

weitere Infos
http://www.deeperblue.net/article.php/301/2
http://forums.deeperblue.net/showthread.php?threadid=32283

 


 
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