DSAT Tec Trimix Diver Adventure

[theskull]

James suggested I log my new Adventure experience for your reading pleasure.

So here goes:

My reason for taking the certification adventure: the cert is required by the operator with whom I'll be diving the Andrea Doria this summer (The Seeker). The Doria sits in app. 245 ft. of North Atlantic Ocean.

Prerequisite for the course is Tec Deep Diver or equivalent. In my case I have had the equivalent for 3 years, IANTD Normoxic Trimix Diver.

As a Normoxic Trimix Diver I was "qualified" to dive to depths up to 200 feet with Helium mixes that had an Oxygen content of at least 16%. For a gas mix to be breathable at the surface it must have at least 16% Oxygen (most agencies now say you must have at least 20% Oxygen in the mix for Normoxic). For the record, I have stayed within these depth and mix limits. For those of you who have not yet taken a Nitrox class, Oxygen becomes toxic at a high partial pressure, so it is critical that you don't dive too deep for the Oxygen content of the gas you breathe.

As a Full Trimix Diver I will be "qualified" to dive to any depth with any appropriate gas mix. Obviously if you are using a hypoxic gas (probably your back gas) you need to breathe a different mix during the initial part of the descent until you are deep enough for the partial pressure of the Oxygen in your hypoxic gas to be breathable.

That's the background. Now for the dives (cont.)

[theskull]

The course requires at least 8 dives to depths of up to 245 ft., wearing doubles and at least 2 stage bottles for all dives and skills.

Today at Oronogo Blue Water Quarry, north of Joplin Missouri, I performed the following skills during our first dives:
(I may miss listing some since many seem routine at this point)
Dive planning
Buddy check
Bubble check and Safety Drill
Tow unresponsive diver at surface
Descent check
Remove & replace stage bottles at depth while neutrally buoyant
Valve drills
Out of gas drills as donor and recipient
Share air while swimming and while swimming without mask
Attach another 2 stage bottles and swim with 4 stages on
Deploy lift bag
Make staged decompression stops breathing from appropriate stage bottles while towing the lift bag attached to your reel
Respond to various diving emergencies/issues at unplanned points in the dive

Today was tiring, both from a physical effort perspective and from the prolonged mental alertness. Oh yeah, and carrying all the gear down and up the big hill at Oronogo.

Today's dives were made using air as backgas. Tomorrow will be on Trimix.

The plan for tomorrow includes preparing deco tables for the dives as well as plans for dealing with missed deco stops during the dive--both by using mixed-gas dive computers and by using tables.

To be continued,
theskull

[Atlaua]

My reason for taking the certification adventure: the cert is required by the operator with whom I'll be diving the Andrea Doria this summer (The Seeker). The Doria sits in app. 245 ft. of North Atlantic Ocean.


I guess the days of doing the dive you want on the gas you can afford are long gone...In many ways that is a good thing....in some way's its a little sad.

James

P.S. I hope you said hi to Marty and Marc..

[M&P+4]

The course requires at least 8 dives to depths of up to 245 ft., wearing doubles and at least 2 stage bottles for all dives and skills.
theskull

I bet after a long day of lugging all those cylinders around you have to wonder awful hard about going the rebreather route....that would get you the same depth and bottom time, wouldn't it?

[theskull]

I guess the days of doing the dive you want on the gas you can afford are long gone...In many ways that is a good thing....in some way's its a little sad.

James

P.S. I hope you said hi to Marty and Marc..

The sad part is that it's all about liability. The evil lawyers would be quicker to jump on an accident case of an operator who allowed me to dive to 220 feet while only "qualified" to dive to 200 feet.

theskull

Marty and Marc?? Never saw them. Pretty sure I spoke to everyone present there today.

[Atlaua]

Yep, that's what I ment...safer diving is always a good thing, but the NA sue happy socity part isn't... I just switched to private insurance, recent changes here locally forced that, now I can work for any of several shops instead of having to work X classes at one to be on the umbrella policy.

By doing that I moved from all diving income is gravy to all diving income is trying to cover costs....

Plus...well Chris and Chrissy paid dearly for being broke, but it was their right to decide...IMHO..

Unless somthing happened Marty and Marc were there for training... You had to have seen them, but they were only there Saturday as I recall. Marty was the guy sitting to my right at the Forum Thursday...

James

The sad part is that it's all about liability. The evil lawyers would be quicker to jump on an accident case of an operator who allowed me to dive to 220 feet while only "qualified" to dive to 200 feet.

theskull

Marty and Marc?? Never saw them. Pretty sure I spoke to everyone present there today.

[theskull]

I bet after a long day of lugging all those cylinders around you have to wonder awful hard about going the rebreather route....that would get you the same depth and bottom time, wouldn't it?

Nope!

To make dives at this depth on rebreather you have to bring along enough bail-out gas and deco mix to complete the dive in case the rebreather fails. Same number of cylinders required. Far more expense involved and, you guessed it, more expensive training required as well.

The primary benefit to a rebreather for this type of diving, if you plan to do a great deal of it, is you don't have to buy nearly as much helium since you are re-breathing it instead of exhaling each breath. The primary deterrent is that there are many more opportunities for a rebreather to fail and do so catastrophically than for open circuit.

theskull

[Atlaua]

TS,

Are you planning on bringing any kind of recording eqipment with you when you dive the AD? Yea we've all seen the shows but a local experience just brings those of us who have no desire to hassle with the proper training and eqipment that much closer...

James

[theskull]

Yep, that's what I ment...safer diving is always a good thing, but the NA sue happy socity part isn't... I just switched to private insurance, recent changes here locally forced that, now I can work for any of several shops instead of having to work X classes at one to be on the umbrella policy.

By doing that I moved from all diving income is gravy to all diving income is trying to cover costs....

Plus...well Chris and Chrissy paid dearly for being broke, but it was their right to decide...IMHO..

Unless somthing happened Marty and Marc were there for training... You had to have seen them, but they were only there Saturday as I recall. Marty was the guy sitting to my right at the Forum Thursday...

James

I pay for my insurance independently as well. Need to be covered for my occasional stints as a Cave Class DM, and I also end up working as a DM once in a while at remote dive sites where I show up without a buddy and find a class before I can find a buddy. Free DMs willing to work are always welcome!

Have you read "The Last Dive"? Chris and Chrissy were more than just broke. They were also foolish, lax with safety procedures, and desperate to make a name for themselves by making a discovery. Deep air narcosis may have put the lid on their coffins, but they put themselves into those coffins.

theskull

[theskull]

TS,

Are you planning on bringing any kind of recording eqipment with you when you dive the AD? Yea we've all seen the shows but a local experience just brings those of us who have no desire to hassle with the proper training and eqipment that much closer...

James

My camera isn't rated to that depth. :)

But I will take surface photos and buy, beg, or borrow uw photos taken by my cruise-mates. Might even show them around when I get back. ;)

theskull

[Atlaua]

Have you read "The Last Dive"? Chris and Chrissy were more than just broke. They were also foolish, lax with safety procedures, and desperate to make a name for themselves by making a discovery. Deep air narcosis may have put the lid on their coffins, but they put themselves into those coffins.

theskull

I've read both accounts...and I'd love to know the truth about who made the chopper wait, but I doubt I ever will. Yea they made some really deadly (I won;t call them stupid because that would be speaking ill of the dead) mistakes, but to me I always see it as a $$$ factor....

They died because business was down... The rest was just part of the chain...death rarly happen because 1 thing went wrong. It's usually a chain....but the first link in the chain is the one you have to blame and the first link for them was.....being too broke for trimix an diving anyway...

James

[jclifton]

TS,

I was out at Padi's site and it's interesting that they only have one Trimix class rather than a Normoxic and Hypoxic seperation. Just something that seemed interesting.

Great to hear about your class. I hope someday soon to be able to take it also. I do have a question though, where could you possibly hang four stages?

Jason

[Atlaua]

I do have a question though, where could you possibly hang four stages?

Jason

Two on each side... Clipped off on the shoulder strapp and waist. I've never ddone a "real" dive this way but I'be done it in the pool, not as bad as it sounds...

James

[SLIM]

You can hang all 4 on the left side. There are many ways that you can handle your stages. It takes time and practice. I wish I could have seen how TS improved from the last time I saw you cary 3 for the first time.

The taks loading is greatly enhanced and to remember all the dive plan for everything gets to be taksing.

A RB is another tool. like TS said, you have to have the amount of gas for bailout of your planned deco. So many do not cary it. It is nice on a long charter when you can have your bailout and use it all 2-3 days for all the dives you might do and you only have to re pack your RB once. THe training for a RB is very extinsive if you are going ot use any besides a recreationnal RB and the mantinace and upkeep is incredable. After TS takes this class he will have passed me in my mix diving classes. I cheated, took normaoxic but still do trimix dives.

Boy one trip I wish I could make it on with him.

TS you will have passed me after you do the AD. Just give me time, I will get there.

SLIM

[theskull]

TS,

I was out at Padi's site and it's interesting that they only have one Trimix class rather than a Normoxic and Hypoxic seperation. Just something that seemed interesting.

Great to hear about your class. I hope someday soon to be able to take it also. I do have a question though, where could you possibly hang four stages?

Jason

Not as different as it sounds. In TecDeep PADI chooses the dangers of deep air and narcosis over the dangers of helium and it's required deep stops and slower ascents. Also saves the expense of helium during the first part of the course. Then in Tec Trimix the first few dives are done on Normoxic Trimix and then you progress to Hypoxic over the duration of the dives done.

As has already been answered, there are several ways to carry 4 stages. I chose to leave my LP steel O2 on the right side and put the 3 aluminum bottles on the left side.

theskull

[theskull]

. . . After TS takes this class he will have passed me in my mix diving classes. I cheated, took normaoxic but still do trimix dives.

Boy one trip I wish I could make it on with him.

TS you will have passed me after you do the AD. Just give me time, I will get there.

SLIM

1. I was more than willing to cheat, too, but the charter required the card to board the boat. I'm just counting it as part of the price of the trip.

2. I wish you were coming, too. Know that it is because of all the diving I've done with you that I now have the confidence to make a dive like this with a just-met buddy on the boat.

3. Passed you? I think not! You've already been deeper than I ever plan to go. I could elaborate further, but don't want to assault your modesty.

theskull (grateful to all my mentors and instructors, but especially to you!)

[reefraff]

As a Full Trimix Diver I will be "qualified" to dive to any depth with any appropriate gas mix. Are there really no depth limits to the PADI Trimix certification?

[Atlaua]

Are there really no depth limits to the PADI Trimix certification?


Wow you can't get much more loaded than that question! Good point though...I'm sure the real depths will follow...

[theskull]

Are there really no depth limits to the PADI Trimix certification?

Really.

In the usual PADI fashion, and I believe well-reasoned, the line is that on certification you are qualified to dive to 245 feet or to the depth of your deepest training dive, whichever is shallower.

Then you are to extend your limits slowly through gradually more challenging dives and diving with more experienced buddies.

But there are no depth limits or mix limits to the cert.

theskull

[reefraff]

Really.

In the usual PADI fashion, and I believe well-reasoned, the line is that on certification you are qualified to dive to 245 feet or to the depth of your deepest training dive, whichever is shallower.

Then you are to extend your limits slowly through gradually more challenging dives and diving with more experienced buddies.

But there are no depth limits or mix limits to the cert.

theskullI wasn't intending it as a trick question - I'm just surprised that PADI would accept exposure to the wrath of the family of the guy who decides no limits means no limits. Depth limits are like speed limits: always advisory and some of them, like the 60 foot limit for new PADI divers, are routinely...challenged.

My TDI card has a 100 meter limit printed on it, something I've always looked at a a reminder that I'm an idiot and to be sure to think twice before doing what I'm going to do anyway. Most people would define a dive to 330 feet as bad craziness, would anyone be surprised to hear that those of us willing to deal with the risk, time, and cost of that kind of foolishness might actually push a little deeper? :D

[ppo2_diver]

Like it was said before, there are many ways to secure your stage/deco bottles. If I'm diving 4 or more bottles, I clip two AL40's on the left like normal. I then have a leash that is about 6 inches long with a bolt snap. I snap the leash to my left hip d-ring and top clip the remaining bottles on the leash. The WKPP uses something similiar, but they have a ring attached to the leash to top clip the bottles to. I don't know if they have changed this or process or not.

Now if I'm only diving 3 bottles, I'll secure two on the left like normal and then top clip the third bottle to the left hip d-ring.

[DeepDiverBob]

Accroding to the PADI DSAT, the do leave it a little open eneded. They state the "braod community standard" is anthing below 165 is trimix. I will quote them here for the rest...

" While there's a fairly strong consensus (within a range) regarding the maximum depth you can go without trimix, there's no real basis for a maximum depth with trimix so far.

The typical range for new, beginner trimix divers is to 245 feet, or the maximum depth you experienced during training.

Experienced trimix divers sometimes dive as deep as 30 feet.

Divers between 300 feet and 400 feet are not unusual for very expereiced (leading edge) trimix divers

The maximum training depth for the Tec Trimix Diver course is 245 feet, thought the deepest depth you train in might be less depending upon your local envirenment..."

Again, sounds pretty open ended to me, too.

[theskull]

The Dives (cont.)

Glad to see so much interest in this topic. I know some of you do these dives, and some of you are just curious. For the slightly more than curious I'd like to add that tech diving is not and should not be something everyone aspires to. In addition to the awesome expense of gear, training classes, gear, travel, gear, and expensive gases to breathe, there is a necessary commitment to dive quite often to maintain the sharp skills and safety habits that make the risk tolerable. There is not much margin for error allowed on deep dives or dives in an overhead environment, and small mistakes can set a deadly chain of events in motion. Those of us who do it have a passion for seeing some things that just happen to be beyond the scope of recreational diving. Those who don't do it have a lot more time and money that can be spent on travel to exciting and exotic locations where the diving is less hazardous yet thrilling in other ways.

Today's dives, which were made on Trimix with EAN deco gases, included drills designed to simulate some of these problems and averting or managing the problem before it becomes an emergency. Those included:

Buddy swims off in a different direction without first signalling intent
Deploying a lift bag from depth to create an ascent line/marker buoy
Buddy runs out of gas at max depth while you are working the reel
Buddy ascends past a planned deco stop
Buddy is using different deco gases than you are
Holding deco stops midwater without an ascent line
And a couple more out of gas scenarios

Weather and circumstances permitting, we will continue next weekend with Hypoxic Trimix as our backgas for the next few dives.

theskull

[jclifton]

I for one have been following this thread with interest. For me, hopefully, one day my skills, money and schedule will allow me to take this class. The class exercises and equipment requirements are interesting. Requirements such as four stages become interesting mental exercises, you know where the crap could you possibly hang those bottles and still be able to swim. In real life adding one stage bottle was more task loading than I had given it credit.

Now the whole discussion of a person’s personnel evaluation and contemplation of technical diving is a whole forum/thread in itself.

Jason

[do it easy]

I like this thread. What happens if your buddy is using a different deco gas? You would have different schedules, so do you just get above or below them and hope to meet up at 20' or is there some protocol for "gas/profile matching" or buddy breathing?

[ppo2_diver]

Nobody on the dive team should be diving different gasses. Everyone on the team dives the same gas (bottom mix and deco). That way the team descends together, completes the mission, ascends together and does deco together. There is a lot of togetherness in tech diving. :)

[theskull]

Nobody on the dive team should be diving different gasses. Everyone on the team dives the same gas (bottom mix and deco). That way the team descends together, completes the mission, ascends together and does deco together. There is a lot of togetherness in tech diving. :)

Certainly that is the ideal situation. And I know that there are some divers who would skip the dive or exclude a buddy if the match was not perfect.

But in the real world, with buddies who don't have an unlimited number of tanks laying around, or who we may meet at the dive site without knowing they were going to be there, many of us will make allowances and still do the dive.

A simple example would be one buddy only has EAN 50 and one only has O2 for a deco gas. You have choices to make:
1. Skip the dive.
2. Dive solo.
3. Separate at the 70 ft. stop and make solo deco stops.
4. Dive the O2 deco profile, but the diver with EAN 50 makes his gas switch at 70 ft.--probably will be pretty close to even once the O2 diver makes his gas switch at 20 ft., but someone will be staying in the water a little longer than he needed to.
5. Plan a dive having only a 20 ft. gas switch to EAN 50, and the O2 diver will be in the water longer than he needed to.

You would have similar choices to make for a planned dive to 150 ft. with one diver diving on air and the other using TMX 20/30.

Among the choices we make in diving are who we are willing to make a given dive with and whether we believe a dive can be safely executed even though the variables are not all perfect.

I'm not giving THE answer to any questions here, and don't personally believe there is ONE single answer. Just listing some of the options and considerations with which I have dealt on dive sites, and some of the answers with which I am comfortable.

theskull

[reefraff]

Certainly that is the ideal situation. And I know that there are some divers who would skip the dive or exclude a buddy if the match was not perfect.Though I'm an occasional solo diver, never when it comes to decompression diving. Maybe its a comfort level thing but there is a lot going on during decompression and I like having a buddy there who is on the same page I am, literally, to back me up. Planning and using standardized gases (instead of blending for optimal) means not having to worry about somebody showing up with 25/28 for backgas and pretty much eliminates this kind of confusion.

It's been my experience that most problems come up at the gas switches, when the task loading is greatest. Hypothetically, if the plan is for 30 minutes BT at 150' and one diver is using 21/35 and the other is using 18/45, I would make the dive but both divers are going to follow the (more conservative) 18/45 table. If the only way to get the dive done is to use different deco gases and follow different schedules then what we're really planning is to be SOBs. For me, at least, that means there isn't a way to get the dive done. The deeper you go and/or the longer you stay, the more important it becomes to synchronize plans, gear and attitudes.

You're right, however, others can and do things differently. Just one more sign that the Universe can be a strange and scary place. ;)

[theskull]

The Dives (cont.)

We're back at Oronogo with a couple sets of doubles filled with Hypoxic Trimix for the remainder of our dives. Also refilled the EAN 50 and O2 bottles and topped off the Argon cylinder for suit inflation.

Today's dives had us performing most of the skills at max depth, including:
Simulated regulator free-flow and valve shut down
Simulated stuck inflator valve
Deploy lift bag, lift bag fails, deploy 2nd lift bag up the same line

Shallow water skills performed at deco stops included:
Simulated stuck drysuit inflator
Simulated unintended ascent to surface during deco stop and recalculation of required deco obligation to compensate for problem

These dives and the remaining ones for the course are mainly about doing the dives. They are enjoyable relaxing deep dives with the skills sprinkled in at comfortable intervals. This is partly an acknowledgment of the real danger involved in experiencing problems at these depths, and partly recognition that someone who enrolled in this course properly prepared and made it this far into the course with the instructor's supervision and approval shouldn't be making many mistakes.

Also took and passed the 50 question written test today during the surface interval. In my opinion, the DSAT Trimix textbook is very well-written and well presented. And, the test was relevant and fair.

Just finished preparing the deco schedules and contingency schedules for tomorrow's planned dives.

Now for some relaxation and nice quiet night.

(to be continued)

[theskull]

The Dives (cont.) -- Final Episode

We made our final dives for the certification adventure today.

The only required skills for the dives today were to plan and execute the dives and be prepared for any surprise problems the instructor might care to throw in for fun. I did end up performing some skills as a buddy since we were joined today by another student who is at an early point in his dive sequence for the course. So I got to brief my buddy as to the deco schedules I had planned and signal him during the dive to confirm depth changes and gas switches. Also during the shallow part of the dive at the beginning I participated in out-of-gas drills with my buddy.

As a bonus, after completing our first dive, we were exiting the water onto a "barge" (floating dock with tow motor), and while shuffling gear onto the barge my O2 bottle slipped over the side and plunged to the bottom. The bonus was I got to begin our final dive with a giant stride entry off the barge with deco bottle in place, and on initial descent we got to make a search-and-recovery dive for my O2 bottle in 160 ft. of murky green water. I was the one who found it, and fortunately it had landed in a nice soft pile of silt--not a scratch.

This was a very enjoyable course to take. My instructor is a very experienced deep diver, with credentials including many deep wreck dives, commercial diving and military UDT diving. The course is well designed, both in the excellent written materials and in the relevant skills that are thoroughly taught and tested. I hope anyone who takes this adventure gets as enjoyable and rewarding an experience as did I.

theskull