One of the most common questions I get from my students is what the progression of courses should be. There are a couple of ways to answer this question depending on where in training someone is and what type of diving someone is most interested in doing. Let’s split this up into a couple of categories and approach it from each perspective. We’ll look at this from the perspectives of both the open water diver and the overhead diver that are interested in doing some decompression dives.

If an open water diver is interested in pursuing decompression diving but has no real desire to do overhead dives, then the answer may seem obvious. It’s just a matter of signing up for an Advanced Nitrox/Decompression Procedures (AN/DP) course and going from there. This isn’t necessarily the best way to approach it, though. I’m not an advocate of deep air diving. While AN/DP certifies divers to dive to depths of 140 or 150 feet deep (agency dependent), I don’t think this is a good idea in most situations. One of the things I like to do with my students is find out where their personal helium depth begins.

Narcosis is pretty much immediate as soon as we begin our descent. We are affected by the nitrogen even at 20 feet deep. However, the effect is so minimal we don’t usually notice it and it won’t affect our ability to respond to issues that may arise. This usually doesn’t occur until people hit the 60-80 foot depth range. But even at this depth, most divers will insist they are not feeling the effects of narcosis. While, I don’t feel it’s necessary for a majority of divers to dive trimix at 60-80 feet, I do believe that divers need to recognize they are affected at that depth, even if only slightly. The need to begin using helium in breathing gas usually doesn’t start until about 100 feet deep. This number varies with different divers, but most will find that anything deeper than 110-120 has a significant effect on reaction time. It can be pretty easy to find that personal helium depth during a supervised dive and some simple exercises.

If a diver is interested in extending bottom time but remaining relatively shallow (Read: below their personal helium level), then AN/DP is an appropriate course. My AN/DP course trains divers how to plan and conduct dives in the 100-120 foot depth range beyond no decompression limits (NDL) with the appropriate amount of standard and accelerated decompression stops. We focus primarily on learning about the various decompression models available out there and how to implement them into our dive planning. We then go out and do some dives.

If a diver is interested in doing deeper dives, though, then there’s a better way to approach this. I offer a course called Advanced Recreational Trimix (ART). This course trains and certifies divers to a depth of 160 feet with minimal decompression. I offer it in conjunction with Decompression Procedures (ART/DP). It’s very similar to the AN/DP course with the major difference being additional discussion time about helium as a breathing gas as well as how it affects our decompression. We also conduct deeper dives utilizing helium in our gas mix. AN/DP is not a prerequisite for ART/DP. A diver can sign up directly for ART/DP without any decompression training or experience.

To summarize, if you want to do longer dives in the 100′ depth range, AN/DP is the course for you. If you want to do deeper dives, then you should consider ART/DP. Knowing the type of diving you want to do will be helpful in making this decision, but if you’re not sure, then save yourself some money and time by taking ART/DP.

Now, let’s look at this from the overhead or cave diving perspective. The same discussion applies to the cave diver in regards to longer dives vs. deeper dives. The difference for cave divers is when to sign up for an AN/DP or ART/DP course. My advice has always been to do this mid-way between the cave training. Complete the Cavern and Intro/Basic Cave diver courses, get some experience diving caves, and sign up for a decompression course. This allows us to complete the training in caves as long as we still adhere to the gas management rules of the Intro/Basic Cave diver.

So why not wait until after completing cave diving training? While agencies don’t typically require AN/DP before completing the final cave diving course, not having AN/DP will limit what can be done during training. A cave diving course is there to teach divers how to cave dive. Learning how to conduct decompression dives should be left to the decompression diving courses. Some cave instructors won’t even accept students into a cave diving course unless they’ve completed AN/DP first. I don’t currently do that, but it’s been something I’ve considered.

I haven’t taught anyone at the cave diving level that didn’t first complete the AN/DP course, but not having AN/DP would make it necessary to spend a few extra hours discussing decompression theory and how it affects us on the longer dives. It also means we may end up turning dives on time rather than gas pressure in order to minimize our decompression obligation. One of the agencies I teach through also allows me to incorporate the use of stage cylinders during the cave course with students who have completed AN/DP or ART/DP.

So, in summary, the progression of training for cave divers I recommend is 1. Cavern, 2. Intro/Basic Cave, 3. AN/DP or ART/DP, and 4. Cave. This progression allows students to get the full benefit of each course and allows us to conduct a majority of the training in caves. We can also do a mix of open water and cave during the AN/DP or ART/DP courses if the student desires.

Having just finished teaching an Intro to Tech course over the past couple of days and having another one scheduled at the end of the coming week, it seems appropriate to write about it a little. What’s interesting about this course is the way different instructors perceive the course.

One of my students posted a question about it on one of the Internet forums and got a variety of responses from instructors and students. One instructor approaches the Intro to Tech course as a very basic course. He states he introduces his students to the different technical gear available, gives them an opportunity to try the gear, and completes the basic in water skills required by standards. While this fully meets the agency standards for the course, it’s not what I really see the course as being. However, I do see the potential for there being an increase in the number of divers that sign up for a course like this because it meets the requirements for taking the HOG regulator service technician course (more on this later).

I take a different approach to the Intro to Tech course. I see it as more of a technical fundamentals course than and introductory course. While I do spend time with my students looking over the different gear options available, that’s a very small portion of the course. Most of our classroom time is spent talking about proper gas management, dissimilar cylinder volume matching, Respiratory Minute Volume (RMV) calculation, dive planning, and emergency procedures. Once we get in the water, in addition to the standard skills required like propulsion techniques, out of air drills, mask removal, and surface marker deployment, we also get the information required to calculate RMV, work on establishing muscle memory, task load in midwater, and more. I incorporate the skills I’d like to see my students come into an Advanced Nitrox/Decompression Procedures (AN/DP) course or Cavern course with so we can focus on more advanced skills during the two to three days spent in those courses. I also shoot a lot of video during the course so my students not only get the benefit of feedback on how they are doing on the skills, they also get to see what they are doing. It’s one thing to be told you keep fanning your free hand, but a different thing to see yourself constantly doing it on video. Video really makes it hit home.

So the point of this is to not blow off a course because of what you may have heard about it or may think of it. Many of the agencies, especially the technical diving agencies, allow their instructors to add more content to their courses. Ask around and interview different instructors. Ask for specific information about the skills that are done during the course. What may not seem like a good course from one instructor may be a great course from another instructor.

Oh, and as for the HOG regulator service technician course. There is a prerequisite for some type of technical diving certification to get into this course and the Intro to Tech course does meet that requirement. E-mail me at chipoladivers@gmail.com if you want more information.

It’s been a while since I’ve posted a new entry. Fortunately, it’s because I’ve been diving a lot! Still diving quite a bit, but thought I’d get back here to post a quick note. The subject of this entry is the importance of overhead training.

The recent alleged death of a diver in the cave located at Vortex Spring brings this subject up. The diver had no previous overhead or decompression training, yet he had supposedly made several dives in the Vortex cave. There is videographic evidence of at least one dive he made there, so he was entering the overhead. The presence of several cylinders in the system also indicates he was probably doing decompression dives there.

Let’s take a look at the type of cave Vortex is. The cavern zone at Vortex is not very large. Fifty feet into the passage and natural day light is no longer visible. However, several open water divers make the trek back to the gated grate located about 300′ into the passage. While this isn’t encouraged by Vortex management, the dredging pipe located in the passage, along with the holiday type lights that lead back to the Piano Room (the room where the grate is located) makes this cave somewhat inviting. Once past the grate, the passage narrows significantly and the ceiling drops closer to the floor. While the first 1000′ or so is passable in backmount, there are a couple of sections where passage in backmount cannot be made without having contact with the cave. The average depth in from the gate through the backmountable passage is in the 110-120′ range. At the point the passage becomes unpassable in backmount, it also drops down into the 150-160′ range. At this point, one must be in sidemount. About 1400′ into the cave is a tight restriction that makes passage without contacting the cave impossible. Exiting from this point is usually in low to zero visibility. This is definitely an advanced cave dive that requires trimix and significant experience.

Cave diving is a very safe activity IF the proper training has been completed and the five guidelines of accident analysis (proper training, continuous guideline, air management, appropriate gas mix for the depth, and good equipment that is well maintained) are followed. Violating any of these guidelines increases the risks significantly, the greatest risk coming with the guidelines in the beginning of this list. Not having the proper training is the number one reason for deaths in caves.

Cave diving training is intensive, requires the appropriate gear, and a great amount of dedication. It’s not something someone can learn by reading about it in books or on the Internet. Of the approximately 600 documented deaths that have occurred in caves since we started keeping track of them about 40 years ago, a majority of those deaths occurred due to lack of proper training.

The following four guidelines are all taught in cave diving training, but someone who has not received that training may not be aware of the guidelines and how important they are to preventing incidents from happening. Air management is more than just diving to 1/3s. In fact, diving to 1/3s is the most liberal way to conduct a cave dive and there have been incidents and deaths that resulted even when this guideline was followed. Using the appropriate gas mix for the depth not only requires knowing what mix to use, but also how to follow an appropriate decompression schedule for that mix and the length of the dive. This requires additional training outside of cave diving training. Violating any one of these guidelines is enough to keep someone from leaving a cave alive. Violating more than one, or all of them, is a near guarantee that the outcome will not be good.

Cave diving training and decompression training are expensive and time consuming. The average cost to complete cave diving training is in the $2000-3000 range. This does not include the gear required to conduct these types of dives. Add another $3000-4000 for that. Then don’t forget the decompression training. Depending on the level of training someone decides to pursue, this can range anywhere from $800-3000 just for the training. A cave like Vortex requires about $1500-2000 in training. There are also additional equipment costs. Breathing gas costs will also be about $100 per dive. Yes, this sounds expensive. It is expensive. But it’s worth every penny if it brings you out of the cave alive.

It’s not worth it to take shortcuts and try to do these dives without the training and experience they demand.

Decompression Dive Training Environments – Cave vs. Ocean vs. Inland

While some may think that decompression training is the same regardless of where the dives are conducted, that isn’t the case. It’s true that the theory is much the same. Advanced Nitrox/Decompression Procedures introduces divers to the basic principles of decompression. Basic (Normoxic) Trimix introduces divers to the basic principles of diving while breathing helium. And Advanced Trimix expands on these basic principles and prepares divers to go to deeper depths. There are different decompression models available for use. There are different methods of determining Equivalent Narcosis Depth. The physiology is the same. However, dive planning and execution can be quite varied dependent on where the dives are to take place.

Unless a diver is planning on “flying the computer”, something I don’t subscribe to, conducting decompression dives in a cave environment requires knowledge of the profile of the cave. It’s not as simple as descending to the maximum depth, staying at that depth for a designated period of time, then beginning the ascent with the planned decompression schedule. The hard floor and ceiling of the cave often dictates the dive profile. A direct descent and ascent may not be possible. There may be an extended period of time during the decompression schedule where you must stay at a specified depth because the ceiling prevents you from making an ascent. Sometimes the ceiling may even require you to descend 10-20 ffw after you have already started your decompression schedule! Planning decompression dives in a cave environment requires quite a bit of attention to detail. Respiratory minute volume must be known otherwise you may not even have enough gas to get to your planned destination. Swim pace must be known otherwise you may not get to your planned destination in the time you allotted. It’s not as simple the square profile diving typically done in ocean and inland bodies of open water.

However, in the ocean, there are other considerations that must be accounted for. While planning the dive may not be as involved as for a cave dive, environmental factors must be considered. What are ocean conditions like? Is the surface choppy, making entry into and exit from the water an issue? Is there a current that could blow you off the line and/or the dive site. Will the dive boat tie into the dive site or do a live drop and pick up? The dive can be done as a square profile, which is fairly easy to plan. However, the decompression portion of the dive my require a jon line to hang comfortably off the line, or a surface marker buoy to mark your location as you do a drifting decompression. Also, unlike in cave diving, you must keep your decompression cylinders with you rather than being able to drop them off at the beginning of your dive. While it’s always a good thing to be familiar with respiratory minute volume so that you know if you have enough gas to stay down for your planned time, it may not be necessary to effectively execute the dive. Once you get to your turn pressure, you simply being your ascent. There is no hard ceiling to prevent this. Also, if something goes wrong during the dive causing you to have to abort early, you can simply begin your ascent. In a cave environment, you must make your way back to open water before you can begin your ascent. None of these issues is seen in inland bodies of water.

Inland bodies of water, such as lakes (with the exception of the Great Lakes), quarries, and sink holes, are fairly neutral environments. While there may be entanglement hazards, there are typically no currents, no rough surface conditions, no drifting decompression stops, no hard overheads. Dive planning involves planning for a square profile, heading out to the dive site, and executing the dive. Surface marker buoys will be deployed because all agencies require this skill, but it’s not necessary for the dive, just for the standards. The biggest issue with inland bodies of water is the decreased visibility, which actually makes the instructor’s job much more difficult because it’s not as easy to keep track of all the students. For the student, it’s an easy environment.

So where should decompression dive training take place? While the initial dives should take place in a neutral environment to introduce skills and ensure students are able to perform the skills, final dives during the various courses should be conducted in the environment the student will be doing most or all of their diving once training is completed. If the student will be diving in both cave and ocean environments, then dives should be conducted in both. However, to take a student through this type of training and only conduct the training dives in neutral inland environments is only doing a disservice to them. Remember, training prepares divers to dive in similar conditions as what they experienced during their courses. Therefore, training in a lake or quarry does not prepare a diver to dive in a cave or the ocean. When you prepare to do your decompression dive training, make sure your instructor is going to take you to dive sites that are similar to where you plan on diving. If you have to travel for your training, then do so. Don’t settle for mediocre training in a lake or quarry.

We offer technical dive training from Intro to Tech through Advanced Trimix. Our courses are conducted in caves for cave trained and certified divers and/or on the Oriskany or in South Florida.