[dapl]

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Peter K,
Thanks for the post on your bend. Hopefully you are on the mend now. I am a bit curious about your perception that it was your computer at fault. Did your dive buddies computer miss the same amount of stops as you reckon yours did?

 

[peter k]

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I did NOT miss any computer stops. That's the point. My buddy did less than me to be truthfull, but there was points in the dive where I went wee soiree's(+10mtrs) deeper than him. I have realised that saying it's the 'pooters fault does bring up bones of contention in the fact we all use them and(I did)trust them. I did what I was told!!!! It leaves the questions; Are the computers basicly dangerous or is my body more suited to table diving? I think it is a mixture of the two options. The difference in deco I missed compared to the Buhllmans and my 'pooter was 8mins on dive 1 and dive 2 was off the table. As I said in another thread the lowest my 'pooter got to was a 5min no stop in dive 2. The reason I tend to go with Buhllmans is that Navy tables were designed around fit, healthy Navy divers. Buhllmans, I believe, were not. As an example, the next time you go for a dive, follow your computer then check tables after you get out. I think you might see a big difference in stops.

Peter  

 

[Gavin Yates]

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Pete,

Which pooter were you using and had you got it set for the most conservative setting ... considering it was Winter and cold and shit.

Just a thought .... I have me Vytec set on the most conservative at this time of year ... just to be on the safe side.

 

[darthmoll]

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Quote[/b] ]Quote: from peter k on 11:37 pm on Feb. 5, 2003
As an example, the next time you go for a dive, follow your computer then check tables after you get out. I think you might see a big difference in stops.

Peter  

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Without stirring things up, i hope, that is what computers are ment to do, give you an accurate dive schedual based on what you have actually done, tha basic rules must still be followed. Looking at the time you said you spent at depth on the first dive and your ascent time i am still thinking you chased the computer to the surface, only you can tell us that, in its self not best practice, but not the end of the world, if you follow the rules, i mean the computer is a tool not a magic box, i have done hundreds, around 1500 dives on computers and have never had a bend, but i do not expect it to think for me, i always follow all deco rules, it is just a pity to blame such a good tool coz people dont follow the rules.

BTW watch out for my bend report next week.

 

[dapl]

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Quote: from peter k on 11:37 pm on Feb. 5, 2003
I have realised that saying it's the 'pooters fault does bring up bones of contention in the fact we all use them and(I did)trust them. I did what I was told!!!! It leaves the questions; Are the computers basicly dangerous or is my body more suited to table diving?

Peter, maybe table diving is safer for some people, you included, but have you sought any other professional opinions on which (tables or computer) is best and safest for you? I would guess that you may need to find this out before you decide your diving future.

(Edited by dapl at 8:31 pm on Feb. 6, 2003)

 

[Rob Evans]

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I'm not sure about this talk about pooters.  When reading Peter's report, the very first thing that struck me was the long kitted up surface walks to and from the dive sites.
To my mind, those were the source of the bend from the very word go.
You can dive within tables or computers as much as you like, but if you start the first dive with a real possibility of excess CO2 still hanging around your bloodstream, finish the dive with another long slog and repeat the process for the second dive you're looking for trouble.  It's well known that excessive physical exertion post-dive can have a great effect on the body's ability to off-gas - unfortunately no dive computer anywhere can compensate for this.
I'm quite happy to do long deep dives with - so far - up to 1 hr breathing high PO2 nitrox mixes for decompression and let the pooter handle the whole dive (backup tables in pocket).  What I'm also very careful to do post dive is sit on my fat arse and do nothing until it's time to get into the water again or go home.
Personally - and with absolutely no slight against Peter cos I'll be seeing him on the Mull gig soon and I enjoy having my bollocks exactly where they are thank you very much -  I'm not at all convinced it's the pooter's fault.  Excess exertion, maybe not as fit as he'd like to be and not forgetting the slight possibility of a PFO all look more likely suspects.

 

[Andy G]

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I remember a wise Oldish :sofa: man once saying that the problem with computers is that they are Silicon and we are Carbon.
Now I am a 6'2'' 17 something stone:burgereater:, beer drinking:klo:, smoker and whatever my computer tells me I always do at least 5mins more if normal diving and double that if deco. diving. My view is simple whats 5-10 more minutes in the water compared to 4+ hours in a pot...and the slagging that I would definetly get should the pot happen to be local:thumb:.
Yes I like computers as a guide but would I bet my health on one .....NO.  

 

[peter k]

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Just to try and answer some of the above questions;

Gav, I was using a borrowed Aladin Sport. Yes, I know, not the best deco computer about but my own computer is broke, hence the borrowed one.
DarthVader, As far as I know computers algorithms were figured out in chambers with most of the basics working off Buhllmanns. This would not take int account temp, workload, etc. These things were added on at a guess factor into the algorithms. All instruction books for them tell you not to use them solely for deco info and the Suunto Stinger tells you on page 1 that if you use it for deco you WILL suffer a DCI. I'm not saying that they're a bad thing, just that they should be complimented by the best dive computer you've got, your brain. Instead everyone seems to have follow them like lemmings. What I say is take Buhllmans down with you and if their is a big difference in them to what your computer is telling you, follow the Buhllmans. After all, we're all told to follow the most conservative, aren't we?

Rob, I know about the walks, but, these two dives are dives I have done many times before and in the same way. I think it was just my day for the lightening bolt.

Andy G, Wise man!!!!  

 

[Mark Chase]

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There is no doubt in my mind that the computer had a fault or that it was mis read during the dive as it was a strange bit of kit.

I ran the profile on my Vytec

37m for 42mins allowing for ascent and 8min stop is aproxamatly a 30min bottom time;

On air thats 37mins deco
No Nitrox 30 running a PP02 of 1.4 thats 22mins deco

Surface intervall of 2 hours

31m for 40 asuming deco and ascent time again bottom time
30mins

31m 30mins on air 53mins deco
31m 30mins on 30% Nitrox 19mins deco

Running the profile on Deco planner using 35 80 gradiant factors gave 24min and 19min on Nitrox 30 and runing it on air came up with 49min and 42min deco

All in all the profile dosent make sence. I can only asume that it was a multy level dive with the vast majority of the dive at a much shalower depth. I ran a few profiles and to get 8 mins deco on air for the first dive  you coud do 5 at 37, 5 at 30, 10 at 25, 10 at 20, On a 30 85 that came up as 9mins of stops.

Please note that was Normal settings and safety off

I would be a bit more conservitave given the conditions surounding this dive.

This is NOT a slag off. This is just pointing out that the figurs dont add up so there must be more to the profile than I have read or the computer is buggered.

Now I dont normaly cut tables for a no deco dive BUT I do check out the dive plan on the PC before the trip so I dont sudenly find that my planned bottom time is going to be well into deco. I also carey INTD bail out tables so even if my computer gos tits up I have some form of get home plan. I offten dive the computer even on serious multi gas dives but I always have a mentle picture of the profile in my mind before the dive so when my computer shows me garbage I will / should notice it.

If I am over seas I dive two computers if I cant get to a PC to plan the dive and do a rough profile on the IANTD tables.

Computers are good but they have to be monitered cairfulley coz all things electrical are the acursed spawn of the devil.

Mark Chase  

   

 

[Phil Ennis]

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Peter K,
How are you doing?
Just a point with your comments above. After reading I dug out my Stinger handbook but mine states nothing of the sort. It advises against commercial or professional use. In the dive mags it is advertised as having 'Full Decompression Capability'. You either have a different manual, or you have been taking lessons from Bren in 'Poetic embellishment'.
Only joking Bren !!!! and Peter..

 

[Andy Phillips]

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I think the main point here is being missed. We ALL rely heavily on dive computers, more out of lazyness than any other factor, how many of us drop to 30M and do anything other than follow the profile the computer tells us to. I whole heartidly agree with and follow Mark Chase's approach to dives byond 30M and have cut a profile on a PC and an idea what the tables would say. As far as computers are concerned, all of us have been told repeatidly during our training that computers are NOT infalible, we are fools to belive otherwise. Peters bend was bad, and should be taken as a lesson to us all to think before we enter the water. I belive this was Peter's intention when he posted the information is the first place.

Andrew

 

[darthmoll]

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Quote[/b] ]Quote: from peter k on 2:09 pm on Feb. 7, 2003
Just to try and answer some of the above questions;

Gav, I was using a borrowed Aladin Sport. Yes, I know, not the best deco computer --it is actualy sold as a non deco computer

This would not take int account temp, workload, etc. These things were added on at a guess factor into the algorithms.

Tables take into consideration workload, temp etc? none that i know about, you have to add them.

All instruction books for them tell you not to use them solely for deco info---i think you will find that tables tell you that they do not gaurentee that you will not get bent

I'm not saying that they're a bad thing, just that they should be complimented by the best dive computer you've got, your brain. ----that is my point exactly, if you or should i say one coz i am not havin a go at you, forget the 'rules' chances are you will get bent.

Instead everyone seems to have follow them like lemmings.--if the cap fits

What I say is take Buhllmans down with you and if their is a big difference in them to what your computer is telling you, follow the Buhllmans.

why bother using a computer, i worked as a guide in the red sea, and i know that if i followed my BSAC tables i would not have been able to work, we are back to the square profile thing.

After all, we're all told to follow the most conservative, aren't we?

Thats true, but if you had not done the yomp and the short surface interval you may not have got bent..

oh and its darthmoll, vader is well hard

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[Ian W]

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Quote[/b] ]Quote: from peter k on 11:37 pm on Feb. 5, 2003
The difference in deco I missed compared to the Buhllmans and my 'pooter was 8mins on dive 1 and dive 2 was off the table. As I said in another thread the lowest my 'pooter got to was a 5min no stop in dive 2.

As an example, the next time you go for a dive, follow your computer then check tables after you get out. I think you might see a big difference in stops.

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Better yet, check the tables and the computer's dive planner before you go in! But anyway, unless you do square profiles and exact surface intervals as listed in the tables, comparing the stops given by a dive computer with those from a decompression table is pointless.
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Quote[/b] ]Quote: from peter k on 11:37 pm on Feb. 5, 2003
The reason I tend to go with Buhllmans is that Navy tables were designed around fit, healthy Navy divers. Buhllmans, I believe, were not.

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Another justification would be that Aladins use Buhlmann algorithms, though not necessarily the same model as the tables.

Ian W

 

[darthmoll]

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Quote[/b] ]Quote: from Ian W on 1:15 pm on Feb. 8, 2003

Quote: from peter k on 11:37 pm on Feb. 5, 2003
The difference in deco I missed compared to the Buhllmans and my 'pooter was 8mins on dive 1 and dive 2 was off the table. As I said in another thread the lowest my 'pooter got to was a 5min no stop in dive 2.

As an example, the next time you go for a dive, follow your computer then check tables after you get out. I think you might see a big difference in stops.

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Better yet, check the tables and the computer's dive planner before you go in! But anyway, unless you do square profiles and exact surface intervals as listed in the tables, comparing the stops given by a dive computer with those from a decompression table is pointless.

here hear

 

[MATTBIN]

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Have I got this correct? It is suggested that unless you compare the predicted profile from the computer to the table and use the most conservative (invariably table) that you run an increased risk of getting bent? Virtually everybody runs a computer and uses that to calculate their dive plan, particularly on multi-dives, which gives greater bottom time than a table. So by doing this we all run the risk of getting bent to a far higher degree than if we used a table based plan? If you are going to compare table to computer dive plan the table will always be more conservative, so why bother with the computer, why not use a depth timer and table? Becaus we all like the extra a computer gives us. So we take the risk and sometimes we get a hit, the more adventurous the plan the more the risk. The higher the risk the more we should be aware of any symptoms.
Matt

 

[Dr Stevil]

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Basically, yes, tables assume a square profile, computers don't, so tables will always be more conservative.

Personally, I don't care what the computer says, if I'm going beyond 25 metres I will do at least a minimum of 3mins at 6m, over 30 I'd increase it to about 5mins minimum, and the day I did my deepest ever (around 40m, coincidentally enough in the same area as Peter was that fateful day) I spent no less than 10 mins bimbling around at around 6metres, I was bursting for a leak all that while but off gassing was my primary concern . These days I'd be inclined to use EAN50% if I was going beyond 35m, and I'd be on it as soon as allowed(ie 18 metres). Cautious old fart I may be (41) but I'd quite like to be still diving when I'm 51 or 61 or older, plus I had a friend who very nearly died due to a DCI incident, most likely because of an undiagnosed PFO.
Chee-az
Steve

 

[MATTBIN]

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Quite agree Steve, but it seems that it is being suggested that Peter brought it upon himself by diving to computer only and not consulting tables, glass houses spring to mind. Look we are all at risk cos we use computers and/or tables, just be aware of the symptoms and get potted if they strike. Dont DENY is the real answer here.
I like your plan, being around till you're 51 or 61 or whatever, total dive time will be greater than these whipper snappers anyway old boy.

 

[darthmoll]

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Quote[/b] ]Quote: from MATTBIN on 5:27 pm on Feb. 10, 2003
Quite agree Steve, but it seems that it is being suggested that Peter brought it upon himself by diving to computer only and not consulting tables, glass houses spring to mind.

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IMO much more serious than only using a computer and not consulting tables is not following deco rules, coz no table or computer can deal with you not following the rules, no yomping, drinking alcohol and so on. It is too easy to forget the rules, remember old divers, bold diver but no old bold divers.

 

[Dr Stevil]

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Quote[/b] ] remember old divers, bold diver but no old bold divers.

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Arrrrr... words wise from he that is evil Sith lord

 

[John Gulliver]

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That old platitude again!
Concise Oxford Dictionary, Ninth Edition:
Bold adj. confidently assertive, adventurous, courageous
Why shouldn't there be old, bold divers? Bold does not mean reckless.