Run times in cave diving

[Mark Chase]

Over several threads now I have noted the comments reguarding run times in caves being substantial and ocien diving being bounce dives due to short run times?

So just how long is the average cave dive? I would have thaught all cave dives were bounce dives as you go in to a fixed point set by plan or gas limits and turn round and come streight back out.

On my ocian dives I plan for decent to depth and available back gas on twin 12s. I aim for a minimum of 40min bottom time down to 65m with a prefered profile of 1hour on the bottom and all times in between bassed on available gas water temp and deco comitments.

Doing this I am running average 95min dives with a few in the 120 to to 140min bracket. Only a few of the divers in my group are pushing 120 plus but 90 is accepted norm.

My discription of a bounce dive is decend to silly depth imediatly turn round and come home

just curious

Mark Chase

Typical bounce dive

[db8us]

The Vyper stopped on the last cave-dive after 999Minutes (as he usually does), but bottom time was around 8 hours, the rest deco and traveling in the shallow...

[db8us]

Here is another one, two weeks earlier than the above profile.
A bit deeper and a lots of ups and downs.
Bottomtime was around 300 Minutes plus the usual deco.

[Mark Chase]

GOSH

Did you have a habitat for this dive?

This obviously is an extreem example I dont think many people could do 16+ hours in the water but what sort of run times is your average cave diver doing on the average tec cave dive. ie one that runs into stages and deco. I am sure you can apreciate the diferance between a Saterday Trimix wreck dive at 90 mins and a 125m deep wreck with 9 hours of deco so what would a cave diver do as a run time on a saterday trimix or long deco dive.  

Mark Chase

[Dominic]

8 hours plus deco??
Don't you have anything better to do?

[And]

<font color='#0000FF'>Hi

DB8us is Michael Waldbrenner, of the EKPP. He partnered Reinhard Buchaly (the inventor of the RB80) on those dives with twin rebreathers and twin 20 litre cylinders. (Well, at least the first one he did, not sure about the second)

You can find more details of EKPP's dives on www.ekpp.de and even order a DVD for 15 euros (which I have and its very good) but yes, they do use a habitat, along with heating units etc. as the water is only 10 degC

Andy

[Darren A]

I remeber some time ago, that someone who visited the pot was told that sawtoothing, even by 2 or 3 metres, throughout a dive could provoke a DCI hit. How on earth do you get away with 30-50m sawtoothing?

Edit:- D'oh, just realised thats probably feet isn't it &nbsp;

[And]

<font color='#0000FF'>Hi

No its metres.

Look at the deco curves and compare with the graph Mark posted. They are quite a bit different. The use of a habitat allows higher O2 exposure as you are warm and dry. They just do the deco properly and use the right gasses. Caves quite often produce sawtooth profiles.

We all know there are fast tissues and slow tissues, the fastest being the alveoli in the lungs and the slowest being cartilage etc. in the joints. If your bottom time is below 30 minutes then some of the tissues haven't really started ongassing yet and so the deco requirements are less than a prolonged exposure at depth.

From commercial diving there were two terms, bounce dive and saturation dive. The bounce diver used diving bells and decompressed in the water, the saturation diver worked longer at depth and then got to the surface and immediately went to the chamber and did a lengthy decompression there.

In the EKPP case the tissues are obviously more saturated and the deco is done pretty much as a saturation dive with the use of a habitat etc. the same can be said of the big WKPP dives.

In a typical wreck dive the unstable environment simply means it isn't possible for a recreational diver to be at depth long enough safely for the exposure to saturate the tissues and is therefore a bounce dive. That is not to say that all cave dives are saturation dives because they aren't, its all down to tissue saturation.

Its also not specifically a DIR thing more to do with commercial diving jargon carried forward into rec diving due mostly to the fact that the deco tables were primarily created for the commercial diving industry.

I might be wrong so feel free to correct me.

Andy

[db8us]

Yep, wetlettuce is right, it is in meters.

I know that these are not typical &quot;weekend&quot; files, but i wanted o show what is possible deco-wise if you use the right tools and gas and methods.
Deco is, whenever possible, in a habitat on O2 at 9m.
You have to take care about gasbreaks then of course.

We do maybe 4-8 longs dives per year, where i would call everything long that is more than 4 hours.

As bouncedives i would count Bottomtimes of less than one hour and shallower than 100m.

But i would never use the word &quot;bounce&quot; in a negative way, since most fun and/or wreckdives are bouncedives and i still love that.
The deco from a bounce is more difficult since if it a saturation dive is it always about the same...

About the sawtooth:
Yepp, you have to be careful, so whenever we have to go &quot;really up&quot; we either do it fast and/or do some deep-stops.
Also you have to think about the deco-ceiling.

The problem is: when cave has a sawtooth profile, we have do dive a sawtooth &nbsp;

We called the last Gourneyrasdive
http://www.ekpp.de/projects/gourneyras03_07/index.html
when the cave was going vertical upwards again after laying 400m of new line and survey it out.

You just need a reason to call the dive &nbsp;

With &quot;bounces&quot; i think more people get bend because they rely on their computers, but i am sure this horse has beaten to death here on this forum...

Michael

[db8us]

Originally Posted by [b

Quote[/b] (Dominic @ Sep. 11 2003,16:19)]8 hours plus deco??
Don't you have anything better to do?

Better to do ?
We eat and have fun, means exchanging jokes in Wet-Notes, play games...whatever.
Also you have to be alert and watch your buddy, check gear, etc.
I would not say it is boring....