Re: Jablonski's presentation.

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Posted by Kendall Raine on March 05, 2001 at 16:15:58:

In Reply to: Jablonski's presentation. posted by Gerry Smith on March 05, 2001 at 15:38:15:


Please see my post to Frank on streamling. The basic message for recreational diving is that all the really mission critical nuances used in a 3.5 mile push at 300 ffw become more matters of comfort and relaxation on a dive at Catalina than life and death issues. They don't go away; however.

Streamlining, for example, means no extra drag or snag. Swimming with drag requires a lot of work-the comment about the drag/work relationship came from Mark Londsdale. More work causes stress, CO2 buildup, inert gas loading, increased consumption and a less pleasurable dive. This is all intuitive. Even the issue of using a wing versus just using a backpack without a wing involves drag. Those, like Chris Grossman who dive just the back pack without a wing claim the lack of wing makes them more stream lined. That's true. However, it also works against them inasmuch as they must keep swimming to maintain position in the water column since they're inherently negative at least at the start of the dive. The need to swim means they also need to maintain hydrodynamic lift from the swimming. That means the need to plane slightly upwards in order to exert a force to counter the negative buoyancy-like a nuclear sub which need headway to stay level at great depth. That slight plane is drag. The result is all that's saved in terms of work from not having the wing is given back, and more, by having to constantly plane up to maintain depth. I know, I've tried both systems.

hope this helps,


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