Confused, Why should cave divers not dive to an excessive depth?

[Brian Pasic]

Why should cave divers not dive to an excessive depth like open water divers can?
I've heard this from a buddy of mine who said this is the rule but he wasn't sure why and therefore I am not either.
Very curious about this because I figured water is water right?

thanks!

 

[knowone]

Slight horizontal distance depth inclinations?

 

[Brian Pasic]

ya im stumped too. i wonder if its something deeper than that, pardon the pun.. lol

 

[Session Eleven]

The further you are in a cave, the longer it will take to get out in the event of an emergency. Some cave divers penetrate quite far in, sometimes thousands of feet.

The deeper your depth, the longer it will take to surface. If you snag a deco obligation, your ascent becomes even more lengthy and involved.

While neither of these diving complications are overly risky on their own (with proper training), I imagine combining them is only for the most talented/foolish.

Note: I have no experience deep diving or cave diving, but I did stay at a Holiday Inn Express last night.

 

[currier]

Unless otherwise trained and carrying the appropriate gear, a cave diver should still adhere to recreational 40m "depth" limits ... but penetration INTO the overhead environment is factored on top of your current depth -

So, a diver who is 25m deep should only be able to penetrate 15m into an overhead ... or say, with a depth of 15m, 25m penetration -

40m limit in these cases is 'clear line' (so to speak) to surface.

Please correct me if I'm wrong here, guys - I'm not cave, wreck, or tech trained - I just read a lot on SB

 

[Cave Diver]

Unless otherwise trained and carrying the appropriate gear, a cave diver should still adhere to recreational 40m "depth" limits ... but penetration INTO the overhead environment is factored on top of your current depth -

So, a diver who is 25m deep should only be able to penetrate 15m into an overhead ... or say, with a depth of 15m, 25m penetration -

40m limit in these cases is 'clear line' (so to speak) to surface.

Please correct me if I'm wrong here, guys - I'm not cave, wreck, or tech trained - I just read a lot on SB

I believe you're talking about cavern restrictions. Full cave carries no such linear restriction.

One of the "golden rules" of cave diving is not to exceed the depth for which you're trained and have appropriate breathing gas for. Other than that, I've heard of no such depth limitations on caves. There are several caves that rapidly exceed recreational depth limits (Eagles Nest comes to mind) that are frequented by cave divers.

No clue on the source of the OP's information, as it's been presented.

 

[rongoodman]

Depth considerations are one of the five basic rules of cave diving safety originally summarized by Sheck Exley, along with required training, maintaining a continuous guideline to the surface, proper gas management, and redundant lights. At the time they were formulated, it meant caution when diving deep on air, along with not violating the MOD of your breathing gas. Being narced in a cave while dealing with an emergency would be a Bad Thing, and just recently a very experienced WKPP diver died after inadvertently breathing a deco gas below its MOD. Even with modern gases, such as trimix, and deco procedures, deeper dives can be more complicated due to lack of direct access to the surface, since your ascent profile has to go where the cave goes, rather than just following the nice schedule to the surface that the software plans out for you.

 

[TSandM]

Sounds like the OP has run into Sheck's rules of accident analysis. In addition to lack of training, lack of guideline, not observing gas limits, and not having enough lights, diving to excessive depth was implicated as a cause of cave diving fatalities. Basically, this really isn't depth per se; it's END. The cave environment can be a very complex one, requiring significant situational awareness to remain oriented. Narcosis affects one's ability to reference the cave, and to remember intersections (or sometimes even recognize them!).

I have personal experience with the dulling of perception that can occur with narcosis, and I fear it greatly. As a result, I have made a personal decision that I will no longer dive any cave below 80 feet without a helium mix. Most cave divers in the modern era use a 100 foot END as a limit. (END is "equivalent narcotic depth". When helium replaces some of the nitrogen, it reduces the narcotic potential of the gas by an equivalent amount.)

 

[Brian Pasic]

Thanks guys. i guess what i wanted to know if there was something more fundamentally different about the very makeup of the cave water itself. Caves are a challenge in decent and especially ascent due to decompression restrictions and air supply. And it seems the effects of nitrogen narcosis are more critical in a cave.

 

[Cave Diver]

Thanks guys. i guess what i wanted to know if there was something more fundamentally different about the very makeup of the cave water itself.

No.

Caves are a challenge in decent and especially ascent due to decompression restrictions and air supply. And it seems the effects of nitrogen narcosis are more critical in a cave.

Yes, it can be. Narcosis can easily lead to navigational decision mistakes, or cause you to not pay enough attention to your remaining gas, or not notice a gear malfunction, or...

There is the added detriment that in a cave, you often won't have the option of ascending enough to alleviate the symptoms of narcosis. Depending on the particulars of the cave you're diving, you may find yourself having to travel a fair distance just to ascend a little bit. Another factor worth considering is that the flow level of some caves can increase your workload, which may cause you to start retaining some CO2, multiplying the narcotic effect and causing a "dark narc."