Another Tables vs. Computers Thread

[lamont]

Pride and arrogance (aka ego) have killed more people in this sport than just about anything. IT IS YOUR ENEMY. Only a fool would contend otherwise. But sometimes people just can't handle the truth.

GI3 has been known to pull tables out of his butt. So what? You won't catch me following tables built on a gut feeling. That turns a SWAG (Scientific Wild Arse Guess) into a DWAG (Delusional Wild Arsed Guess)! The former is bad enough!

I turned off my computer, not because of ego, but because I was consistantly able to execute the dives that I do with the same accuracy as the computer and I got tired of going diving only to find I had forgotten to set it to 32% and it gave me some obscene deco obligation. If they had a feature to adjust your mix because of an incorrect setting it'd be a little more useful, but that lawyers wouldn't like that, because they figure people would abuse that and get bent.

I also have not yet met a deco algorithm that I like. The RGBM-ized Buhlmann in the Suuntos doesn't give deep stops, and the VPM implementation in v-planner seems to give fairly correct deco times, but doesn't give sufficiently deep stops. That may sound like ego to you, but I feel I've done enough research on the physics of decompression to make informed choices.

 

[blueeyes_austin]

OTOH, since it is all a pretty rough approximation anyway, it is feasible to keep reasonable track of average depth and deco status in your head.

My issue with relying solely upon mental tracking is not whether it can be precise enough, or whether it is as accurate as a computer. My issue is that I am sometimes forgetful, sometimes distracted, and sometimes screw up badly in mental calculation. I prefer to keep rough track in my head, and compare that to what my computer says.

And that is exactly where I am coming from. The computer is a very precise nitrogen-load estimation device that doesn't get distracted by an eagle ray, lose track of time while trying to puzzle out what a dive partner is trying to communicate, or mentally fudge a "quick look" at an artifact below one's dive plan.

That said, if the computer is blissfully reporting that I have 150 minutes of NDT after I am at 20m and a half hour into a dive that went to 35m...well, that's when my rough tables in my mind (and generated by experience through observing NDT changes while diving) will kick into gear.

 

[H2Andy]

do you need a computer to dive? no

can you dive without a computer? yes

if you dive without a computer, do you have to undesrtand
decompression theory really well? yes

can you still do those same dives without understanding
decompresion theory really well by using a computer? yes

does diving with a computer make you unsafe? no

does diving with a computer turn your brain off? no

 

[JeffG]

I turned off my computer, not because of ego, but because I was consistantly able to execute the dives that I do with the same accuracy as the computer and I got tired of going diving only to find I had forgotten to set it to 32% and it gave me some obscene deco obligation. If they had a feature to adjust your mix because of an incorrect setting it'd be a little more useful, but that lawyers wouldn't like that, because they figure people would abuse that and get bent.

I also have not yet met a deco algorithm that I like. The RGBM-ized Buhlmann in the Suuntos doesn't give deep stops, and the VPM implementation in v-planner seems to give fairly correct deco times, but doesn't give sufficiently deep stops. That may sound like ego to you, but I feel I've done enough research on the physics of decompression to make informed choices.

Also, you can now adopt new ideas without having to buy a new computer.

 

[limeyx]

No, whether it's a "depth cieling" or a real one, this a deco dive is NOT an OW dive.
They really have no idea. PUSHING them in this direction before they even get wet is unconscionable.
The difference is between a "precautionary" or safety stop and an obligated one. OW students have NO BUSINESS over complicating the way they dive with additional theories that have no bearing on what they are trying to accomplish. I guess I could demand that my OW students handle a reel and carry three lights as well.

I think at this point it's pretty clear that no agreement can come of this.
If you actually had done some research or were really willing to listen I dont think you would see it as overcomplicating OW diving -- more that the "standard" safety stop might be "undercomplicating" it too much.

Also I did not mean to imply that the techniques that I use impose a mandatory stop on a recreational dive. They do not. It's just that it's way better if you are able to meet those stops.

 

[Scuba_Steve]

sorry gents,........Soggy your PM box is full

 

[Charlie99]

I turned off my computer, not because of ego, but because I was consistantly able to execute the dives that I do with the same accuracy as the computer and I got tired of going diving only to find I had forgotten to set it to 32% and it gave me some obscene deco obligation.

This seems to be the most common problem --- you, Mike Ferrrara, and limyx all have reported this as being the big problem with computers.

When you were diving with a computer, when it was set to the proper mix, did it ever restrict your profile?

The only legititmate complaint I've seen about dive computers forcing a diver into an unwanted profile was a Suunto computer that wanted to see 3 minutes total stop time between 20' and 10'. The particular diver preferred an approximation of a 10fpm linear ascent to the surface, with 1 minute at 30', 20', and 10' so the Suunto was a minute short on stop time. (One can argue whether or not the straight line ascent is anywhere near the ideal shape of deco, but in any case, that's what that diver wanted to do).

-----------------

do you need a computer to dive? no

can you dive without a computer? yes

if you dive without a computer, do you have to undesrtand
decompression theory really well? yes

can you still do those same dives without understanding
decompresion theory really well by using a computer? yes

does diving with a computer make you unsafe? no

does diving with a computer turn your brain off? no

Good summary of points. I propose another one -----

Does diving with a computer force you to do a profile other than what you would do without it? No.

 

[jiml]

Andy,
Why do you say that you have to know decompression theory really well if you dive without a computer? I don't think using the RDP really requires any understanding of decompression theory.
However, I do think that it's nice to know at least a little bit about it whether you use tables or a computer.

 

[Scubakevdm]

Use both.

 

[lamont]

This seems to be the most common problem --- you, Mike Ferrrara, and limyx all have reported this as being the big problem with computers.

That's the major problem with them in recreational diving. As a major problem its not a huge one, but I prefer to address the problem by turning my computer off. YMMV. In technical diving this is indicative of a larger issue in that you have to be telling the computer what gas you're breathing (even if you're on a rebreather, you can still come off the loop during a dive) and when the gas switch is stressful (lost deco gas, OOA due to bad mouthpiece, etc) you may not keep the computer in synch. Then there's the problem that I don't like the deco profiles that any computer program I've come across generates so far. Plus if you rely on a trimix computer for deco, then you really need two of them (and I recall one episode of DSD where Chatterton got out complaining that both his computers fritzed out on him...).