Bent at Ginnie?

[PfcAJ]

It seems that there have been quite a few people getting bent (to some degree) at Ginnie. I have heard of at least 6 people, and I personally know a few of them. What is so special about Ginnie that causes this high number of incidents?

Improper decompression? Obviously. But even when people are within the parameters of their tables or computers, it's still happening.

Lack of proper hydration or nutrition? Maybe. But wouldn't we see a similar frequency at other caves?

Lack of diver skill? Once again, possible. However, we would still see divers unable to hold stops and stay true to a schedule getting bent at other sites, which just isn't happening nearly as often.

So what could it be? Brian (Litehedded) and I have been doing some thinking (and consulting with other local cave divers) about what is so specific to Ginnie compared to other places. We have determined that the first few hundred feet of the cave is the most likely culprit.

The cave will be referenced from the exiting diver's point of view:

The depth change from the Junction Room area to the breakdown room past the Keyhole is about 15-20ft. This is a rather high percentage change that occurs quite quickly. Divers with longer bottom times may have more drag associated with them (stages, scooters) that increases their exertion on exit to reduce their speed through this restrictive area. Strike one.

The Gallery passage is the other problem area. Divers have a choice: Either ride the ceiling, or ride the floor. If a diver rides the ceiling, he/she must descend to the bottom (another 15-20ft) to exit into the Eye/retrieve deco bottles. I personally feel that riding the ceiling is a poor choice. While a dive might be 'off gassing' across this shallow section, bubble formation is probably occurring. The drop down to the Eye passage or to retrieve deco bottles will temporarily compress those bubbles which would allow them to bypass the body's most efficient bubble filter: the alveolar capillary bed in the lungs. Strike two.

Another potential issue is the amount of exertion required for entering the cave. While techniques can be employed to reduce this effort (reading the cave, using eddy and staying out of the flow, strategic pull and glide, streamlined equipment), lets face it, this isn't a no flow cave. Exertion may result in increased inert gas loading. Couple this with the factors I listed above, and we have a recipe for DCI. Strike three.

Divers are often in a rush to get on the 20ft bottle. A slower ascent with stops between the Cornflakes and the Keyhole, plus the usual at 50ft, 40ft, and 30ft could make a marked difference in DCI incidents (both clinical and sub clinical). A slow (6 minute minimum) ascent on oxygen from 20ft to the surface is also cheap insurance.

While a diver might be reasonably hydrated at the beginning of the dive, thick undergarments needed to manage long exposures and deco times can contribute to overheating and subsequent sweating and increased fluid loss in the beginning portion of the dive. Divers with long dive times should consider some form of in-water hydration. Some divers are having success with deco or stage mounted camelbaks with either water or a sports drink such as Gatorade or PowerAde.

I understand that the plural of anecdote is not data, but we have limited resources to draw from. I hope that this makes you consider your profile and resulting decompression.

To make some concluding remarks, excellent hydration, nutrition, fitness, and a smooth ascent using all the available research as a guide is the secret. We have to use all the tools available to us to stay safe and not get injured. While the only sure-fire way to prevent DCI is to not dive, if we stay current and constantly evaluate our practices, we can only hope to remain as safe as possible.

[Jay]

Good points. Those are critical areas hen exiting.

Some things I do personally that addresses those areas somewhat:

I go very slowly through the corn flakes and ascend much slower through there then most people I observe. I also prefer to go far left (or far right entering the area) through the big empty room (avoiding the keyhole) with the more gradual sand slope, again slowly.

I usually end up with 50 and 30 foot stops on my VR3, so I have become accustomed to doing those stops in the gallery whether the computer tells me to or not.

I also exit the ear very slowly. The strict cave conservationists can cover their ears or eyes, but I will jam myself in the bottom of the opening and do my ascent to 10 feet at a rate comfortable to me. I much prefer exiting the eye as I have more areas to stop and wait in. Being SM, I am out of the way.

[Serota]

It seems that there have been quite a few people getting bent (to some degree) at Ginnie. I have heard of at least 6 people, and I personally know a few of them. What is so special about Ginnie that causes this high number of incidents?

Maybe it's just that a lot more people dive at Ginnie so that it seems like a lot more than other sites. It would be interesting to know if, for example, the percentage of people getting bent at Ginnie is different than a somewhat similar site like Little River.

[aainslie]

A condescendingly phrased but reasonable set of conjectures. Thanks for the lesson, dad. You may be shocked to know that a huge chunk of us unwashed knew this already. BTW there are, strictly speaking, an infinite set of exit paths, with scraping the top or bottom merely the outer bounds of that set of paths.

I also agree that the large N on the denominator may actually make the proportion of dives that result in DCS comparable with other sites.

[PfcAJ]

Umm...I wasnt trying to be condecending at all. My only hope was that people who hadn't considered all this (newer divers, people that do not frequent Florida, or just people looking to learn something) might get a benefit of having this information in one place. I sure wish I had all this at my fingertips when I started diving. If it doesn't apply to you, then thats just fine, you aren't my target audience.

Sorry if I offended you, Andrew.

[aainslie]

Damn. My attempt at humour goes down in flames again...

It IS useful info. But it did come across as a little condescending.

Since we're into "how to deco at Ginnie" stories, I'll give a couple of my hints:

1) There is absolutely no need to be dehydrated at Ginnie. I drink often and copiously from the cave. No need to bring complicated hydratin packs. Just don't do what my buddy Terry did and drink from the river run. He was leaking at both ends for about 2 days afterwards.

2) Bring entertainment. It's expensive but worth it. I love my ipod touch and its container - nothing like catching up on your TV while on deco. Alternativey bring an ADD buddy. You can get endless entertainment from watching them bounce around trying to find stuff to do. Stops at 50 ft in the eye lights out are a blast on busy days - I swear people think you're a corpse when they spot you staring at them motionless.

3) Run along the ceiling going in AND out wherever you can. It always amazes me how people stick to the ceiling on the way in until they hit the keyhole - and thereafter they're always 3 feet off the gold line. Makes no sense. But bring a helmet - for some reason, I'm always convinced that my head is 3 inches shorter than it really is. Ironically, this is exactly opposite to a similar problem that I have with women.

...and now I suppoes I've hit the condescending club too!

[PfcAJ]

Its all good. I wanted to kick you though, till I read your reply.

Old douchey grandpa Ainsle strikes again.

[fixxervi6]

Working like crazy going into flow increases gas loading over lazily scootering or just pissin about taking your time in low/no flow.

I don't know about other people but when I dive ginnie its cardio workout, and I pad my last stop quite a bit due to this.

[aainslie]

Its all good. I wanted to kick you though, till I read your reply.

Old douchey grandpa Ainsle strikes again.

I'll remind you that it's others that adorn me with these descriptions. personally i think of myself as young, good humoured, and puzzlingly lacking in female attention given my good looks.

[DogDiver]

A few years ago, little river was "the most bent" dive site. The chimney and the stairs afterward were bending many divers. Just food for thought.