The Long Path To Trimix Diving, Part 3

In early April 2013, I met Mark McAlpin and Didier B. Follain-Grisell, owners of Go Dive Florida (formerly Fill Express). As with all true divers these guys are characters and good people. They would be instructing Carl and I for our TDI Extended Range and Trimix course. Finally, being certified to dive deep was going to happen – so long as the Ocean Gods permitted.

Go Dive Florida

Go Dive Florida is the idea of Mark and Didier. Located in Ft Lauderdale, they offer a range of instruction from beginner Open Water students through advanced technical diving. They also have one of the premier gas fill operations along the east coast of Florida. They pride themselves on exact mixes and they offer tec diving events all the time. They also service equipment to specs. If you are in the area do yourself a favor and stop by. The fill set-up is the best I’ve seen.

Mark McAlpin

Mark owns Go Dive Florida with Didier. I first met him on the Thursday I drove down with my gear to start the class. I arrived at Carl’s about 11 AM and met Mark and Didier for lunch. This was a meet and greet. When someone is going to instruct you on decompression diving they need to assess you beforehand. Diving at these depths is hazardous for all involved during training. He knew Carl and probably relied on a lot from him. I’m guessing Carl gave me good reviews because we were soon at his shop in the classroom. Three and a half hours driving, going for lunch and then straight into a classroom. I could only hope to stay awake.

Didier B. Follain-Grisell

Didier also owns Go Dive Florida. He is a great guy, funny, and a good instructor. He taught the class on that Thursday afternoon and kept it lively enough so I did not have to do two-eyelid pushups all afternoon. Didier is a character. He makes you feel comfortable and teaches very well. Under water he and Mark are excellent.



Didier showing us how it is done.

The classroom instruction started the day I drove down to Carl’s. After Lunch we all headed to Go Dive Florida and went up to the classroom. Great set up. Unfortunately, TDI has the same boring video presentations/power-point/whatever as PADI. This is where the instructor shines. Can he or she make this presentable?

On the face of it, the presentations are like the basic training class on the breakdown of the M-16. Remember the big oversized mock-up of an M-16 at the front of the hot, air condition-less, classroom where drill sergeants roamed, ready to pounce on anyone with their eyes closed. Where they told you to stand up if you were falling asleep. Remember those days (for those ex-military types)? That is what sitting through a PADI or TDI training video/power-point/whatever is like (at least at this level).

Luckily, Didier made a great instructor. He kept us awake with humor and his Pink Panther wit. Mark, who was around the corner at his desk helped by throwing a few shout-out zingers himself during the class. And we had a special guest show-up too that I talk about below.

The Formula

If you are thinking about technical diving or doing it blindly there is a formula you will have learned early on during dive master training that you probably never fully grasped. HINT: grasp it. Dalton’s Law combines Boyle’s Law and Charle’s Law to create the General Gas Law. (If you don’t know what I’m talking about you’ve probably only thought about Dive Master.) Dalton’s Law states:

The pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the different gases making up the mixture – each gas acting as if it alone were present and occupied the total volume.

Regardless their is a neat formula that provides key data when you need it:

If you want to find the partial pressure of a gas [PPg] based on the fraction of gas at 1ATA [%g] at depth [ATA] – PPg = %g x ATA

If you want to figure out the fraction of a gas – %g = PPg/ATA

If you want to find the depth at with you reach a specific PPg – ATA = PPg/%g

We all know that the max PO2 we want to dive with is 1.4 to 1.6 depending on what we are doing. The max PN2(itrogen) suggested by TDI is 4.0. So a dive to 7ATA with our %O2 = 21% gives us our PO2 of 1.47. That’s acceptable. But if we used air as our gas our PN2 would be 5.53 (7 x .79 = 5.53) which is unacceptable. Using a PN2 of 4.0 we come up with our %N2 being 0.57. However, since the sum of .21 and .57 only equals .78 we have to use another gas to fill the void (Since we have not reached the whole number 1 we have to add another .22 of gas). Hello helium.

(Do not follow these examples. Get trained. I’m still learning this and I am not a technical diving instructor.)

John Chatterton

Just about every diver that has moved past rescue diver has read “Shadow Divers.” Anyone who has read it knows who John Chatterton is. Carl had told me that he runs into John all the time at Go Dive Florida. John now lives in Florida and lives the life of diving, er, oh wait, …continues living the life of diving.

I did not expect to see him while I was there for those four days but lo and behold, during the classroom session, in walks Chatterton. At first I did not recognize him until he started talking to Didier. Then it became clear. His voice was definitely “Deep Sea Detective” -esque. He was doing an advanced trimix course that same weekend (unlike the trimix class I was taking, advanced certifies you to depths of 330 feet). He walks in during class and talks to Didier about the class, who we are, where we’re diving, he jokes with Mark, etc., etc. All in all, it was pretty damn cool. For me, it was like meeting a rock star only a bit better. During the four days there we would run into him a couple more times. I was able to approach him and talk to him like divers. He has an air about him only to the extent that he has become quite a name in the diving industry but other than that he was very friendly.

Dives 1 and 2

The first day of diving involved two recreational depth dives. The first was to a wreck at 125 feet. Both Mark and Didier wanted to observe us diving in a technical rig. Actually, more me since they had already dove deep with Carl. The second dive was on a shallow reef, maybe 60 feet.

No Mask Swim: Blinded By The Sea

On the the deep dive to the wreck we did a few skills involving doffing and donning the deco bottles and deploying the surface marker buoy [SMB]. On the second dive we had a fifty foot no mask swim with a regulator exchange at the end of it. I always like testing myself where a mistake is going to be one gagging coughing mess (sarcasm). Carl had already done this with Didier and Mark. I had done it in 40 Fathom Grotto (albeit on the 20 foot platform) and multiple times in Lake Denton (eyes closed in that soup).

Mask removal and replace does not go away after Open Water instruction.

Mask removal and replace does not go away after Open Water instruction.

This time Didier would mark off 50 feet (he actually marked it off, no estimating) and he would stay at one end pointing a flashlight at the other end and moving it in a circular fashion. I would go to the other end, take my mask off, open my eyes, and follow the light. My biggest worry was the thought of my eyes burning from the sea water. As a kid I use to open my eyes all the time at the beach, no big deal. As an adult I forewent that. As a scuba diver the only time I exposed my eyes to sea water was when I had to defog my mask at depth by letting water in the mask and swishing it around. The little left that would get in my eyes would burn like fire. Luckily, on the 50 foot no-mask swim, that didn’t happen. My eyes were surprisingly fine except for the fact that all I could see was a brown blur everywhere and a little blurry point of light making circles in the distance.

Breath in mouth, out nose, in mouth, out nose. To me this is the easiest so long as I don’t mess up the pattern. That makes for a bad day. Mask off, breathing – check, eyes – blind, swim like a drunk turtle. I swam and swam. The little light moving in circles did not seem to be getting closer. I swam more. Didier did not come into view until I was almost upon him. I could make out the regulator he was handing me, grabbed it and made the exchange. Then put on my mask and cleared it. Done. Lessons learned: No burning eyes in the ocean and the knowledge that I can’t see a damn thing without my mask.

Deploying The SMB From Hell

The last skill on this first day of diving involved deploying the SMB. This is an important skill. WARNING: No one should just buy a reel and an SMB and go diving with it without practicing. I practice it all the time at Lake Denton (yeah, yeah, boooooring) but that is better than an entangled ride to the surface from 100 feet or more – straight to the chamber.

As I prepared to deploy it something happened. I connected the SMB to the reel but when I looked back at the spool it was the classic Goat Screw. Line was spilling out everywhere. I could not deply it before this issue was taken under control. I made the command decision to forget the class and drop two feet to the sand and fix this. On a real deco dive this would add minutes to my bottom time and potentially more time than gas to my decompression times. It took me a few minutes of untangling line and fixed the problem and deployed the SMB.

This is probably the one skill I will always practice every chance I get. I want to get to the point that deploying an SMB will be like blinking my eyes.

The final skill was gas shut-downs. I had problems reaching my doubles with my dry suit on (see Part 1 and Part 2) but it proved to be quite easy in a wet suit. However, flexibility is a fading talent so periodic self-testing is a must.

Dive 3: The Hydro Atlantic

The second day of diving I finally got the chance to dive the Hydro Atlantic. The is a wreck sitting in about 175 feet of water. The deck is anywhere from 140 to 130 feet. There is superstructures above that depth also. We were going to the bottom. The dive master on the boat (from Pompano Dive Center) dropped and hooked the line to a tall mast. After our bubble check we went down to the end of the line and then down to the deck. No current. Once

down we took an assessment of each other then proceeded over the ocean side to the bottom. Our mix for this dive was 21/35 (21% oxygen and 35% helium) with deco mixes of 80% and 50%.

Lionfish Paradise

At the sand we swam south along the hull to the bow. I saw a Lionfish, then another. I started counting. I gave up a

A picture after the dive.

A picture after the dive.

few feet later. I was at 9 and as I looked ahead all I could see were Lionfish. As we reached the bow we ascended up onto the deck. I did not notice any Lionfish on the top side.

We swam back along the deck to the stern. Either Mark or Didier released the line. We then deployed our SMBs. The great thing about deploying from depth is that all it takes is a breath or two to have an 8 foot SMB completely filled up by the time it reaches the surface. Once released I watched the reel to make sure it was not tangled and to know when the SMB reached the surface. If the reel tangled at that point the immediate solution is to let it go. The risk is a few hundred bucks are lost and you are not bent. And you get to try again with a second reel and SMB.

The ascent went off without a hitch. At 70 feet we did our gas switch to 50%. At 30 feet we went to 80%. Just FYI – if you are going to do this kind of diving do not skimp on your computer. Mark hooked me up with a Shearwater Petrel. Best damn computer I have ever owned. It does everything except make your lazy-ass bed.

Beating Chatterton’s Divers To The Fill

When we finished the first days dives, got our gear off the boat and headed back to Go Dive Florida to fill our tanks for the next day. As we pulled up the shop looked quite busy. It was. Chatterton had gotten there first with his class. This was a definite learning moment (hours). We were second in line and it was a long line.

While waiting I got a chance to introduce myself to Chatterton. We talked a little about another book that was coming out but mostly we were waiting for his students to get their gas fills. Finally, they were done. We filled and went home (to Carl’s).

After the second day, Carl and I were determined to beat Chatterton to the fill and we did. Being first is a good thing as it was this day. Sometimes, as I will show below, being second is best.

Dive 4: The Lowrance

This is part of our gear. It is an expensive hobby.

This is part of our gear. It is an expensive hobby.

The mix for the Lowrance, which sits at 200 ft, was suppose to be 18/45. It ended up being 18/43. Mark and Didier wanted to drop without a line but the captain felt the current was too strong and we were required to use the line. The placement of the line was a drag. The captain had the line dropped and then drug it until it hooked on the wreck.

Because of our mix (only 18% oxygen) Didier told us to drop heavy, get to 10 feet and then head for the line. At that depth the PO2 should be around 21%. I expected a hard current but once in and at depth getting to the line thirty feet away was no problem.

The line dropped straight down from the surface. Getting down was easy until about 150 feet. That was were the current kicked up. The line started to lean in one direction. At about 175 feet the line was horizontal. The Lowrance was not in sight. We were now dragging ourselves along the line into the current. Soon the outline of the ship appeared and we continued our climb. Within 25 feet of the ship I could tell I was getting winded. I slowed down, got to the ship and found a spot outside of the current. I hid there and relaxed until my breath came back.

I checked my buoyancy and followed Mark and Carl, in that order. Didier followed behind. Down one deck and out the side, we descended to the bottom. In a line I watched those ahead of me.

The Hole At The Bottom

Didier (Go Dive Florida), Mark (Go Dive Florida), Carl and me after completing our ER/Trimix class.

Didier (Go Dive Florida), Mark (Go Dive Florida), Carl and me after completing our ER/Trimix class.

As we got to the sand along the hull I saw Carl following Mark. Then I noticed that he stuck his arm down toward the sand. I knew what he was doing. He was trying to get a bottom depth. Where he did this was a current washout along the hull. This is where the current has created a little eddy and pulled sand away from the bottom. As I approached this I went full bore. I stuck my arm all the way down into that hole. I’m surprised Didier did not follow up with a deeper attempt. In the end Carl’s depth was 201 feet. My depth was 204. (Second was better)

At the end we deployed our SMB and ascended. Our deco mix was again 80 and 50%. When we surfaced we knew we had attained our goals (and then some). On the boat we took pictures and enjoyed the ride back. After three years, the goal had been achieved.

Parting shots…

Making the jump from recreational diver to decompression diver should not be taken lightly. Despite saying that many young guns will jump right into it without too much thought. Diving at depths below recreation limits is a science. Learn the physics and physiology of diving. Practice basic skills over and over. Finally, stay in shape. Getting out of the ocean and onto a boat with all this gear is not for wimps (translation = exercise).
Story by . Follow him on Twitter @DirgaDiver.




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