Swim throughs - what could possibly go wrong?

[boulderjohn]

It is becoming evident to me that as diving becomes more advanced (risky), opinion about the risks involved varies, even between agencies. That being the case, it is up to the diver to understand the risks and make sensible choices.

Is it safe to cross a street?

Are we talking about a multi-lane freeway, or are we talking about a crosswalk with a traffic light and walk signal? One is near suicide, and the other is very safe. On the other hand, people have been killed crossing with the proper signal in even well controlled crosswalks. All it takes is a drunk driver, or a driver falling asleep at the wheel. Since we know it is possible to be killed in even the most well controlled crosswalk, does it mean we will never cross a street?

The area in front of the hotel I have used several times in Cozumel has an arch about 6-7 feet under water, and even the weakest snorkelers like to take a breath and swim through it. For a brief moment, they are in an overhead environment. Should it be off limits to divers who do not have overhead training?

The problem is we use the term "overhead environment" to cover a wide variety of situations, from the most benign to the most threatening. Yes, it is possible for something to go wrong in a simple swim through such as was described by the OP, just as it is possible to get hit by a drunk while crossing a normally safe intersection. It would not bother me to see an OW diver decide that such a risk is reasonable and go through, as happens hundreds of times a day in Cozumel. It would bother me very much to see the same diver enter the cavern in Twin Cave in Marianna the way the girl who almost died there in 2012 did. They are two very different environments, all under the same umbrella label of "overhead."

That is why I don't like the term. People are warned not to go into overhead environments without proper training, then they go through the ones described in the OP routinely and say, "Hey, overheads are no big deal." The girl mentioned above charged into the pretty safe cavern in Jackson Blue cave the day before she charged into Twin and almost died. They were both caverns. They were both overhead environments. She had shown she could do overhead environments, hadn't she?

I have a draft of an article on my computer that calls for a rating system for overheads so that people can get some assistance in knowing their degree of difficulty. It is similar to the system used to define the difficulty of ski slopes and rock climbing routes. I have had it for about a year. I haven't had the courage to publish it because I haven't quite worked up the courage to endure the flames that will follow.

 

[Foxfish]

What scares me is the phenomenon of creep . . . where you decide this place looks a little smaller than the last one, but it's probably okay; or you fail to realize the sediment at the bottom of this cavern isn't the coarse sand you're used to.

Complacency and 'creep' is a cause for concern. The other concern I highlighted previously is the 'know it all' diver who thinks that because they have certificates and a few specialized skills they're invincible.

To me the fix in both cases is to carefully investigate the risks and then work out how to limit those risks. Asking questions like:

- Where am I going to dive and what are the conditions?
- What are the real and significant risks?
- Can I reduce the risks to an acceptable level?
- What knowledge and skill sets are required?
- Am I competent to be able to do the dive safely?

Thinking through those questions should make the your diving limits more clear and reduce 'creep' and complacency.

It should make you think realistically about your diving ability. You may have cave diver qualifications but if you've had no experience with the ocean conditions I've described you are inadequately prepared. The qualifications could give a false sense of security and make you more vulnerable.

If you're new to an area, it would involve finding local divers you can trust, talking to them and if possible diving with them to learn about the local environment and it's dangers.

The reason this thread keeps going is that there are a lot of people who read ScubaBoard, and a lot of them are relatively new divers or people without advanced training. They are reading you as saying that you don't need special training to go into overhead environments. They may or may not remember the entire list of VERY restrictive criteria you posited for making that statement.

I did say previously to assume the person entering the cavern had overhead training if that made you feel easier with the discussion.

As far as I'm aware, the nearest freshwater cave people dive is thousands of kilometres away. If I did cavern training here I'd be doing it in a dam ie. an area with no overhead, no current and no surge. I spoke to an instructor with technical diving qualifications and his comment was that the training is not necessary or appropriate for diving caverns in our area. The idea that I'd do this and then progress to cave training to dive the areas I've described is ludicrous. A wreck diving course would probably be the most realistic option. I spoke to another diver who had done that course and he said it was pretty much a waste of time. I would expect that few divers in our area who dive these caverns regularly and with whom I dive would have any formal overhead certification. I've never heard of an accident or death in these caverns even though many divers go well outside the guidelines I've previously suggested.

A lot of the arguments on the forum are because of the different environments in which we dive. Each comes with its own unwritten set of assumptions. I accept the guidelines I provided may not be appropriate to your area. Equally, responses based on your local conditions are not appropriate for the conditions I've outlined.

I'm asking people to put themselves in my shoes. Assume the conditions I've mentioned. I'm asking for a more thoughtful assessment of the risks than the usual "it's overhead, you have to do cave diver training" which may be entirely appropriate in your context. If nothing else, it gives an opportunity to demonstrate why a person here should take "cave diver training".

---------- Post added February 6th, 2014 at 05:06 PM ----------

With a bit of practice you can swim inches above silt without disturbing any of it.

Only a cave diver would say that. There is almost always some surge in our caverns and if it was silty you'd want to stay well off the ocean bed.

 

[boulderjohn]

As far as I'm aware, the nearest freshwater cave people dive is thousands of kilometres away. If I did cavern training here I'd be doing it in a dam ie. an area with no overhead, no current and no surge. I spoke to an instructor with technical diving qualifications and his comment was that the training is not necessary or appropriate for diving caverns in our area. The idea that I'd do this and then progress to cave training to dive the areas I've described is ludicrous. A wreck diving course would probably be the most realistic option. I spoke to another diver who had done that course and he said it was pretty much a waste of time. I would expect that few divers in our area who dive these caverns regularly and with whom I dive would have any formal overhead certification. I've never heard of an accident or death in these caverns even though many divers go well outside the guidelines I've previously suggested.

My situation is similar to yours. Not many years ago I assumed I would never have any cave training because of the combination of my age and the fact that there were no caves near me. I started doing technical training, and I did that for a few years, again with no thought of cave diving. I learned to use doubles, control my buoyancy, use non-silting kicks, etc. After a while I realized I had learned a large percentage of what is needed for cave training, which would mean I could get through cave training much faster than normal.

So I traveled about 2,000 miles to begin my training, and I learned that those years of technical training were indeed valuable. I got pretty far through the course sequence. I waited a while, practicing the specific cave skills I had been taught in open water and even a pool. I then took another 2,000 mile trip where I got more cave experience. Finally, I went back and finished up.

You can indeed do a whole lot of the training locally and then make the big trip to the caves when you have those basic skills mastered. In fact, it is what I recommend for everyone. Don't pay a cave instructor to teach you the skills you can learn in open water. Go to the cave instructor only after you have those things down.

In the last year or two, I have planned my vacations around the availability of caves, and cave dives have been a very large percentage of my logged dives.

 

[Glenlivet]

Only a cave diver would say that. There is almost always some surge in our caverns and if it was silty you'd want to stay well off the ocean bed.

Has this surge a vertical component?

By the way: I have no cave training, I'm just diving in horizontal trim with non-silting propulsion, regardless of the dive site. Never been to one where this was not preferable.

 

[tursiops]

Has this surge a vertical component?

It doesn't need a vertical component if it is a real fluid with viscosity and turbulence. It will stir up the silt (or find sand) it flows over unless it is very very slow.....and typically surge isn't very very slow.

 

[Foxfish]

That is why I don't like the term. People are warned not to go into overhead environments without proper training, then they go through the ones described in the OP routinely and say, "Hey, overheads are no big deal." The girl mentioned above charged into the pretty safe cavern in Jackson Blue cave the day before she charged into Twin and almost died. They were both caverns. They were both overhead environments. She had shown she could do overhead environments, hadn't she?

I have a draft of an article on my computer that calls for a rating system for overheads so that people can get some assistance in knowing their degree of difficulty. It is similar to the system used to define the difficulty of ski slopes and rock climbing routes. I have had it for about a year. I haven't had the courage to publish it because I haven't quite worked up the courage to endure the flames that will follow.

I can see a rating system being useful in popular areas. Over here we have relatively few divers and there are literally thousands of these swim throughs and caverns.

I'd also like to see divers trained to take be more proactive in thinking about their safety. The simple guidelines I mentioned previously are one approach.

---------- Post added February 6th, 2014 at 06:01 PM ----------

You can indeed do a whole lot of the training locally and then make the big trip to the caves when you have those basic skills mastered. In fact, it is what I recommend for everyone. Don't pay a cave instructor to teach you the skills you can learn in open water. Go to the cave instructor only after you have those things down.

In the last year or two, I have planned my vacations around the availability of caves, and cave dives have been a very large percentage of my logged dives.

From what I could gather, there are some local divers who follow a similar path to the one you describe John. There are agencies that offer the cavern and cave diving courses, do some of the training here it seems and then travel over to the caves. Frankly I don't have the slightest interest in cave diving. It sounds too risky!

---------- Post added February 6th, 2014 at 06:03 PM ----------

It doesn't need a vertical component if it is a real fluid with viscosity and turbulence. It will stir up the silt (or find sand) it flows over unless it is very very slow.....and typically surge isn't very very slow.

And the surge rocks you around so it is easy for a fin to dip and hit the bottom.

 

[fbk]

So far I think I am the only one who's replied who lives here and dives these "caverns". Foxfish I am not sure what your point is other than to try to justify not needing overhead training to enter all overhead environments including ones like these. I don't disagree with you, however I can see how it seems a bit trollish towards cave divers who dive in say Florida or Mexico who, for their environments, are entitled to condemn someone flutter kicking their way through a cavern with no overhead training. I have full cave btw but it is irrelevant to this discussion.

Using the "crossing the street" analogy, as far as overhead environments go they are a crosswalk, with boom gates, on a single lane road, in a country town, on a Sunday. That doesn't mean things can't still go wrong. It also doesn't mean you need redundant gear, guidelines, backup lights, gas planning etc to enter them. Silting is a complete non-issue. You could leave your fins behind and dig your hands in the sand for propulsion and not silt out. They are basically parts of the reef that are hollow underneath, or have formed in a way to create a space between bits of reef. Surge is pretty much constant and the finest sand you will find is busted up shells. Some are tighter or deeper or darker than others, obviously the risk increases with each.

It's said that the only real emergency in a cave is running out of air. The same applies here, if it happens when you don't have a direct ascent to the surface. I've been briefly deprived of air in a small, shallow swimthrough and it wasn't fun. Having all the gas in the world on my back, a dive plan, 4 lights 3 reels and 2 cutting devices wouldn't have made one bit of difference. The one thing I guess that would (which I did switch to long before any cave training taught me to) was to wear a backup reg around my neck for easy access, and a longer primary hose. I would not dive any other way now. Before anyone asks, I was with buddies who had already gone through.. when I didn't appear as expected they went to see what was wrong, it probably would have been too late if I hadn't already managed to get my reg back.

All that said, cave training was the best and most rewarding diving I have ever done.. even if it's not required to swim through holes in the reef at Rotto.

 

[BRT]

It's even possible to do them in splits :shocked2:

But you will die.

 

[Foxfish]

So far I think I am the only one who's replied who lives here and dives these "caverns". Foxfish I am not sure what your point is other than to try to justify not needing overhead training to enter all overhead environments including ones like these. I don't disagree with you, however I can see how it seems a bit trollish towards cave divers who dive in say Florida or Mexico who, for their environments, are entitled to condemn someone flutter kicking their way through a cavern with no overhead training. I have full cave btw but it is irrelevant to this discussion.

The point of the thread was to discuss the risks associated with diving overhead in the conditions I've outlined. I was interested to hear what other risks would surface in the discussion. It is probably safe to say we've identified the important ones.

Then there is the more general consideration of diver training. In theory OW divers are not supposed to dive in an overhead environment. Which begs the question what training should an OW diver do to prepare them for diving in our offshore caverns? The obvious choice would be a 'cavern' course. As far as I'm aware no one offers such a course which suggests to me there is neither the market nor the need for it. If we had a number of injuries and deaths of people diving these caverns I'd guess that would not be the case.

My experience is that most people don't give it a second thought. I dive these caverns regularly with charters and there has never once been a suggestion that divers need anything other than an OW certificate. At the same time I do accept there are additional risks associated with these dives, especially for divers prone to panic, and see the merit of thinking through the risks. Hence the thread.

Using the "crossing the street" analogy, as far as overhead environments go they are a crosswalk, with boom gates, on a single lane road, in a country town, on a Sunday. That doesn't mean things can't still go wrong. It also doesn't mean you need redundant gear, guidelines, backup lights, gas planning etc to enter them. Silting is a complete non-issue. You could leave your fins behind and dig your hands in the sand for propulsion and not silt out. They are basically parts of the reef that are hollow underneath, or have formed in a way to create a space between bits of reef. Surge is pretty much constant and the finest sand you will find is busted up shells. Some are tighter or deeper or darker than others, obviously the risk increases with each.

I can only hope your comments will be enough to put the matter to rest. Thanks. You do get a bit of silting in the sounds around Rockingham (Cockburn and Warbro) but there are few reefs in those areas. I did my OW course at the Rockingham Wreck Trail and visibility got down to about 1 m. I don't think I've seen it much worse than that since.:blinking: The lower levels of the Saxon Ranger in Warnbro Sound quickly silt out with careless finning. Agree silting is generally not an issue off Rottnest. I haven't done much diving off the north suburban beaches. I lost a good friend in a diving accident near Hillaries. Details are sketchy but I heard it was in a little cave just offshore. That was before I started diving.

General visibility can get very poor during and just after storms but if that is the case I don't dive. It gets back awareness of the weather and ocean conditions which tourists typically lack. It's a little funny to go out on the charter boat the weekend after a storm and hear people recount stories of the previous weeks terrible conditions. One peep at the weather conditions was all the convincing I needed to stay at home.

It's said that the only real emergency in a cave is running out of air. The same applies here, if it happens when you don't have a direct ascent to the surface. I've been briefly deprived of air in a small, shallow swimthrough and it wasn't fun. Having all the gas in the world on my back, a dive plan, 4 lights 3 reels and 2 cutting devices wouldn't have made one bit of difference. The one thing I guess that would (which I did switch to long before any cave training taught me to) was to wear a backup reg around my neck for easy access, and a longer primary hose. I would not dive any other way now. Before anyone asks, I was with buddies who had already gone through.. when I didn't appear as expected they went to see what was wrong, it probably would have been too late if I hadn't already managed to get my reg back.

I've heard similar stories mostly from people squeezing into tight restrictions.

All that said, cave training was the best and most rewarding diving I have ever done.. even if it's not required to swim through holes in the reef at Rotto.

Where did you do the course? What parts did you find particularly useful?

 

[gcarter]

The point of the thread was to discuss the risks associated with diving overhead in the conditions I've outlined. I was interested to hear what other risks would surface in the discussion. It is probably safe to say we've identified the important ones.

Then there is the more general consideration of diver training. In theory OW divers are not supposed to dive in an overhead environment. Which begs the question what training should an OW diver do to prepare them for diving in our offshore caverns? The obvious choice would be a 'cavern' course. As far as I'm aware no one offers such a course which suggests to me there is neither the market nor the need for it. If we had a number of injuries and deaths of people diving these caverns I'd guess that would not be the case.

My experience is that most people don't give it a second thought. I dive these caverns regularly with charters and there has never once been a suggestion that divers need anything other than an OW certificate. At the same time I do accept there are additional risks associated with these dives, especially for divers prone to panic, and see the merit of thinking through the risks. Hence the thread.



I can only hope your comments will be enough to put the matter to rest. Thanks. You do get a bit of silting in the sounds around Rockingham (Cockburn and Warbro) but there are few reefs in those areas. I did my OW course at the Rockingham Wreck Trail and visibility got down to about 1 m. I don't think I've seen it much worse than that since.:blinking: The lower levels of the Saxon Ranger in Warnbro Sound quickly silt out with careless finning. Agree silting is generally not an issue off Rottnest. I haven't done much diving off the north suburban beaches. I lost a good friend in a diving accident near Hillaries. Details are sketchy but I heard it was in a little cave just offshore. That was before I started diving.

General visibility can get very poor during and just after storms but if that is the case I don't dive. It gets back awareness of the weather and ocean conditions which tourists typically lack. It's a little funny to go out on the charter boat the weekend after a storm and hear people recount stories of the previous weeks terrible conditions. One peep at the weather conditions was all the convincing I needed to stay at home.



I've heard similar stories mostly from people squeezing into tight restrictions.



Where did you do the course? What parts did you find particularly useful?

Are you sure about that?

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