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georoc01
May 30th, 2010, 12:27 PM
DSAT Tec Deep
Coconut Tree Divers - Roatan, Honduras
05/15-05/29/2010

Itís Saturday of my Tec Deep Class. We are doing our first true deco dive after a week of training and preparation. The plan is to do a wall dive down to 140 feet for 20 minutes. Monte, my instructor in reviewing the logistics, instructs our boat captain to drop us off in the blue off of a dive site called Dixie. We drop in and start doing our S-Drill and tank checks. By the time we start our descent, there is nothing but blue. The adrenalin rush of dropping down that far in pure blue was intense as the only real bearings were my compass, the sun above and my instructor. We swam east during the descent and after leveling off saw the wall starting at 130, rising 110 to 20 feet below the surface. Itís an amazing site to see that much reef from that perspective. We continued our swim up to the wall, and did our training exercises. In this case, it was to drop our deco tanks, do an unconscious diver tow for about 50 feet then do a set of timed valve shutdown drills under 45 seconds, before collecting our bottles and beginning our ascent. After completing our mission, we began our deco ascent, following the schedule we had planned in the morning, breathing the deco blends we had filled and verified beforehand. Doing deco along a wall is a great experience as it becomes just one extension of the dive. 56 minutes later, I had completed my first deco dive.
The week prior had been rigorous. We started that previous Sunday going over the 1st two knowledge reviews from the book, then starting dive planning. He had built a dozen cases. The first three were practice. The remaining were training dives 4-12 in the class. That afternoon we began our confined work in the shallows across the street from the dive shop. After an hour of doing valve shutdown drills, shooting smbs, etc, we then went back and did our first boat dive with a deco tank, dropping down to 30 feet we practiced dropping and picking up the al 80 deco bottle. I had my buoyancy dialed in pretty good with the doubles on my back, but adding the deco tanks really started to make things challenging. And picking up and dropping the tanks on the fly made it even harder. By dive 2 we were carrying 4 tanks. An AL 80 at 32% O2 and an AL40 with a richer blend. We started with 60% and worked our way up to 100% by the last two dives.

For dives 1-8, the deco was simulated. We had a set schedule we would copy onto our slates prior to every dive along with a mission of skills to be done. Awareness was added in by having to write down depth and gas volumes at various times during the dive. We did SAC rate calculations daily with valve shutdown drills on every dive. Between the class work and the diving, the first week was challenging. While I was getting encouragement from my instructor, it was still discouraging, as if I started diving all over. We did take a one day break where I did some fun recreational single tank diving during the first week. That restored my confidence that I still remembered how to dive and that this was actually fun.
Dive 10 was a repeat of Dive 9, down to 140 feet. We did extend our time at depth by 5 minutes and adjusted our deco stops accordingly. This time it was my turn to lead the dive and call out all of the stops. It went very smoothly and I was feeling like I was finally getting the hang of it. We also recovered a lost prop in the sand and killed a couple of lionfish.
Dive 11 was on a wreck called the Josie J. The profile was to a max depth of 165 feet. We lowered a bottom depth gauge into the wheelhouse of the wreck which measured at 180 feet. Being it was deeper; we could only swim over the wreck and couldnít penetrate it. But it was still lots of fun to see the wreck appear out of the blue do the dive and once again, we had a wall to follow during our deco stops back to the surface.
Our final dive in the class was to a site called Pillar Coral. Off for some serious lionfish hunting. We dropped into what we called a lionfish condo, with over 13 lionfish living together at 164 feet. Monte had the spear gun; I had the knife and watched the clock, as we killed as many of these pests as we could. I think Monte got 6-8 before time expired and we had to head back up the wall.
Overall the class was very well thought out and I thought fairly thorough. If anyone is looking for a warm water destination for their tech training, you might want to consider Coconut Tree divers in Roatan. I know after diving as deep as we did on air, trimix, which they also offer, will probably be next in my training adventure. But in the meantime, I felt I learned a great deal and look forward to my next adventure.

Peter Guy
May 31st, 2010, 01:38 AM
Thanks for the report. I am, however, a bit confused. I thought that DSAT had switched over to the Tec 40/45/50/65 (?) and no longer did "Tec DEEP." Or did you do all those and the shop just called it "TEC Deep?" as it seems that those 4 classes are the same as the old one?

In any event, congratulations.

Question -- How did you do your valve drills and what is the purpose behind the "timed shutdowns?" For what it's worth (which ain't much) the only "timing" I had was to shut down the offending post but nothing was ever, in fact, timed.

georoc01
May 31st, 2010, 09:08 AM
The only difference between Tec Deep and Tec 40/45/50 is the order in which the dives occur. The progression changes as you complete each step going forward in the new program. Since we were going through to Tec 50 anyway, we did the old progression that the instructor preferred. Tec 65 involves Trimix which wasn't included in this course. If done as part of the progression, it would have been an additional 6 dives. Doing it seperately adds 2 dives to the Tec 65/Tec Trimix class.

Valve shutdown involves isolating the manifold and then shutting down each side. The course requires you to do it in 60 seconds at the start of the course, working down to 45 seconds by the end of the class. This is one thing that for me, was far easier in a 3MM wetsuit than it was in my dry suit.

Peter Guy
May 31st, 2010, 09:35 AM
Thank you for the info.

Did your instructor explain why it was important to be able to shut down ALL the valves in a timed manner as opposed to be able to shut down just one (in this case, I guess, isolate first)?

georoc01
May 31st, 2010, 12:56 PM
Many times its difficult to determine which side has failed. So you isolate and then shut down one side, and then the other until the problem has been isolated. Speed is of the essence as a majority of your air can be lost in a hurry.

Another drill we did was where my instructor would hover above me and simulate a free flowing manifold using his regs. It can be challenging to see behind you which side it is. Teammates could obviously be a help if this happened for real, but they teach self-sufficiency first.

rongoodman
May 31st, 2010, 01:36 PM
I did some guided dives after the cave classes recently in Mexico, no failures, no stress, just practice. On the second day, just before we we surfaced in the pool at Grand Cenote, I heard a rush of bubbles behind my head. I shut down the right post, breathed it down, and switched to the secondary. At the surface, there was Santiago with a big grin and an air gun--he had evidently spent quite some time looking for it at home the night before, since it had disappeared during a recent move. He was happy with either, but I think I'll be staying with the GUE scheme of shutting down the right post first unless I know it's something else. It seems like the fastest way to fix the most likely problem.

AndyNZ
May 31st, 2010, 08:33 PM
Many times its difficult to determine which side has failed. So you isolate and then shut down one side, and then the other until the problem has been isolated. Speed is of the essence as a majority of your air can be lost in a hurry.

Personally, I disagree.

In my experience, it is very rare that it is hard to identify which side of a manifold has failed - it's a simple case of listen, feel and look. Having had multiple airgunned (simulated) failures ranging from tiny bubbles to torrents of gas, I'd say that about 95% of first stage failures are easily and correctly identifiable.

It's my opinion that taking a few seconds to identify the failure will not result in as much gas loss as isolating first when you don't need to.

Speed is one perspective, but I personally feel that precision is better. Shutting down multiple valves and opening them again in a hurry increases the risk of inadvertently closing off both valves and having nothing to breathe, which is something I would prefer to never happen to me (again - once was enough).

Sas
May 31st, 2010, 08:58 PM
In my experience, it is very rare that it is hard to identify which side of a manifold has failed - it's a simple case of listen, feel and look. Having had multiple airgunned (simulated) failures ranging from tiny bubbles to torrents of gas, I'd say that about 95% of first stage failures are easily and correctly identifiable.


I agree absolutely. I have never had trouble identifying the location of any simulated failures (with air gun) I have experienced nor have I had trouble identifying the two real failures I have had. If I had any doubt I'd shut down right first...

ucfdiver
June 1st, 2010, 03:00 AM
Many times its difficult to determine which side has failed.
Really? :dontknow:

rjack321
June 1st, 2010, 11:21 AM
The one real failure I had was really easy to diagnose even with a 7mm hood on (left reg, fixable).

Shutting the isolator first actually wastes gas if the problem is anywhere downstream of the manifold i.e. the regulator. It only saves gas if the problem is the manifold itself or tank neck o-rings. I only isolate if shutting down the offending post doesn't stop the leak, hence I know its the manifold itself or that I misdiagnosed the leaking reg/post.

Colliam7
June 1st, 2010, 08:10 PM
I am, however, a bit confused. I thought that DSAT had switched over to the Tec 40/45/50/65 (?) and no longer did "Tec DEEP." The switch is occuring. But, you can still teach Tec Deep through the middle part of this year. We just went to FL and finished up the thrird group of 3 divers (a class of 9) in what will probably be our last Tec Deep sequence.

amascuba
June 21st, 2010, 02:48 PM
One of the few times that you will ever have a left post when it's really a right post failure or vise versa is when you have a low pressure hose split that runs from right to left or vise versa. Other than that it should be pretty easy to diagnose which side the bubbles are coming from and you shut down that side. If the bubbles persist, then you isolate. After all, you have enough gas for you and your buddy to make an ascent to the gas switch and complete all deco, right?

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