Deco with too less air, options from the book

[Chatterton]

BJ,

I don't get it? I must be out of touch...... agian.

I don't think I have to apologize to the rest of the world, but I am with you. I love dive computers. What is not to love? They have come a long way from the ScubaPro Deco Meter, but to tell the truth I even liked that thing?

I will generally use one computer and a depth gauge/timer with a table in my pocket, or two computers (and probably still carry a table) on a serious dive. For comparison on Britannic, it was the Vision electoronics, a VR3, and a table.

By the way, I somethimes have to lie to my computers to get us all on the same page, but that is another thread probably?

My new favorites are the Shearwater, and the VRx, for a bunch of reasons. I don't like crap computers, or crap anything else in diving for that matter?

If somebody does not want to dive a computer, then please go with what works for you, but computers work for me.

Do I get flamed, tarred and feathered now? Can I share some flame and tar with you as well?


Cheers

JC

That was not directed at you.

It was an observation of the atmosphere here on SB. Every time I have every seen anyone advocate computers for deco, it has sparked that negative reaction. The one exception is when I saw you make a similar observation in a past thread, and again there was no such response.

I myself do not have those feelings. I am only now taking advanced deco, but my tech instructor fairly spits when talking about computers, and you can be sure we will not be using them throughout any of my training.

 

[Chatterton]

Pete,

Get a second computer, forget Ratio Deco, and use desktop software to make modern tables as a backup.

Do not get on the bus to hell. It is an express, and you will know a lot of people already there.


CHeers

JC

John, you may have missed this part:

<<I don't dive Navy tables as a standard practice, but I have a copy on me for all deco dives. If things go real south - lost computer, lost buddy, lost anchor line, I still have a timer and depth gage and a set of tables.>>


Like I said, I don't dive them but I do carry a set for the event I get handed a ticket to hell and need to get off that bus.

I will also use them as a touch stone to check a computer generated or Ratio Deco schedule. If they are less then Navy Tables or close to them, I will check very closly to find out where the error is. Because there is an error if a modern table is getting me near Navy stops.

I also wanted to point out to anyone that there is a range in the Navy table where you have to very carfull due to the required deco obligations.

Give me a call when you are passing through or have time to get wet up your way. I still have those videos from to English Channel to show you.

 

[boulderjohn]

Do I get flamed, tarred and feathered now? Can I share some flame and tar with you as well?

JC

My guess is that you'll get a pass. I think it's too bad, actually. Not that I want you to get flamed, but I think I would learn something from an intelligent exchange on the topic.

 

[TSandM]

Well, a lot of the people who inveigh against computers are actually discouraging the practice of jumping in the water with little forethought, and doing whatever the computer says you ought to do. Somehow, I seriously doubt that Mr. Chatterton has EVER done a staged decompression dive that wasn't preplanned, with a proposed profile and gas supplies and decompression worked out ahead of time, and then the computer used as a crosscheck as the dive actually unfolds.

I have to admit, even as a fairly committed member of the "computers rot your brain" crowd, that I have trouble understanding what is heinous about using VPM software to cut tables for a dive, and then using a wrist computer that is running PRECISELY the same program to monitor the dive as it progresses. Although the folks that trained me aren't cutting VPM tables, either . . .

 

[dumpsterDiver]

I sometiemes will do 5 or 6 dives per day on nitrox in the 90 to 130 ft range and will go into required decompression on 2-3 of those dives, but the deco time will typically be less than 6 minutes. I never look at tables or a software and rely upon my one (single -gas) computer. After doing this kind of diving for a long time, you kinda know when you are approaching the deco limits.

We are unable to plan our depths and times, since we are spearfishing and driving around and just dive at whatever depth (within a range of course) that we see fish on the recorder. If there are few fish when we get to the bottom we come up soon, if there are a lot of fish, our dives will be longer.

Running tables or software would use a lot of valuable time and is impractical for us. I see no problem with following a computer as long as you don't do something really off the wall. (we also cheat on the computer and do some oxygen deco when we can). I also add my own deep stop, even when the computer doesn't like it.

We don't follow the computer blindly, but I DO rely upon it to keep me out of trouble and it is a valuable tool.

 

[MXGratefulDiver]

I had to ask Howard if I was allowed to make 5 posts in a row? He told me I could, but I still feel a little crazy about it. Anyway, blame him.

Try using the M-quote button instead of replying to individual posts ... it lets you reply to multiple posts with a single reply ... like this ...

I have always loved Run Time, and never use anything else when making a table!!! You can refer to the table at any time and always know where you are supposed to be. Some times it can be a little confusing trying to do math on the hang, especially with a lot of stops. The only thing I love more is a good dive computer that gives me a cieling instead of stops.

I will now be quiet. Thanks for your patience.


Cheers

JC

What a wonderful thing a reputation is!

If one of the "regular" thousands of SB members with a typical (lack of) reputation had written that sentence, there would be 5 pages of "You ignorant ****!" posts within 24 hours.

Why? I happen to agree with him ... and in fact my Liquivision X-1 does exactly as he describes ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

What a wonderful thing a reputation is!

If one of the "regular" thousands of SB members with a typical (lack of) reputation had written that sentence, there would be 5 pages of "You ignorant ****!" posts within 24 hours.

Hey, I have to call em as I see em. Feel free to call me an Ignorant *****, as you wish. You will not be the first, or the last?

Actually, I am not even sure what I said that is "bad"? Is it using a computer, or using ceilings?

CHeers

JC

That was not directed at you.

It was an observation of the atmosphere here on SB. Every time I have every seen anyone advocate computers for deco, it has sparked that negative reaction. The one exception is when I saw you make a similar observation in a past thread, and again there was no such response.

I myself do not have those feelings. I am only now taking advanced deco, but my tech instructor fairly spits when talking about computers, and you can be sure we will not be using them throughout any of my training.

There's a HUGE difference between using a computer and relying on one ... especially for doing deco. Most tech instructors won't let you use a dive computer during class because they don't want you to learn deco by relying on one. Most tech divers I know frankly don't care whether you use one or not, as long as you don't use it to determine your deco schedule.

Recreational diving is another bailiwick altogether, and almost any dive computer will get you out of the water safely every time ... although to my concern it's still important to understand the data the computer provides, and recognize that the computer doesn't know a damn thing about you ... that the numbers represent some theoretical "ideal" diver.

The problem most SBers who object to computers have with them is that people tend to turn off their brain when they turn on their computer. The two should not be mutually exclusive. A dive computer is simply a tool ... whether it's a good or bad thing depends entirely on how you use it.

Pete,

Get a second computer, forget Ratio Deco, and use desktop software to make modern tables as a backup.

Do not get on the bus to hell. It is an express, and you will know a lot of people already there.


CHeers

JC

Just as the computer, people who use Ratio Deco need to understand what it is and under what conditions they should use it. It's not a deco algorithm ... it's simply a profile-shaping tool. If you don't understand the assumptions and limitations of the tool, then certainly you shouldn't use it.

But the same goes for dive computers. Getting a second computer will only help if you understand it enough to use it properly.

... Bob (Grateful Diver)

 

[Chatterton]

We all don't have the same goals with our diving, dive the same gases, or use the same equipment. The dive computer is just another tool, and its strength is that it can address a wide specrum of needs.

Most of what I know about decompression and technical diving, I have learned from using desktop software to generate dives in the comfort of my home, and then watching my dive computer on real dives.

The dive computer is a powerful tool, but it is not a substitute for experience, planning, education or intellignece.

Cheers

JC

 

[Chatterton]

This from Dick Vann the head research Guru at DAN: Sorry I still can't do the MQuote thing yet?

Hi John,

Yes, indeed. This is known as acclimatization or adaptation to decompression. The literature is not extensive, but I reviewed what is available on pgs 138-139 in Chapt 7 of BoveÃÔ 2004 (4th ed) Diving Medicine text. Work up dives seem to be very helpful in reducing DCS risk.


Happy New Year,


Dick



From: John Chatterton [mailto:jc@johnchatterton.com]
Sent: Monday, January 12, 2009 9:24 AM
To: Denoble, Petar; Vann, Richard
Subject: Ramp up dives


Gentlemen,

I hope all is well with the both of you guys these days.

I have a decompression question? I have come to believe that prior to a big deep dive such as Britannic, divers benefit from ramp up dives? These are defined as dives to promote good off and on gassing conditioning. This would be opposed to not diving for a couple of weeks prior to the Big Dive. Are you aware of any research that might support, or refute this??



Cheers

JC

Mr Chatterton,

What is the data to support the concept that nitrogen loading and unloading changes with the frequency of diving? This is not intuitively obvious to me and may run counter to physiologic principles.

Thanks, and good diving, Craig

 

[seaducer]

This from Dick Vann the head research Guru at DAN: Sorry I still can't do the MQuote thing yet?

Hi John,

Yes, indeed. This is known as acclimatization or adaptation to decompression. The literature is not extensive, but I reviewed what is available on pgs 138-139 in Chapt 7 of BoveÃÔ 2004 (4th ed) Diving Medicine text. Work up dives seem to be very helpful in reducing DCS risk.

I heard a hypothosis a while back that sounds exactly like this. Basically your tissue gets more efficient at ongassing and offgassing the more it has to. Sort of like muscles become more efficient at burning oxygen and glucose during exercise and are more efficient at removing lactic acid the more you work out.

It is nice to see there may be some actual evidence to back this up.

Im just a shallow no stop guy, but when on vacation this has some merit as I am doing a lot of multilevel repetative dives.

And it also allows an excuse to the Mrs. as to why I HAVE to go diving more often!