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.

Make sure you visit Chipola Divers and check out the Decompression Dive courses we offer. Our courses are conducted in caves for cave trained and certified divers and/or on the Oriskany or in South Florida.

Oriskany diving off the M/V Spree with Joel of TDL

I’ve wanted to dive the Oriskany since it was put to its final resting place in May 2006. Even after living in the Florida panhandle for 3.5 years, I still hadn’t made it out there. There were a couple of reasons for that. First, not many charters will cater to divers who want to do decompression dives on the Oriskany and allow them to do the diving they want to do. Second, spending a couple of hours on a small boat to travel the 20+ miles off shore, followed by another couple of hours to get back to shore isn’t appealing, especially when only one decompression dive is allowed.

A few months ago I came across information about a liveaboard experience out on the Oriskany. The trip involved heading to the wreck, tying onto it, and staying put for 3 days of diving. And to make it even better, it was a trip catering to decompression diving. Joel Silverstein, Tech Diving Limited, was the trip organizer, and knowing about his previous trips, I knew this would be a great trip. After a couple of e-mails with some questions I had about the trip, I was booked.

October 6^th arrived and I was packed and ready to go. I left for Pensacola in the afternoon, arriving at Joe Patti’s around 5pm. Several divers were already there and loaded. I loaded about 500 lbs of gear onto the M/V Spree, the boat we would be living on for the next 3 days and 3 nights. If I could have driven my van onto the sun deck, I would have!

Here’s one of the nice things about the Spree. It can sleep 24 people in the main passenger cabin, but since we were a technical charter, there were only 12 divers on the trip. We had more tanks and more gear and needed more space, and we are willing to pay for that extra space. We had plenty of room for everything we brought with us. The Spree also has banks of air, nitrox, oxygen, and trimix. She also has a booster onboard so O2 cylinders could be topped off properly.

Once settled in, we headed into the Salon for the boat briefing. Captain Frank Wasson, owner and captain of the M/V Spree, is quite the character. I realize he’s done this briefing hundreds of times, but he still keeps it interesting and funny, using visual aids and more! I won’t reveal any information from the briefing, but let’s just say I had nightmares about the toilets! :D For anyone who’s been on a boat with plumbing, you know there are certain things you need to do to keep them functioning…especially with 12 divers who are consuming every last bite of food on board!

After the briefing, we hung out for a while talking and getting to know each other before turning in for the night. The Spree wasn’t due to leave dock until 4am, which was nice since the tide would be in our favor. We finally headed off to our bunks eagerly anticipating waking up floating over top of the Oriskany.

Most of us were up before 7 and watched the activities on deck as the crew was getting ready to set its mooring line. It went without a hitch. The Spree crew had already set the chain on the flight deck less than 50’ aft of the island on a previous trip and just had to tie in to it. The depth at the chain was about 150 fsw. We had breakfast and prepared to splash by 9am. The night before we had discussed the plans for the trip and decided a maximum of 2 dives each day would be the rule due to the depths we would be going to. Everyone was fine with that. In fact, some days some divers only did 1 dive.

While on this trip, I did 2 dives a day for a total of 6 dives. My maximum depths for those dives ranged from 149 fsw to greater than 200 fsw a couple of times during a visit to the screws and to the bow of the wreck. Most of the dives stayed in the 130-170 fsw depth range. Everyone on the trip came with a buddy and I was going to be diving with Joel most of the trip. Not only was I there to dive the Oriskany, but I was also working on my Advanced Trimix Instructor rating with Joel. Joel has done a lot in the dive industry, and specifically in decompression diving. He’s worked with some of the best minds in the industry and published lots of papers on decompression theory. I couldn’t think of many others I could learn as much or more from. I got a lot of information during the trip and a lot of great files from Joel, some of which I will be incorporating into my own courses.

The first day was used for orientation dives. Most of us dropped down the line and headed over to the island, the only interesting attraction above the flight deck. The island sits just aft of center on the starboard side of the Oriskany. The flight deck is at 150 fsw with the top of the island in the 90 fsw depth range. It may be a little shallower, but during our island dive we swam around it checking out all of the features and didn’t see anything that was much of interested shallower than 90 fsw. A couple of dives on the island and we saw all of the outer parts of it and even did some minor penetrations.

The second day we took the scooters and headed back to the stern to check out the screws. We dropped down to the flight deck, over the starboard side of the wreck to about 180 fsw and scootered along at that depth checking out the various openings to the wreck, including the openings to the hangar deck on both sides. At the stern we dropped down and swam over to one of the screws that was about as big as a Volkswagon Bug! After a few minutes we headed back up to 180 fsw and scootered along the port side of the wreck until we got back to the area of the island and ascended up to the flight deck to cut back across to our mooring line for our ascent. After our decompression, we got back on the Spree to have lunch. Three hours later we splashed again for a shallower dive around the island.

Our third day we planned a penetration into the Hangar deck. We dropped down the mooring line, headed over the starboard side just over one of the Hangar deck entrances and set a line. While the opening to the Hangar deck is pretty large, the visibility wasn’t good enough for us to see light all the way across the deck. We reeled all the way across to the other side and tied off at the top of a ladder that led to a lower deck which is located pretty close to an outer door. The dive was turned on gas and we headed back to the mooring line for our ascent.

The final dive of the trip was scooter time again! After gearing up and splashing, I hit the trigger and dropped to the flight deck in about a minute. Once at the flight deck, I checked my watch and kicked the speed up to speed 3 on my SS Magnus. I headed to the bow about 10’ off the starboard side of the flight deck, dropping down at the bow to check it out for about a minute, then back up to the flight deck continuing back along the port side, rounding the stern and back to the starboard side until I reached the mooring line again. The Oriskany is 911’ long and about 150’ wide. Add some additional distance to make up for staying about 10’ off the edge and that puts this trip at over 2200’, which I was able to complete in less than 10 minutes, including the time spent checking out the bow. And, the current had kicked up to probably its worse the entire trip! Once returning to the mooring line, I headed over to the island and scootered around it a few times to see if I missed anything on my previous dives. I still had time to pass until my planned ascent, so I scootered along the flight deck, zig zagging all over the place until I got bored and decided to head back up.

During all the dives, bottom temperature was 68 degrees (just my temp!) with visibility ranging from 30’ to about 90’ at its best. The best conditions we had happened on the first day. There was a significant thermocline at 110 fsw dropping the temperature from 79 degrees to about 70, followed by another slight thermocline at about 130 fsw. The current was fairly significant the first dive of the trip and almost nonexistent the second dive of day 1. It then kicked back up days 2 and 3, being the worse the afternoon of day 3. It was going starboard to port the entire time.

We couldn’t have planned for better weather. It was sunny and in the 80s the entire time we were there. Capt. Frank likes to keep the inside of the Spree fairly cool. Some of us were wearing sweatshirts when inside! The seas were less than 3’ the entire time. And we got all of the dives we wanted! The service on the Spree is top notch! Capt. Frank and his wife, Mel, run a great ship and service. The food was great, and the chefs were able to accommodate my request for vegetarian food. Everyone on the crew was courteous, friendly, and helpful.

The Oriskany is definitely a great dive site for divers able to go beyond recreational depths and spend some time at depth. While there are some things to see on the island, its depth doesn’t allow for much bottom time for divers unable to stay beyond no decompression limits. It’s definitely better suited to divers able to plan and execute decompression dives. It’s somewhere I would definitely like to use to train students in Advanced Nitrox/Decompression Procedures and Trimix if I can find a charter willing to work with the schedule I need. In the meantime, I know the Spree will be heading back there for more extended trips and I plan on taking advantage of that.

All in all, it was a great 3 days of diving with a great group of people. I got to meet some people I have only known through the Internet and spend some time learning from Joel, who I’ve known for several years now. This was my first “technical” liveaboard, but will definitely not be my last.

Oh, one more thing, I finally got to do my first sidemount dives off a boat. Here’s my assessment – it’s so much easier than backmount! At least on the Spree, it was. The benches are tall enough on the Spree that I was able to clip my cylinders on while the bottom of the cylinders rested on the bench. Once my sidemount cylinders and decompression cylinders were all clipped on I made my way to the starboard side to splash. I quickly put my fins on and did a giant stride off the side of the Spree. At the end of the dive, getting out of the boat was also not a problem. The first day, I did my dives in backmounted 95s and had a difficult time climbing the ladder back onto the Spree. Climbing the ladder was much easier in sidemounted 108s, even though they are heavier. The location of the weight makes a huge difference in how it feels on your knees and ankles coming up those ladders and on your center of gravity. With sidemounted cylinders, you are being pulled down, not backwards. Granted, we were only in 2-3’ seas, but it was definitely easier for me. Unless I’m teaching divers in backmount, I will definitely dive sidemount off dive boats!

Don't forget to visit our website - Chipola Divers!

Choosing a Sidemount Rig

"What sidemount system should I buy?"

This is one of the most common questions we hear from our students. While it appears to be a simple question at first glance, it's not quite that easy to answer. In fact, our initial response is always, "What type of diving do you plan on doing in sidemount?" No single system on the market, or even homemade, is perfect for every type of diving. The first thing a diver considering purchasing a sidemount system needs to do is consider the type of cylinders that will be used with the system.

At this time there are several commercial systems available to divers. However, not all systems are equal. While most can easily accommodate heavier steel cylinders, there are some that cannot. Our experience has been that anything less than a wing with 50 pounds of lift isn't very suitable for larger steel cylinders or smaller steel cylinders with stage cylinders, especially for divers who only dive wet. While there are modifications that can be done to counteract the extra weight of steel cylinders, they tend to add more bulk and complication to the system. There are enough commercial systems available with 50 pounds of lift or more that purchasing a system with less lift or one that requires the addition of an air bladder doesn't make much sense.

If a diver is planning on primarily diving aluminum cylinders, then the commercial lower lift systems or simple harness systems with an air bladder as an addition will work fine. Divers may also consider building their own sidemount system. These systems are simple enough, and with the minimal amount of lift needed, allow for a wide variety of choice for air bladders. While building a system can be done by most anyone, building a good system requires some knowledge of sidemount diving or conferring with an experienced sidemount diver.

Trying to make a sidemount system with 50 pounds of lift or more can be a little more challenging. Using one of the current commercial air bladders available can help simplify this process. However, if a diver wishes to build a system using a different air bladder, this will likely involve some modifications such as sewing additional material onto the outer fabric.

Once the type of cylinder is determined, the next question a diver needs to ask is what type of diving will be done in sidemount. There are several reasons to dive sidemount:

• to get into smaller cave passages
• medical issues
• added redundancy of independent cylinders and the ability to see the valves and first stages
• the increased stability of moving the cylinders closer to the center of gravity of the body
• the cool factor

If it's for any of the last four reasons, then there's really no issue as to what system is purchase except for the comfort of the harness. If the reason for diving sidemount is to get into smaller cave passages, then the attributes that must be considered are the profile of the system and the snag factor of the system.

The systems with less lift are, of course, the lowest profile systems available. But with that, divers are giving up the ability to use heavier cylinders. This is fine for some locations, but most of the cave systems in North Florida are in the 60-100' depth range, or more, and smaller cylinders won't allow for much penetration. With heavier cylinders, the profile must be a little higher, but you still want to keep it as low as possible. This is not the case with all of the commercial systems. So, be careful, and compare the profiles when shopping. One particular commercial system appears to be made specifically for the open water market than for cave divers.

Some sidemount systems have incorporated flexible webbing to help retract the air bladder when air is exhausted. While this appears to be a great idea, the webbing does present some issues. We have gotten caught up in the ceiling of very low passages and bedding plains by limestone formations jutting out from the ceiling in a standard system that does not have any webbing on the back. For the purpose of getting through really low passage, having anything on the back of the wing that can catch on formations sticking down from the ceiling can be counterproductive. A clean system without the add-ons appears better suited to this type of diving.

Finally, the comfort of the system needs to be assessed. Standard harness systems with shoulder straps that route to the rear of the system, in our opinion, aren't as comfortable as a harness with shoulder straps that route directly down to the waist strap. Many divers choose to mount backup lights on their shoulder straps. When the shoulder straps route to the rear of the system, it makes it difficult to mount lights in this location because the lights would be positioned under the cylinders making them difficult to deploy, and also uncomfortable because the cylinders would be pressing them into the diver's torso. Having shoulder straps that route directly down to the waist strap also makes the system more stable. With rear routed straps, the waist strap has two attachment points - the rear of the harness. With waist strap routed shoulder straps, the waist strap now attaches at the rear and is further stabilized a few inches apart from the center where the crotch strap attaches creating more stability in the harness.

Keep checking back. Our next post will cover common, and not so common, modifications to commercial sidemount systems.

Make sure you check out our website - Chipola Divers.

Why sidemount?

There's a common misconception by many divers that sidemount divers only go into small spaces. While that is one of the reasons for diving sidemount, it's not the only one. It's also not the most common reason for diving sidemount. Many divers choose to dive sidemount because the advantages of the system appeal to them or because of health related issues. And, yes, some even do it because of the cool factor.

Sidemount was originally created as a way for cavers to get past sumps they encountered in dry caves. The first sidemount rig was very different from the rigs we currently see being commercially produced by dive equipment manufacturers. It consisted of a simple belt with a loop on each side to hold the cylinders on the body of the diver. The tanks were positioned low on the body. The main advantage of this configuration was the simplicity of it. Cave explorers were more easily able to carry single tanks, rather than manifolded tanks, into the caves to the sumps where they would be needed. The harness system was also small enough to either be worn or carried in a small pack.

As cave diving in the UK progressed, cave diving was also experiencing its beginnings in the United States. Florida, well known for the thousands of fresh water springs, was the center of cave diving activity. Quite a bit of cave exploration had taken place in many of the known springs. But the passage that was explored was mainly large passage that could only be negotiated by divers wearing backmounted double tanks. This left miles of passage unexplored. Some divers began experimenting with the harness systems being used in the UK. The need for an air cell for buoyancy control was more of a factor in the Florida systems so divers began modifying jacket BCs for sidemount configurations.

Rather than bore you with more history of sidemount, we'll fast forward to today. In the early 2000s, the first couple of commercially available sidemount systems were produced and placed on the market – the Dive Rite Nomad and the Golem Gear Armadillo. While they shared many similar features, they also differed from each other in many ways, namely in the harness and the lift capacity of the wing. Today, we have over half a dozen commercially produced sidemount systems available to divers. Some of these systems are suited to cave diving, some are better suited to open water diving, and some are marketed for both cave divers and open water divers. While there are many divers who dive these systems unchanged out of the box, many also make modifications to suit their diving to these systems (more on modifications in a later post).

Sidemount systems continue to evolve as more and more divers experiment with it. Unlike traditional backmount systems, there will likely not ever be a standard sidemount configuration. While most divers begin diving manifolded backmounted double tanks for a specific purpose, such as technical diving, as stated earlier, divers begin sidemount diving for different purposes. As long as this holds true, a standard rig will not develop.

One of the original reasons divers started diving sidemount was to get into smaller passages. Not all passages are passable with backmounted cylinders. While the passage may be pretty wide, the floor to ceiling height doesn't allow passage of a backmounted diver. There are several passages located in the caves of North Florida that are only passable by lower profile sidemount divers. There are even several passages and caves that have significant size passages, but the opening to them is only large enough for a low profile sidemount diver. While backmounted divers have tried to pass through these openings, many fail, and the damage they are causing to the system is very evident. In this case, sidemount is using the right tool for the dive.

Some people dive sidemount for health related reasons. Whether it's a bad back or bad knees or ankles, removing 100 pounds of steel from your back can be an orthopedic miracle! Dissenters will argue that this requires more trips to the water and sidemount divers still need to carry tanks, but that's not necessarily the case. With a $40 truck cart from Wal-mart, tanks are easily rolled to the water from your vehicle in one trip. The second trip is one without any heavy tanks, or you can leave your truck cart at the water and get in (well, that is if you're not at Ginnie otherwise the cart might not be there after the dive). Once in the water, the tanks are much lighter and easier to handle. In the water, sidemount is also a lot easier on the diver's back. Moving the tanks to the side gets the weight mass off the spine. Moving the tanks down also allows a different body position in the water. While many backmount divers must arch their backs to maintain a horizontal position in the water, this isn't the case in sidemount.

Finally, there's the cool factor. I'm not going to elaborate on this type of sidemount diver. They are pretty easy to pick out. Fortunately, at least in my experience, there aren't too many of these, not in Jackson County anyway.

Keep checking back here for more on sidemount diving. And don't forget to visit our website - Chipola Divers.

Overhead and decompression training or not...

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.

Don't forget to visit our website - Chipola Divers

The Progression of Training.

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.

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Gear Modifications

I was recently asked a question about why I showed one of my students a modification that isn't normally done in backmount. This question came up as a result of a discussion on one of the Internet forums. Here is a slightly modified ( ;-D ) version of my response:

I received an e-mail asking about the reason I have my inflator and dump valve swapped and why I showed one of my students that modification. As my students has already stated, his intention is to transition to sidemount eventually. One of the common modifications in sidemount rigs is swapping the inflator and dump. There are a few reasons for this. In the standard wing, the butt dump is located on what is the underside of the wing when it is mounted properly. Air rises, so when dumping air from here it is necessary to change from a horizontal position to a head down position so the air bubble can rise to the bottom of the wing and release from the exhaust. This change in position isn't always possible when diving some sidemount passages. Also, with the inflator hose on the top of the wing, the only way to get all of the air out of the wing, short of inverting and using the butt dump, is to go into a head up position and raise the inflator hose up. It's physics. Also, in a sidemount rig if the inflator hose is on top, the elbow is exposed and unprotected and subject to damage.

Okay, so with that aside, I also had a student in the course that was in sidemount configuration. When looking over his rig I spoke with him about the two different ways of configuring the inflator and dump valve. I explained to both students the advantages and disadvantages of both and gave them the option of configuring their rigs either way. One thing I never do in my courses is tell my students how they must configure their gear, unless it's a safety issue! I let them know all the different ways I have seen rigs configured and allow them to make the choice.

One of the more important things about overhead diving, both real and virtual overhead, is to build up muscle memory. It's absolutely necessary that divers know where the inflator is, the dump valve, d-rings, cutting tools, etc. I started my cave and tech instructor internships about a year after having gone to sidemount. I hadn't been in my backmount rig in over a year and one of the issues I found I had was reaching for the inflator and dump without thinking about it. They were both in different locations on my backmount wing and I found myself constantly going to the locations where my sidemount inflator and dump are. I teach students in backmount and sidemount. I also feel it's a disservice to my students if I don't demonstrate skills, such as valve drills, in the configuration they are in. So I dive in backmount when I have students in backmount. Somewhere along the line I decided to mount a set of manifolded doubles to my sidemount rig. This left the inflator and dump in the same locations as I'm used to and reinforced the muscle memory I have built up over the years. I also found that dumping from the top was much easier , even in backmount! Because the dump valve is on the back of the wing (or the top when it's on), there is no need to change orientation in the water. There's no need to go head down or head up. Just reach up and dump. The air, as per the law of physics, exhausts up like it's supposed to. Because my student is intending on eventually diving sidemount (before he takes a cavern course), it also made sense to start building that muscle memory now in his current rig. While the inflator and dump may be in slightly different locations, they will be close enough that the transition should be fairly easy. I presented him with the information and he made the decision. While I see some benefit to some of the DIR philosophies, I don't agree that everything needs to be one way. I believe doing what works for one's own diving is the way it should be, as long as safety is not compromised.

And as for technical v. recreational courses... According to many agencies, cavern and intro/basic cave are recreational, but so are cave and advanced nitrox and decompression procedures. IANTD even considers Advanced Recreational Trimix as a recreational sport diver course (max depth of 160'). The technical courses begin with Technical or Extended Range Diver (max depth of 180') and continue with normoxic trimix and above. While some may disagree, the skills learned in ITT are an excellent foundation for cavern. The cavern diving course involves a lot of task loading. There is a lot of line running and doing multiple skills at the same time. Rather than learning to multitask in an overhead environment, it's beneficial to learn how to maintain neutral buoyancy and horizontal trim while task loading prior to that. This is where ITT comes into play.

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Open Water course

Although a majority of our courses are overhead and technical related - cavern, cave, advanced nitrox, etc - we do teach open water courses on a somewhat regular basis. We've taught a couple of open water courses this year and have another starting this week. What brings up this subject today is a particular discussion on one of the Internet forums.

A particular instructor has posted in an instructors only section of the forum that an open water course with 6 student go by the following schedule - 3 hours classroom, 6 hours pool/confined water, and 8 hour at the quarry. He claims he is able to teach everything that needs to be taught and produce 6 competent divers who have been able to master the 20 skills required of an open water diver. When I stated I give my students about twice the amount of instruction time, he retorted by saying I was too slow and stupid to be able to get the information across faster. I don't feel he deserves a response to that. But I do feel our students, current and prospective, do deserve to know why we teach our courses the way we do.

There is a lot of information to learn in the basic open water course. This is the foundation for all other diving courses. At the completion of this course, my name is going on a diver's card stating I feel that diver has completed all of the requirements necessary to go dive to a depth of 60 feet without my supervision. Our classroom time does take about 5-6 hours. There are 5-6 sections in the open water student manual, depending on the agency. The subjects that are covered are physics, physiology, environment, equipment, dive planning, and many more. Each section also has a quiz which must be reviewed and there is a final exam consisting of 35-50 questions. Finally, we show a couple of videos directly related to the environment we teach and dive in to our students. We believe everything we do in the classroom is absolutely necessary to produce safe divers.

As for the confined water sessions, 6 hours simply is not enough. Each course must start out with a watermanship skills evaluation. Students must swim 200 yards and tread water for 10 minutes. This takes a minimum of 45 minutes to conduct (we let our students rest between skills). We then spend about an hour or two teaching our students how to snorkel and breath hold dive. While a snorkeling course is not a requirement during an open water course, we have found that teaching students how to breathe out of a snorkel, clear their snorkels and masks of water, and equalize their ears during a breath hold dive helps students master the open water scuba diving skills much easier. Once all of this is completed, we begin the confined water sessions. There are 4-5 (agency dependent). We could just teach the skills, have the students repeat them a couple of times and move on. We don't do that, though. After teaching our students the skills, we spend a majority of the time swimming around the basin and drilling the students over and over so they do have the opportunity to master each of the skills. We also feel that by having our students perform the skills midwater while swimming makes them better divers than having them perform them while kneeling on the bottom. I think you can see why this takes 10-12 hours to complete.

Finally, we head out to our open water sites and conduct the four open water dives. We have our students plan the dives, using proper air management rules. We get in the water and we begin our dive. During the dive, while swimming around, we have the students perform the skills they were taught during the confined water sessions. We stay underwater until the student has reached the planned ascent air pressure. This could be over an hour if someone has a good consumption rate. However, many instructors will spend the minimum 20 minutes on a dive with a majority of it kneeling on the bottom in a semi-circle to perform the skills. During our surface intervals, we also talk to our students about other courses they could take after the open water course. We explain all the possibilities to them. We talk about the dangers of cavern and cave diving without the proper training. We talk about the places we've been and the things we've seen. After all, diving is a social activity!

So, you let us know. Which format would you rather have? We're not about to change our format, but if you would rather have the 17 hour course, we know where we can refer you...

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Intro to Tech

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.

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Sidemount

Sidemount seems a good first topic to start off with since it's our primary choice in gear configuration. We began playing around with sidemount a few months before moving to North Florida in 2007 and immediately saw and felt the benefits of diving sidemount over diving backmount. Shortly after moving we took a couple of Dive Rite Nomads for test dives and came back with big grins on our faces and left with less money in our wallets!

At the time the Nomad and the Armadillo were the only two manufactured sidemount systems available. We had researched both and decided to go with the Nomad for a couple of different reasons. The first was the lift. The Nomad ( at that time) had a lift capacity of 50 pounds while the Armadillo's lift capacity was and is only in the mid 30 pound range. Diving the North Florida caves with steel cylinders, more lift seemed like the best decision. Another issue was the lack of availability of the Armadillo. There weren't as many dealers carrying the Armadillo, and at some point (I can't remember whether it was then or sometime later), no one was making or selling the Armadillo. Today it still remains difficult to get one.

Three years later and sidemount systems have flooded the market. We now have several different sidemount rigs available to divers. They all have advantages and disadvantages. Some are well suited to cave diving, some are not. In my opinion, none of them is perfect out of the box. But that's just the nature of sidemount. The current systems widely available to divers are Dive Rite Nomad, Hollis SMS100, OMS Profile, Oxycheq Recon. The Armadillo can still be found in some locations. There are also some privately made harnesses, such as the Razor, but wing choice and attachment is left to the diver.

As I stated previously, none of these systems is perfect out of the box. I've made several modifications to my Nomad and have other modifications I want to make, but have been too busy diving to bother making them yet. While the modifications I've made on my rig work for me, they may not work for everyone. There's a saying, "Get 10 sidemount divers together at a dive site and you'll see 11 different ways to rig up your gear." You need to choose what works for you and your type of diving.

One of the things I teach in my sidemount course is all of the possible ways to rig gear and why. I have tried several of them myself. For example, I've pointed my SPGs in every direction possible. There are advantages and disadvantages to each of them. One of the key factors in which way you point your SPGs is your valve orientation. I've tried a few different valve orientations, too. I finally have things set up in a way that work for me...right now. In six months it may be different. This is what makes choosing a sidemount instructor that has experience sidemount so important.

Over the past year there has been a surge in the number of sidemount instructors. Many of these instructors became sidemount divers and sidemount instructors the same weekend. They have very little experience diving sidemount and may not even dive sidemount outside of classes. Even fewer dive sidemount in caves, the original environment sidemount was conceived for. (I'll add a blog on the history of sidemount diving in the coming weeks.) Sidemount diving is more than just strapping cylinders to your sides and getting in the water to complete drills. A big part of the course should be setting up the gear before ever getting in the water and then tweaking it between dives to work for you. An instructor who has very little experience diving sidemount isn't going to be able to help you do this. If that's all you want the course for, just buy a book and read it. You'll probably get more out of that. However, if you want to learn how to set up your gear so it works for you and you want to save yourself several dozen dives in trials, find an instructor who has experience and dives sidemount to it's fullest capabilities. Don't only ask the instructor, but talk to other divers about the instructor. Unfortunately, there are too many instructors out there that will misrepresent their experience just to get students.

Well, I'm off to teach a sidemount course tomorrow. Keep checking back here for more information on sidemount diving.

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Welcome to the Chipola Divers Blog!

While we try to keep our website up to date with the training options we offer and all the latest dive site conditions, we felt we could do more to provide visitors to our website with more information. We will continue to update our website on a regular basis, but we are also going to add information here for those of you that like the blog format better. Keep checking back here for information on our courses, reports on our dives, and more information on many different aspects of diving. Thanks!

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