Run times in cave diving

[Mark Chase]

Originally Posted by [b

Quote[/b] (wetlettuce @ Sep. 11 2003,16:38)]

Originally Posted by [b

Quote[/b] ]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.

I didnt actualy rack up much deco on the bounce  only 15mins in fact. It was the 50m ledge and the ascent that got me. I left the ledge with 24mins deco and I racked up another 10mins deco ascending to 22m. The profile reflects that the whole dive was done on back gas as Nitrox was not available in Gozo in those days. Air is not a good deco mix . I didnt start loosing deco untill I hit 9m it just stayed at 33mins.

The dive was follow the sea bed out and the sea bed back to the reef so the sea bed dictated the deco profile. Untill I hit the wall at Requa point at  about 22m. My ascent rate was 2.5m/min with stops at 21, 12 and 9 and deco at 6m. The dive was on two independent 10's of Air.

Note: I dont do this any more as its silly and dangerous but it was the last obvious bounce dive I had on my PC.


ATB

Mark Chase

[Pierre Farrugia]

<font color='#0000FF'>Hi Mark,

I know the place perfectly, infact it there where I did my trimix course dives !

Michael,

So you are in the serious business, that's good to know that on this forum we have very experienced divers who push the envelope. Also you do deco with 02 at 9m because you use a habitat or you use this even in water ? Maybe I am mistaken but do you dive DIR?, if yes is this permitted in DIR to decompress this way? Also is it commen no respect oxygen clock as I think a dive this big you go more that 100%CNS , which I think is normal for big dives. Hope you don't think I am trying to be critical but these question cannot be asked to anyone! &nbsp;

Regards

Pierre

[Bob Cooper]

Originally Posted by [b

Quote[/b] ]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.

I don't think there is any such thing as the &quot;average cave dive&quot;.  Michael has shown us some really serious dives here (thanks Michael, very interesting). Obviously, the average cave dive (not like what EKPP are doing) is governed by gas.  The reason we can spend longer in a cave than in the ocean is due to the stable environment and the use of stages. But it's all relative.

Imagine a double stage dive in a (relatively) deep cave.  Ressel for example.  The weekend cave diver (like me) would need 4 bottles for this, 2 stages of back gas, a 50% bottle and a 100% bottle ( and maybe a scooter or two!)  You wouldn't want to carry that lot in the ocean!  Differrence is, you drop your 100% bottle at 6m, your 50% bottle at 21m and continue with 2 stages.  The first stage you drop at approx 120 bar, then you might drop a scooter, the second stage you drop at 120 bar and then continue on backgas (although we tend to just use the stages and leave the backgas intact).  This gets you further into the cave and hence prolongs your BT.  Think of the extra gas you have available to you!

Imagine you have a &quot;team&quot;.  The team will set up a big dive for you by dropping the stages (and maybe scooters) for you, meaning you don't need to swim or scooter with them.

All this results in longer BT's and hence the &quot;bounce dive&quot; term for (relatively) short ocean dives, although as Michael said, it's not a derogatory term.

Remember that what is a &quot;big&quot; dive to me is a little bimble to somebody like Michael.  Earlier this year in France a couple of our team attempted a &quot;big&quot; (too big for me!) dive at Ressel. I just dropped their 6m bottles for them and did my own dive with my own buddies.  They had some problems and had to abandon some gear. If I remember correctly this was at about 1500m penetration and at a depth of 70m.  A couple of days later, some of Michaels team retrieved their gear on a &quot;little&quot; training dive.......!

Like I said, it's all relative.

Michael - good to have you on here. I hope you will be able to contribute to some of this stuff.

Bob

[Bob Cooper]

Originally Posted by [b

Quote[/b] ]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.

I don't think there is any such thing as the &quot;average cave dive&quot;.  Michael has shown us some really serious dives here (thanks Michael, very interesting). Obviously, the average cave dive (not like what EKPP are doing) is governed by gas.  The reason we can spend longer in a cave than in the ocean is due to the stable environment and the use of stages.

Imagine a double stage dive in a (relatively) deep cave.  Ressel for example.  The weekend cave diver (like me) would need 4 bottles for this, 2 stages of back gas, a 50% bottle and a 100% bottle.  You wouldn't carry that lot in the ocean!  Differrence is, you drop your 100% bottle at 6m, your 50% bottle at 21m and continue with 2 stages.  The first stage you drop at approx 120 bar, the second you drop at 120 bar and then continue on backgas (although we tend to just use the stages and leave the backgas intact).  This gets you further into the cave and hence prolongs your BT.  Think of the extra gas you have available to you!

Imagine you have a &quot;team&quot;.  The team will set up a big dive by dropping the stages for you, meaning you don't need to swim or scooter with them.

All this results in longer BT's and hence the &quot;bounce dive&quot; term for (relatively) short ocean dives, although as Michael said, it's not a derogatory term.

[malcolm smith]

I am probably more of a cave dive bimbler than Bob and have been happy with just twin 12s and a deco bottle in France.
There are some lovely shallow dives there, and 90mins or so is a very nice relaxing dive.
One has a max depth of approx 7m, so you don't have to be a deco monster to enjoy it &nbsp;

Cheers, Malcolm.

[db8us]

I agree with Malcolm, there are really nice shallow dives in France, like the Trous Madame...

About beeing DIR: Yes i guess i am and yes it is DIR to use O2 on 9m, BUT only in a habitat (dry environment).
About the CNS%. I never look at them, since we often have more than a few thousand maybe.
General rule is not to fry your lung during bottomtime, means keep pO2 low and during deco follow the gas-break-rules.
When beeing in water we use O2 from the 6m stop upwards.

Hey Bob, you dive with Ian Pinkstone and the gang ?
Hopefully we will meet in France one day !

[Bob Cooper]

Originally Posted by [b

Quote[/b] (db8us @ Sep. 12 2003,07:22)]

Originally Posted by [b

Quote[/b] ]Hey Bob, you dive with Ian Pinkstone and the gang ?
Hopefully we will meet in France one day !

Yes, that's right. We were there for a week in May. &nbsp;I think you were there just after us? and pulled Ian and John's gear from somewhere near the end of S1? &nbsp;We will go back next year for another week. &nbsp;I think Ian spends as much time in France as he does in UK!

Bob