PADI tables finally going away?

[lord.harshil]

People on this thread have said that computers usually don't crap out on you, and fair enough, they usually don't. Even if they do, slowly ascend to 15ft, do a safety stop and you'll be fine. I totally agree up until this point.

Now, consider this scenario :

30meter dive done by a diver who isn't an air hog and its possible for him to exceed the 15min NDL with his AL80 tank.

Scenario 1 (using a dive com) : What if on a dive your dive computer doesn't fail on you but gives you the wrong depth? This is not uncommon judging from what I've read on the forum. Lets say you don't know the tables AT ALL and hence it is safe to assume that you do not know the NDLs at various common depths. The dive com shows you 20meters instead and you hang around past your NDL without realising it, come up, get the bends and DIE DIE DIE DIE.

Some critics might say that he didn't check against his depth against his console, but come on which recreational diver carries backup depth gauges and timers?

Scenario 2 (tables) : You know your tables, you know about the various NDLs (roughly) and you use less fail prone items like brass and glass SPGs and depth gauges and simple bottom timers. I've been using a $15 casio watch as my bottom timer (backup) for 3 years now with no hitch. Its nearly impossible for you to exceed your NDL as you know the NDL in your head and the casio watch won't give you the wrong time (digital watches don't slow down or speed up).

In both cases, if you equipment screws up you abort the dive with no problems. The problem comes when you don't KNOW that your equipment has failed, something that is obvious to spot in brass and glass and quartz, but not so obvious with a fancy dive computer.

Personally, I use a dive computer and love its versatility. I hate to use tables. They're very inefficient. But the simple act of knowing a few of the NDLs in my head and a $15 watch could save my life in the event my dive computer screws up.

 

[Tigerman]

lord.harshil your digital watch is nothing but a simple computer

 

[Puffer Fish]

I believe you misread his post. Here's how I read it.

He said "after a dive over over 6 hours at 100 ft... something I would find difficult to do on one tank, several tanks or anything I could possibly carry."

He is not talking about going into deco. With the PADI tables, the diver went into deco 5 hours and 40 minutes before that point.

He is referring to an earlier post in which it was asserted that computers abandon you if you violate deco limits. He is saying that his computer abandons him 5 hours and 40 minutes after violating deco limits, something that is never going to happen.

Thank you John (as always)...

I did not check the actual deco time, but it is around 7 hours (for the gas I happen to have in at the time)..I don't think I can get there on a single tank.

 

[Puffer Fish]

People on this thread have said that computers usually don't crap out on you, and fair enough, they usually don't. Even if they do, slowly ascend to 15ft, do a safety stop and you'll be fine. I totally agree up until this point.

Now, consider this scenario :

30meter dive done by a diver who isn't an air hog and its possible for him to exceed the 15min NDL with his AL80 tank.

Scenario 1 (using a dive com) : What if on a dive your dive computer doesn't fail on you but gives you the wrong depth? This is not uncommon judging from what I've read on the forum. Lets say you don't know the tables AT ALL and hence it is safe to assume that you do not know the NDLs at various common depths. The dive com shows you 20meters instead and you hang around past your NDL without realising it, come up, get the bends and DIE DIE DIE DIE.

Some critics might say that he didn't check against his depth against his console, but come on which recreational diver carries backup depth gauges and timers?

Scenario 2 (tables) : You know your tables, you know about the various NDLs (roughly) and you use less fail prone items like brass and glass SPGs and depth gauges and simple bottom timers. I've been using a $15 casio watch as my bottom timer (backup) for 3 years now with no hitch. Its nearly impossible for you to exceed your NDL as you know the NDL in your head and the casio watch won't give you the wrong time (digital watches don't slow down or speed up).

In both cases, if you equipment screws up you abort the dive with no problems. The problem comes when you don't KNOW that your equipment has failed, something that is obvious to spot in brass and glass and quartz, but not so obvious with a fancy dive computer.

Personally, I use a dive computer and love its versatility. I hate to use tables. They're very inefficient. But the simple act of knowing a few of the NDLs in my head and a $15 watch could save my life in the event my dive computer screws up.

Any depth gauge can fail..dive enough and that watch will , the gauge will... the spg will not read correctly....If doing a deeper dive, I always have redundency. Doing a dive to the sea floor, with a known depth... not so much.

Note: have even had a compass fail.. it broke on a entry drop.

 

[lord.harshil]

Any depth gauge can fail..dive enough and that watch will , the gauge will... the spg will not read correctly....If doing a deeper dive, I always have redundency. Doing a dive to the sea floor, with a known depth... not so much.

Note: have even had a compass fail.. it broke on a entry drop.

I know they'll fail eventually

Just saying the simpler something is, the less it tends to fail. Besides, the depth sensors on a dive computer are def more prone to failure than a simpler brass n glass depth gauge.

If you do happen to come across some gear thats indestructible do let me know

 

[The Chairman]

The dive com shows you 20meters instead and you hang around past your NDL without realising it, come up, get the bends and DIE DIE DIE DIE.

Dang, we made it past post 350 without someone having to DIE DIE DIE DIE! Oh well, it had to happen. Does it matter if it's your PDC or your depth gauge that's off? No, so your scenario that if you dive a PDC "You're gonna DIE DIE DIE DIE" is simply moot if not a tad silly.

The problem comes when you don't KNOW that your equipment has failed, something that is obvious to spot in brass and glass and quartz, but not so obvious with a fancy dive computer.

Why isn't it? If you pay attention at all it's easy to spot.

Personally, I use a dive computer and love its versatility. I hate to use tables. They're very inefficient. But the simple act of knowing a few of the NDLs in my head and a $15 watch could save my life in the event my dive computer screws up.

So you carry an additional depth gauge? If not, what's the difference? Anyone can dive the rule of 120. But I wonder how often you check your watch as you splash?

 

[ScubaSteve]

Why isn't it? If you pay attention at all it's easy to spot.

I personally think this is entirely dependant on the specific failure. If it starts to count slower or quicker (anything is possible) then this would be a challenge to notice. If your depth all of the sudden dropped or jumped....then yes. If you went into deco immediately following splashing...then yes. But there are problems that would likely not be easily noticeable.

 

[The Chairman]

I personally think this is entirely dependant on the specific failure. If it starts to count slower or quicker (anything is possible) then this would be a challenge to notice. If your depth all of the sudden dropped or jumped....then yes. If you went into deco immediately following splashing...then yes. But there are problems that would likely not be easily noticeable.

I would imagine that %99 of all problems with PDCs are them not working at all. With all of my dives on PDCs, I have only had one fail. Of all of the peeps diving around me, I have witnessed one other failure. I have seen more SPGs fail, but only one depth gauge fail and not read right. Of course, the numbers are not equal, and I have yet to see near as many depth gauges as I have PDCs. Most PDCs calibrate at the surface which is something that depth gauges can not do.

But really, if the dive master told me we were on a 60 fsw max reef, then I would expect to see just that. If there is a discrepancy, as there often is, I check against another PDC or depth gauge. I find that dive masters often "lie" as I tell my students. No, they aren't trying to, but my PDC is far more reliable than their dive briefings.

 

[DiveNav]

........What if on a dive your dive computer doesn't fail on you but gives you the wrong depth? ......

........ and you use less fail prone items like brass and glass SPGs and depth gauges and simple bottom timers. ......

Why is a mechanical depth gauge less prone to failure than a dive computer?
As far as I know, the MTBF of electronic components is much higher than that of mechanical components.

 

[boulderjohn]

Note: have even had a compass fail.. it broke on a entry drop.

Interesting. In the past 6 months I have experienced several compass failures, all Suunto SK7s, one of the best compasses you can get. It appears to be a foolproof design, but I have witnessed at least 6 failures in this calendar year. To be fair, only 3 were the compass itself. The others were failures associated with the DSS wrist mount in which it was sitting. (On hot days the mount gets too soft, and the ridge on the bezel base slips out of the notch that holds it in place. It can fall out completely.) I don't believe I have witnessed that many computer failures in my life.