TDI Diver News

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SDI vs. TDI vs. ERDI – What’s the difference in the diving courses?

We get questioned a lot on what the difference is between SDI, TDI and ERDI courses, so we decided to put it out there where it’s easy for everyone to find when they start doing research.


3 Shorts

Recently, there has been a large increase in the number of accidents involving dive boats backing down on or running over divers. This of course is not limited to the US; these cases span the globe.


Extend Your Limits With Trimix

In reality, Trimix is a risk management breathing mixture utilized by divers typically seeking to offset the consequences of diving normoxic air or nitrox mixtures at a planned diving depth by replacing much of the nitrogen and some of the oxygen with more benign inert gases like helium.


Cave Training at a Young Age

I constantly have to remind myself that gushing about my new dive toys to my friends at lunch will only be met with confused facial expressions, while discussing teenage gossip with a group of seasoned divers will have the same result.


Caves and DPV’s: What You Should Know

With a DPV, as with overhead environments and rebreathers, a diver must master the basics first and foremost


The Top 3 Finning Techniques and When to Use Each One

A diver should be able to move through the water using their fins as the exclusive means of propulsion to increase efficiency and minimize the impact to the environment.


Is CCR Diving Right for You?

Fortunately, there is a way you can discover whether CCR diving may be for you without ever having to make that investment. It’s called the TDI Rebreather Discovery experience.


Skills Necessary to Conduct CCR Dives Utilizing Helium

There is no fluff when it comes to CCR diving. Each step has value and should be followed as prescribed. And that’s not just my opinion, it’s the best, safest and most secure way.


When Silly Drills Become Serious Skills

by Chris Richardson:
cave diver

A few years ago, okay… close to a decade (I’m getting old) I got together with a friend to have him evaluate me for some new Instructor Trainer ratings for technical diving. I had a few choices of who I could get together with to be evaluated but chose this particular evaluator because he has a reputation of being tough, was a friend, and he and I hadn’t been diving together before but knew each other well from being in the dive industry. Frankly I wanted to see if I was up to it.

We met up very early over breakfast and discussed the day’s plans. After lunch, real students would be joining us and he expected me to teach the class, but first we would go over and jump in confined water where he wanted me to demonstrate drills and skills.

When we got to the confined water site I was told to bring not just one stage, but two stage 80’s and a 40. I was in twin 104’s and drysuit. In other words, fully configured (kitted for those of us from the commonwealth) for a full on multi-stage dive.

First we did a buddy check and S-drills. Then he asked me to demonstrate, while neutral in trim, at no less than 8 ft and no deeper than 10 ft, stage management and gas switching from back gas through all three of the stage/deco bottles. Anybody that has ever dived with me knows that I ALWAYS want to do a warm up dive or two before doing any teaching, big dives, or being evaluated. This day I was going in cold and to my great relief I had no great difficulty managing the skill and surfaced to an evaluator with a somewhat evil grin on his face. He informed me that that was “pretty good” made a couple small suggestion for improvement then told me to do it again… without fins on! I must have looked at him like he was crazy because he laughed and asked if I had ever tried it before. I said no, of course not. He then informed me that “all” his students have to and that was that. Well… off my fins came, I settled down to the required depth, got myself in trim and neutral with some difficulty and then started the gas switching.

Yeah that didn’t work out so well.

It was humiliating and I provided great amusement to my friend. When he stopped laughing at me he informed me that I passed. I gave him a look and asked “WTF are you talking about?” He started laughing really, really hard and informed me that he does do the no fins but does NOT expect the student to do gas switches… then started laughing again. We had hadn’t fully communicated, he expected me to simply get there and get stabilized in trim and buoyancy, I thought he wanted me to fully do the earlier skill only without fins.

I then stated that, “I think I can do it, let me try again”. He raised his eyebrows and said, “Go for it”. I did, and I did. I took my time and if it had been a real dive with gas switches done so slowly I would have had to add another deco bottle to offgas the extra ongassing from how slow I was, but I did it. He was surprised and said he wasn’t sure he could manage it, he tried and he did it after a couple tries, we laughed and then the students showed up and we enjoyed the class.

I liked the skill as watermanship development for technical divers and use it when I teach (without the gas switch) but do tell people they should try it when they get comfortable with just the trim and buoyancy no fins drill. I also demonstrate both of these to my students to show it’s possible (I do only one stage however) I have had frustrated students protest that “the skill is stupid, why would you dive without fins?!”

Fast forward to two days ago.

Myself, and Edd Sorenson from Cave Adventurers in Marianna, Florida, were doing a fun dive together. The plan was he would show me some new cave in a well known cave system he had discovered and laid line in. The plan was fairly simple, we would scooter out a couple thousand feet with a stage, drop the stage and the scooters and go swim the new passage, come back, get stages and scooters, head back and deco.

The new section Edd found is pretty tight… not crazy stupid tight but certainly snug. We had to pay careful attention as to not stir up the bottom silt. There was one spot that was quite tight, almost crazy stupid tight. We reached the end of one line, turned around and Edd headed out with me behind, coming up to the restriction Edd slipped through, I followed and in the tightest spot it happened… I felt my left fin slip off my foot. I knew what happened. It’s a prototype fin that I had been testing, the strap was a little too big but not horrible and I knew that but wanted to dive the fin anyhow. The tight spot meant that I needed to stick my head and torso down, and then arch upwards to get through. Air went up my drysuit leg and into the boot and it popped the fin strap off. I couldn’t bend to reach my foot (okay, it was crazy tight there) so backed out to look for and put said fin back on. At this point the old saying “SILT HAPPENS” came true and needless to say, I couldn’t find it. After not finding it I came out of my silt cloud, showed Edd my “issue” and he decided to go get my fin… well that didn’t happen either. The good news, it’s not hard to move through low passage with one fin on, really. But as soon as we got out of the new passage into the main cave system which was much bigger the lack of a fin was MUCH more noticeable.

Using skills developed doing a silly drill, I retrieved my stage and my scooter, performed a gas switch to my stage, and started the scooter ride back. If you’re curious, scootering with one fin is easy at slow speed, not so easy at a medium speed and downright difficult at full speed on a good scooter.

The exit was uneventful; I was alternating between slightly embarrassed and quite amused I lost the fin. Upon surfacing, Edd ‘s first words were, “You made an event a non event”

We talked it over, I told him about the no fin skill, I admitted I was stupid to keep diving a fin I knew wasn’t a perfect fit and we discussed the event in the context of how we each could use it in teaching students so hopefully they could also turn “events into non events”. We also laughed about the fact that NOBODY but Edd or I would ever find that lost fin.

I’m writing this in the hope that other divers can learn to appreciate how important those safety, watermanship, and comfort skills we practice are. The place to fail a skill or a drill is in confined water while training, don’t short change yourself. Practice hard so you can dive easier.


4 Things I wish I’d Known Before My First Tech Dive

by Sean Harrison:
Tech dive

As I look back on the days when I first started tech diving, two things come to mind that have had significant changes – equipment and logistics. There have been such dramatic changes in equipment it is hard to highlight them all. The early tech equipment was nothing more than standard equipment that was reconfigured to meet our needs, it was not specialized, light weight, easier breathing at deeper depths or made of special metals. And we certainly did not have rebreathers, those did not come ‘til the late 90’s. Logistics, on the other hand, has gotten better but can still be a little tricky. My tech diving started in the mid-Atlantic states of the US where there were several boats that would take us to deeper wrecks and allow us to stay a little longer in the water. We also had a hard time getting the gas fills we needed for the planned dives. Things have gotten better in this aspect but here is a list of things to be aware of if you are considering getting involved in tech diving or have recently learned to tech dive.

1. Boats – not all boats are created equal. Dive boat operators as a general rule rely on the number of divers they take out per day, pretty simply math – the more divers they take out, the more money they make. When boat operators take out tech divers they will usually reduce the number of divers on their boat (space for additional equipment) and stay out a little longer to allow for decompression or rebreather divers – this means you may pay a little more to do tech dives off of boats. This also means you need to speak with the boat operator and make sure you can do the dives you want to do off their boats. Mixing tech divers with sport divers normally does not produce good results.

2. I have to go! – tech dives are not always deep but they are almost always longer than your average sport dive. Longer dives means better exposure protection (even in warmer water) read: dry suit, which means no peeing in the water, or does it. TDI recently released two good articles on this:

The P-Valve Struggle »
Girls Pee, Too »

The short version of these articles is, it is important to stay hydrated while diving and with hydration comes nature’s call. Lots of options to manage this situation so do your research before your next long dive.

3. I’m hungry – anybody that knows me knows I love my food and after a few hours in the water, I surface ready to eat! Diving burns calories and the colder the water the more calories burned. Tech diving from boats in many places also means longer boat rides, so getting back to the dock is not going to happen as fast as it does on sport dive boats. Bring along some good snacks or a sandwich to get you back to the dock. If you have a good snack on the boat ride back, you will be able to get started on the monster nap sooner.

4. Bring on the gadgets – not so fast. Tech divers are certainly gear geeks but they also tend to be minimalists and only bring what they need. A big part of what allows us to tech dive and stay underwater longer is minimizing air consumption; carrying more gadgets means not being as streamlined and increases air consumption. As you select gear, think about what kind of diving you will be doing, cave divers don’t need what wreck divers do and cold water wreck divers don’t need what warm water ocean wreck divers do. Also think about where it is going to go on your body or configuration. Too many things stacked on top of each other means you may not be able to access it when you need it.

If you are a planner or someone that likes to work through scenarios, technical diving is right up your alley. Plan out your dives, call the boat operators or local stores (if you can do the dives from shore) and find out what sort of support they can provide. If you will be diving from a boat, make sure you are clear with the operator what kind of dive you want to do and see if they will do it. Planning ahead is critical when it comes to rebreathers and traveling, not all locations support all rebreathers. Make an equipment check list and go through it before every dive/trip, with tech diving comes more equipment which equals more things to forget. Make sure that check also includes a save-a-dive kit, and that the spare parts now include the ones you need for tech diving. Plan ahead and have fun. A spontaneous tech dive can result in a spontaneous disaster. If you have not yet taken a tech diving course, consider signing up for the TDI Intro to Tech Course. This course will give a great overview of what to expect and what you will need.