Computers

[And]

<font color='#0000FF'>Hi

Originally Posted by [b

Quote[/b] ]I recently looked at two dive profiles and immediatly thaught, they dont look right. On further alalisis I couldent even get the most adventurous modle to accepth the profile. Both divers who did the dive got bent. They got bent because they didnt fulley understand what they were doing and they had no computer to warn them of their error.

In your opinion that is how they suffered DCI. IMO they got DCI because they did two aggressive dives in one day. There were other divers on the initial dive who didn't get DCI. I believe they are in fact TDI trained Mark, the same as you, although they dive with DIS-UK.

IMO it is only a matter of time before you start to ignore the tables and simply trust the computer, after all both yourself and AndyP have said that the VR3 gets you out quicker, and you favour that. IMO I can see that you will end up planning gas using tables (more conservative) and run the deco on the VR3. If the VR3 breaks, go to tables. Again, no one is saying you will die or that is wrong but it is not the intention of DIR to plan dives that way and that is the debate. We can all pick out individual cases were divers get it wrong but I feel that detracts from the point.

As Mike Kane stated, DIR aims to make decompression more efficient and more effective. The Buhlmann model is a bend and mend model and it was work done by Bruce Wienke I believe which introduced the Gradient Factors which when applied introduce deep stops. The new version of Decoplanner will use the RGBM/VPM model. Even this new model is not going to be perfect. With any model it is based on assumptions and is therefore flawed and is a 'best guess'.

Originally Posted by [b

Quote[/b] ]However. the piece of kit he is really attacking, very cleverly I admit, is the VR3. It has to be said, I am the eternal skeptic with this bit of kit, but I am going to get myself one. It offers the advantage of real time up date of your dive profile, uses a modified buhlman table and gives deco profiles very similar to the tables I run off prior to each dive. It allows for the fact that although I have planned for a 65M dive my actual depth was probably 57M, this gives a reasonable saving in deco when bottom times are 40 mins. With a deco commitment of well over an hour, 5 mins can seem like an eternity, if it is possible to save this then I for one will take it thank you very much. Having said this, only a raving maniac would rely exclusivly on a single piece of kit, which is why all the people I know who dive a VR3 also carry a dive timer of some sort as well as tables and bail out profiles.

This was a post on scubaboard, a recreational divers site. The technical spinoff is thedecostop. If Mike was attacking the VR3 he would have posted on that site surely? The VR3 is only just making its way to the states and in the meantime Abyss has had a multigas computer for a while.You are seeing it as an attack on the VR3 simply because this purchase is uppermost in your mind at the moment and you see this as criticism of your decision. Its not.

My own belief after reading and digesting and asking questions and then reading again is that when you use tables printed from a computer you are still relying on the computer. When you use the wrist computer its just delivering tables on a pretty screen. To understand how your body ongasses and offgasses and then how to 'know' the best way to decompress is the aim. No matter what happens during the dive I want to be able to know what to do, deeper, shallower, longer, shorter, lost gas etc. I think its training and learning which buys that knowledge, not a £1000 ish wrist computer

Andy

[Mark Chase]

Originally Posted by [b

Quote[/b] (Mark @ Sep. 06 2003,11:36)]

Originally Posted by [b

Quote[/b] ]As I have said before, DecoPlanner does not produce DIR deco schedules straight out of the box. You need to know how to shape a deco curve and modify what it produces. You can happily dive the standard profiles (as you do) but they are not DIR and don't claim to be.

Do I?
How do you know?

For your future information I dont think I have ever dived a standard profile on tables or on a computer. Also what is the standard profile on Decoplanner? Because I dont know. There are so many vairiables. I will usualy plan a dive on 10-80gf or 20-85gf using 20m/min decent &nbsp;decent imediate using the ZLH16/b model. As a start point.

Decoplanner is designed and writen by GUE. Are you sugesting that ony the in house DIR boys have the seceret coads to use it safley and that all non DIR users will get bent on it?

Originally Posted by [b

Quote[/b] ]If your max depth was 65m then you blew your deep stop if you did it at 42m. &nbsp;

Not according to Decoplanner set to 20-80 and 10-80 first stop depth is 42m. If you set the GFlo to 5% (thats as low as you can go) it is still 42m. So below that depth you are not off gassing at all you are on gassing. Stops below 42m are detremental to deco on this dive. The VR3 will control bubble formation to 42m using a slow ascent rate.

Originally Posted by [b

Quote[/b] ]

Oh yes it is........ It does not encourage you to use your brain or learn. In fact it is probably designed to fool you into thinking that deco is a super-technical-science that needs a fancy bit of hardware to work out for you (££kerr-ching££).

Unless you plan all your dives using base principles you are talking nonsence. The vast majority of divers will use Decoplanner, Proplanner, Z planner etc. or hard tables to paln a dive. Why are these systems any less of a no brainer than a dive computer? Hands up all the divers who analise the graphs or compartment presure info after cutting the table. Very few I think.

People who dive computers with no understanding of the information the computer gives out are no brainers and the same divers using deco softwhere on the computer at home without understanding the data and cutting tables are equaly no brainers. But who can blaim them. If they dive for fun and use a computer or tables week in and week out without getting bent then just sit back and enjoy the dive. It is not my personal choice but I find it dificult to be too critical of those that do.

Originally Posted by [b

Quote[/b] ]They were not GUE trained actually. They did screw up a little in the deco but more importantly with what they did after the dive. They did post dive activities which are supposed to be avoided.

OK so what you are saying is that these divers folowing the path of DIR cut their own tables, modified them them selves and dived on a depth and bottom timer and got bent. I say had they had a VR3 on their wrist they would have had it screaming a warning at them.

They did screw up a little? &nbsp;they missed 72mins of stops diving a 20-80 profile and over 40mins of stops diving a 20-100 profile over two dives in one day. I would say they screwd up big time and then put in print that their profiles were OK. OK for what?

I am sure the post dive activitys added to the problem but not much.

If thats not enough run the other profile of the 60m dive with the two divers getting bent. I ran the print out from their Viper through decoplanner and they missed a shead load of stops too. They did about 18mins of stops between 12 and 6m inclusive and decoplanner came up with 31mins of stops for their profile.

Another mystery bend solved

Sorry it is NOT safer diving tabls than diving a computer. It is just as dangerous if you dont know what you are doing. The above facts speak for them selves. Diving tables and a computermust surley be tha best of both worlds. The tables give a point of referance and the computer maps the actual dive profile. Then your brain pads out the stops to take account of conditions your personal state etc.

If I have had a bit of a streneous dive or things went wrong before or during the dive I will always add on time to the shallow stops and breath 02 on the boat but i am always adding to the planned profile. I have never taken an already agresive profile and thaught I know Ill shave some stop time off because I know more than mr Buhllman. I find it no surprise at all that regularly when you examin the profiles of divers who got bent but claim to have followed the profile exactly, either A: they didnt folow the profile or B: the profile was wrong.

No one will ever convince me that computers are a bad thing in diving only that some people dont know how to use them properly.

ATB

Mark Chase

[Mark Chase]

Originally Posted by [b

Quote[/b] (wetlettuce @ Sep. 06 2003,13:36)]

Originally Posted by [b

Quote[/b] ]Hi

In your opinion that is how they suffered DCI. IMO they got DCI because they did two aggressive dives in one day. There were other divers on the initial dive who didn't get DCI. I believe they are in fact TDI trained Mark, the same as you, although they dive with DIS-UK.

I dont care who trained them they screwd up their tables. I asumed DIR because they were posting on a DIS-UK web site

OK Andy thats it: Put your money where your mouth is. I spent a lot of time analising their profiles and couldent get them within accepted safe working peramiters. You say I am wrong and that is not the reasion they got bent.

So come on Andy justifie their profiles. Show me a graph using tisue compartments 1 -16 and M-values that make their profile work. Use what ever table you like but I am most familier with ZLH16 using Ambient presure in MSW absolute. any thing else will take me a bit of time to follow but thats OK I will figure it out. To keep things simple you can use the fasted the middle and the slowest compartments only to plot the graph.

This should be interesting

Originally Posted by [b

Quote[/b] ]IMO it is only a matter of time before you start to ignore the tables and simply trust the computer, after all both yourself and AndyP have said that the VR3 gets you out quicker, and you favour that. IMO I can see that you will end up planning gas using tables (more conservative) and run the deco on the VR3. If the VR3 breaks, go to tables

I will never ignore the tables and I will have a prety good modle of the deco from memory before every dive and the table on a arm slate right next to the computer screen. So glance at screen glance at tables at the same time. Its a multy slate so I flip to the required profile. Yes we will run deco on the VR3 whilst compairing it to tables and making a choice based on our knoladge at every stop.

Originally Posted by [b

Quote[/b] ]The new version of Decoplanner will use the RGBM/VPM model. Even this new model is not going to be perfect. With any model it is based on assumptions and is therefore flawed and is a 'best guess'.

As I said the VR3 is upgradable with the latest softwhere as soon as it hits the market. You can down load it streight on to the dive computer from the internet.

Originally Posted by [b

Quote[/b] ]My own belief after reading and digesting and asking questions and then reading again is that when you use tables printed from a computer you are still relying on the computer. When you use the wrist computer its just delivering tables on a pretty screen. To understand how your body ongasses and offgasses and then how to 'know' the best way to decompress is the aim. No matter what happens during the dive I want to be able to know what to do, deeper, shallower, longer, shorter, lost gas etc. I think its training and learning which buys that knowledge, not a £1000 ish wrist computer

The VR3 in full trimix mode is available for £680-£700. The computer will instantly calculate all of the situations you have described above. You can also switch to a gas mix that was not planned for the dive and re program the computer under water and it will recompute your deco on the new gas. Someone without a great depth of knoladge stands a chance of getting out of the water with a VR3 in the above situations. Smeone who has not got the abuility to mentaly compute deco on the fly and only has fixed gas tables is going to be in trouble. Remember with the VR3 even if you violate all the info it gives you it will attempt to compute a best guess to get you out of the water it will not just revert to gauge mode.

ATB

Mark Chase

[Tibbs]

Originally Posted by [b

Quote[/b] (Mark Chase @ Sep. 06 2003,15:01)]OK so what you are saying is that these divers folowing the path of DIR cut their own tables, modified them them selves and dived on a depth and bottom timer and got bent. I say had they had a VR3 on their wrist they would have had it screaming a warning at them.

They didn't modify themselves - they asked John Grogan what he'd do and then copied it. John Grogan is the unbendable man. I'd heard of him and his profiles long before I'd heard of DIR!

Chris

[And]

Originally Posted by [b

Quote[/b] (Mark Chase @ Sep. 06 2003,15:30)]OK Andy thats it: Put your money where your mouth is. I spent a lot of time analising their profiles and couldent get them within accepted safe working peramiters. You say I am wrong and that is not the reasion they got bent.

So come on Andy justifie their profiles. Show me a graph using tisue compartments 1 -16 and M-values that make their profile work. Use what ever table you like but I am most familier with ZLH16 using Ambient presure in MSW absolute. any thing else will take me a bit of time to follow but thats OK I will figure it out. To keep things simple you can use the fasted the middle and the slowest compartments only to plot the graph.

This should be interesting

<font color='#0000FF'>Hi Mark

Perhaps you should read the title of the thread again. DIR and computers. It seems each topic recently you bring this up. I shall if you wish find reports of people who suffer DCI whilst obeying their computer. Will that progress this discussion constructively ?

You are saying the accident/incident happened because they didn't have a computer, I am saying that others used the same profile and did not suffer DCI. I can create a similar profile by using 20-130 GF's but the curve is slightly different. The divers concerned had a second similar dive on the same day and suffered DCI. Was that because of the first dive or the second? Who knows for sure? I haven't said that the profile is right or wrong because the 'profile' is just a mathematical model. &nbsp;The only way the model was created was by chucking people in the water and seeing if they suffered DCI. If they did then the limit was lowered. The US Navy tables even built in a DCI probability meaning that it was acceptable for 20% of their divers to suffer DCI. Hardly accurate or even relevant to our own particular physiology.

Decompression as you know is not an exact science and some will get DCI even on the most conservative of profiles, there is a thread about that 'Call me Bender' or something in the medical forum. I know someone myself who obeyed the computer but suffered DCI but he was overweight and a smoker. How does the mathematical model compensate for that. It doesn't so the diver has to.

Other people will be able to walk from the water with no symptoms on the most aggressive of profiles. Learning how to adjust the deco curve to suit your own limits is part of DIR.

Just these facts alone make me think that I need to know a little more about what I am doing and not just follow a mathematical equation.

I am happy to justify why DIR believe that computers are not needed but I shall not justify someone elses dive plan as I was not party to the discussion or to the advice they were given. Lets keep it on topic Mark and move on.

Andy

[JohnD]

<font color='#F52887'>I do not pretend to be at all DIR, (i am of the, do thing the way you have worked out to be right for you way of thinking) I do like to hear from anybody why they do things the way they do it. I recently did a couple of TDI courses and liked the &quot;techie&quot; mindset about planning dive on paper and diving the plan, in both gasplanning and deco. From that point onwards I have dive with table I have laminated and I plan the dive with backup plans too (usually 5 different alternates including without either deco gases) I have my Cobra set to guage mode unless I am doing with my missus using singles, but I still wear a 3-layer clear slate with lanimated deco tables in the pockets, check it out, made by Bowstone.

[Mark]

<font color='#000080'>

Originally Posted by [b

Quote[/b] ]Do I?
How do you know?

For your future information I dont think I have ever dived a standard profile on tables or on a computer.

I deduced from some of your previous posts that you play with the GFs. That's fair enough. But do you play with the actual generated tables at all? That's what I'm talking about.

Originally Posted by [b

Quote[/b] ]Also what is the standard profile on Decoplanner? Because I dont know. There are so many vairiables.

It's up to you. 30/90 is good and so is 20/85.

Originally Posted by [b

Quote[/b] ]Decoplanner is designed and writen by GUE. Are you sugesting that ony the in house DIR boys have the seceret coads to use it safley and that all non DIR users will get bent on it?

Er no, not at all. What I mean is that with the proper training you can produce a more efficient deco curve/profile than ANY software can produce on its own (including DecoPlanner). It works fine just as it is though. I occasionally use DPlan on a PDA myself.

Originally Posted by [b

Quote[/b] ]

OK so what you are saying is that these divers folowing the path of DIR cut their own tables, modified them them selves and dived on a depth and bottom timer and got bent. I say had they had a VR3 on their wrist they would have had it screaming a warning at them.

They did screw up a little?  they missed 72mins of stops diving a 20-80 profile and over 40mins of stops diving a 20-100 profile over two dives in one day. I would say they screwd up big time and then put in print that their profiles were OK. OK for what?

I am sure the post dive activitys added to the problem but not much.

I was talking about another incident - This one. Hence the confusion. I do recall the one you are talking about though.

Originally Posted by [b

Quote[/b] ]Sorry it is NOT safer diving tabls than diving a computer. It is just as dangerous if you dont know what you are doing. The above facts speak for them selves. Diving tables and a computermust surley be tha best of both worlds. The tables give a point of referance and the computer maps the actual dive profile. Then your brain pads out the stops to take account of conditions your personal state etc.

The point you are missing is that thanks to my training with GUE I don't think your tables and computer combination is the best of both worlds. You just think it is because you have not been shown a better way of doing it. No problem, just don't rule out the possibility that you may be wrong.


Regards,

Mark.



PS. Deep Stops

[Mark Chase]

Originally Posted by [b

Quote[/b] (Mark @ Sep. 06 2003,19:09)]

Originally Posted by [b

Quote[/b] ]I deduced from some of your previous posts that you play with the GFs. That's fair enough. But do you play with the actual generated tables at all? That's what I'm talking about.

Yes but I only ever add to the stops from 12m and up as additional safety for actual dive conditions I never shave the tables I am not in that much of a hurry to get out.

Originally Posted by [b

Quote[/b] ]It's up to you. 30/90 is good and so is 20/85.

Good it's the one I use most

Originally Posted by [b

Quote[/b] ]I was talking about another incident - This one. Hence the confusion. I do recall the one you are talking about though.

Yes I mentioned that one too. They did about 18mins of stops from 12m including the 6m stop and Decoplanner said they should have done 31mins., errrr slight diferance and what do you know they got bent but hey they only shaved about 45% off of their shallow stops I cant understand how it could have hapened

Originally Posted by [b

Quote[/b] ]The point you are missing is that thanks to my training with GUE I don't think your tables and computer combination is the best of both worlds. You just think it is because you have not been shown a better way of doing it. No problem, just don't rule out the possibility that you may be wrong.

I am wrong loads of times just ask the wife &nbsp;Hey I am not saying I know best and I have given Andy a chance to show me how the profiles can be modified outside the accepted norms and stay safe. If DIR or any one else do a seminar on maping deco profiles I will be first in line to sign up. If you would like to breifley outline how you go about altering a profile I (and I am sure others) would be very interested to lurn and very open minded. To just say tables are best is a mantra not an argument.

The main purpose of a forum is debate. I am here to debate I will put forward my argument and listen respectfulley to yours. I am obviously firmly in the computer camp but my attitude to diveing is, if somthing better /safer comes along do that.

ATB

Mark Chase

[Mark Chase]

Originally Posted by [b

Quote[/b] (wetlettuce @ Sep. 06 2003,17:37)]

130GF High?? do you understand what that meens. 100% is the MAXIMUM theoretical off gassing limit. Above 100% is the area where bubbles form at a size that would result in a bend.

Using 100% + Lo is done by some divers but that meens they are actualy getting bent in the slower off gassing compartments half way throuh deco and fixing it on the shalow stops Bend and mend. 100%+ high is total rubbish. A profile at 130% high is a bend profile reserved for experimental edge of the envalope stuff and very very personal to the diver concerned. To plan a dive like this would take years of personal tolerance experiance. That said I still think getting out 20 mins early is not worth the risk of a bend.

Originally Posted by [b

Quote[/b] ]Perhaps you should read the title of the thread again. DIR and computers. It seems each topic recently you bring this up. I shall if you wish find reports of people who suffer DCI whilst obeying their computer. Will that progress this discussion constructively ?

If you read my thread you will see that I too have picked up people diving blindley on computers and got bent and pointed out the masive errors in their profiles. I did this very thing to a chap on YD who got bent and blamed his computer this year. The point I make over and over again but you have ignored is that the computer should have a baseline for comparison. Unless you are diveing two VR3's that comparison has to be tables on a mix dive or a deco dive. So you have to cut the tables and understand the data. If you cant you shouldent be doing that level of deco diving.

I pointed out VERY clearley that the computer will not take into account conditions of the dive and the divers state of health and the diver should have the knoladge to pad out the deco profile to compensate for this. Again you have ignored my comments.

Originally Posted by [b

Quote[/b] ]You are saying the accident/incident happened because they didn't have a computer,

I am saying the computer would have told them they needed far greater stop times than they had planned. If they chose to ignore the computer and follow the tables they would have still got bent. But it would have alerted them to the probem.

So You and I have just done a 65m dive we are both on tables and VR3's We hit the 9m stop and we see on our tables that we have 5 at 9 and 15 at 6 but your VR3 set to 0 safety states you have 45mins to the surface. You compair with your buddys VR3 and it says you have 43 mins to the surface.

So do you think:

A: Both computers have gone wrong and are talking rubbish even thow the rubbish is within two mins of each other

B: The computers are showing 45mins but thats for wimps our tables show 20 so lets folow them

C: Bugger we might have screwed up our tables we had better do 45mins of deco and check them when we get home

Come on Andy honistly what would you do?

Originally Posted by [b

Quote[/b] ]The only way the model was created was by chucking people in the water and seeing if they suffered DCI. If they did then the limit was lowered. The US Navy tables even built in a DCI probability meaning that it was acceptable for 20% of their divers to suffer DCI. Hardly accurate or even relevant to our own particular physiology.

Actualy it was a snake a goat and a donky. The Germans did a bit of unethical decompresion work in the Jews in the second world war too and NASA used that data quite extensivly I beleive and some of it filtered down into decompresion theory. Every one knows the Navey tables are risky. They dive PP02 of 2 as well.

I own and dive a VR3 and I cut tables with low GF's for deep stops. I can tell you that the VR3 gives a very similar run time to tables when the profile matches the tables. To date the computer hasent been more or less than two minuits from the table times when compired after the dive on computer simulations.

I can also tell you that just like on my last dive where things went a bit wrong I am always clearing the computer and adding deco at the 6 and 3m stops dependant on how I feel on the day. I added 10 mins to my last bad dive 6m stop and spent a further 5mins geting to the surface after that.

Originally Posted by [b

Quote[/b] ]Decompression as you know is not an exact science and some will get DCI even on the most conservative of profiles, there is a thread about that 'Call me Bender' or something in the medical forum. I know someone myself who obeyed the computer but suffered DCI but he was overweight and a smoker. How does the mathematical model compensate for that. It doesn't so the diver has to.

I am over weight and a smoker so I run 20-80 profiles and pad the shalow stops if I dont feel to good on the day. You could set the computer for a higher safety level to compensate and still folow the computer but I like to make my own choice as to the extended deco rather than bend the computer if I need to push the limits on a given dive.

God how many times do I have to say this: You dont OBAY the computer you use the information it gives you as a guide.

Originally Posted by [b

Quote[/b] ]Learning how to adjust the deco curve to suit your own limits is part of DIR.

Yes, So dive a few conservitave profiles say 35-85 and see how you feel. Then do say a 20-80 and see if you feel better or the same. Its easy with planning softwhere to find your comfort zone.

Having found your comfort zone then see how it matches the computer profile. If its close fine if not then try safety setting alterations or GF alterations on the dive computer to see if you can get it running nearer to your prefered profile.

With my old Vytec I used to add all the deep stops off of a table untill I hit the 9m stop then follow my computer on the 9 and 6m stops. It worked well for me.

Originally Posted by [b

Quote[/b] ]I am happy to justify why DIR believe that computers are not needed but I shall not justify someone elses dive plan as I was not party to the discussion or to the advice they were given. Lets keep it on topic Mark and move on.

I dont think you can justifie their dive plan and I wouldent ask you to normaly. However YOU put in the comment that the tables were fine and it was their multiple dive and post dive antics that caused the bend. So I asked for justification of you comments. &nbsp; &nbsp;

As it turns out Mr T reckons they blindley copied their profiles off of another diver reputed to be unbendable Bob. If thats true then they are dangerous and I wouldent dive with them.

I think I have stayed on topic by demonstrating that divers without knoladge of deco are in fact more likley to get bent on tables than on computers. I have also demonstrated that a computer needs to be used by a knoladgable diver to make it a safe tool. I diver who is fit and strong and holds good profiles could possably go through his or her diving carear only ever folowing a computer and not get bent, but the rest of us need to take greater care.

ATB

Mark Chase

[And]

<font color='#0000FF'>Hi

Mark, I don't ignore any comments just pick those were I feel I can comment. Most other comments I either agree with or will expand on them later. Otherwise we'd end up posting three page responses which are too hard to read.

The theory/policy/training of GUE and computers is not only based on technical diving. Technical divers will undoubtedly know more about tables and diveplanning etc. It is also the recreational divers who do fly by computer. I know you take the time to understand and have contingencies but others don't and that includes Technical divers too.  

The VR3 may be an excellent computer giving you a total time to surface but others don't. You dive with plenty of exrtra gas just in case. Other divers are just on a single cylinder. I'm sure you can appreciate that all this isn't aimed at you.

It is possible to create profiles on a computer to mimic anything you want. That is my point. I wouldn't use such a high GF but I would be willing to adjust the profile to try to make the deco more efficient and less of a 'bend and mend' profile. For example the link Mark posted shows that the best depth to start deep stops is 80% of the ATA's or 75% max depth (I think if you take the 75% and then add 7mtrs you get the same number) With GF's and the Buhlmann model you will start stops later. That is not where you start offgassing, it is where you hit the chosen gradient and not of the fastest compartment but all compartments. Your fastest compartment will have had to cope with a pressure change up to five times greater than the rest of the decompression allows.

If you decide to ignore the table producing PC and its safety limits then you will likely ignore the VR3, which will have some kind of cancel button anyway for it to show best guess that you mentioned. You can't police for that and even analysing the event afterwards is pointless other than a 'well we'll never do that anyway' type response.

You asked what I would do in your scenario. I would have used a standard gas, for which there will be a standard deco which I will have in my wetnotes. The profile would have been planned and discussed before the dive. I would compare my wetnotes to what I'd done so far. Any missed stops would be added to the shallow stops and then some. I wouldn't have a VR3 but if my buddy had one and was uncomforable with its warnings then I would stay as long as we had gas.

Hope that clarifies things a little.

Andy

PS and yes its SUnday, sunny out and my diving has been cancelled. Not the best day