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Abbo · 25th November 2007, 05:22

There is a well-worn argument that says that though rebreathers are clearly more dangerous than OC in shallow waters, they are safer at trimix depths - and yet they tend not to be used in depth record attempts. What range of depths is the sweet spot where CC is safer than OC?

The deepest dive on OC is 330m: the deepest on CC is 270m. Dave Shaw's write up of his October 2004 dive to 270m in Boesmansgat in South Africa..
http://www.deepcave.com/images/Boesm...h_Oct_2004.pdf
..describes almost leisurely line-laying and exploration at this extreme depth. Nevertheless, clearly WOB and scrubber duration were problems, and seem likely causes of his tragic death in a working dive at the same depth early the following year. Though large radial scrubbers should overcome some of the duration problems, the significantly higher WOB of RBs seems pretty hard to engineer out. Beyond a certain depth I would have thought the higher WOB represents a serious hypercapnia risk on CC. Will we ever see rebreather divers setting depth records, or are they really inferior tools at extreme depth? -If so, at what kind of depth do you think OC starts to win out again over CC for safety?

25th November 2007, 05:22	#1 (permalink)
Abbo Going down on Meg Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 427	Will OC records always be deeper? There is a well-worn argument that says that though rebreathers are clearly more dangerous than OC in shallow waters, they are safer at trimix depths - and yet they tend not to be used in depth record attempts. What range of depths is the sweet spot where CC is safer than OC? The deepest dive on OC is 330m: the deepest on CC is 270m. Dave Shaw's write up of his October 2004 dive to 270m in Boesmansgat in South Africa.. http://www.deepcave.com/images/Boesm...h_Oct_2004.pdf ..describes almost leisurely line-laying and exploration at this extreme depth. Nevertheless, clearly WOB and scrubber duration were problems, and seem likely causes of his tragic death in a working dive at the same depth early the following year. Though large radial scrubbers should overcome some of the duration problems, the significantly higher WOB of RBs seems pretty hard to engineer out. Beyond a certain depth I would have thought the higher WOB represents a serious hypercapnia risk on CC. Will we ever see rebreather divers setting depth records, or are they really inferior tools at extreme depth? -If so, at what kind of depth do you think OC starts to win out again over CC for safety? Last edited by Abbo : 25th November 2007 at 11:25.
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