Why the Prejudice about DIR or GUE

[OHGoDive]

If you make an error such as forgetting to set the computer to the correct mixture of Nitrox, the computer should allow an in-water correction otherwise a computer is reflecting an incorrect state of gas loading. The programmers could write routines which allow for this correction, but obviously they don't trust people not to give themselves more BT than deserved. There is no other reason that can account for not allowing this correction. Why doesn't a computer allow you to switch it to gauge mode after diving a dive in computer mode? Again, it doesn't trust you to make a good decision.

You pretty much put the computer in control of your diving. I can imput reality into a software program like GAP, Vplanner or DecoPlanner and get the real picture, but not an in-water computer like a Suunto. I use my gas switching Tusa computer more often as a computer than the Suunto Cobra because I can program 2 gasses and switch in the water.

I'm not so sure that putting the computer in control of your diving is the logical conclusion from making an error from which the computer may or may not be able to continue to calculate properly. If you realize the moment that you've begun your descent that you've made a mistake, then ok, you could correct the setting, say from air to a 32% EAN and continue the dive no biggie. However, say you realized the mistake 5 minutes into your dive. How do you tell the computer what to correct? It's not just a matter of changing the setting from air to 32% and saying continue. It's a matter of what you've been breathing for the first 5 minutes and the computer recalculating the first 5 minutes of the dive to reflect what you're now saying is really in the tank. Does the computer trust the user to make that change, reliably, every time? While in the water? What if you programmed air, actually carried 32%, but inadvertently set it to 36%? (I know, you could make the same mistake at the surface, but are you more or less likely to make it at the surface or under water?) How many buttons would the user have to push to confirm that they really, really, want to change the mix setting mid-dive? It seems risky to me, and I can understand the unwillingness of the manufacturers. Add in even the slightest hint of narcosis and you've amplified all the issues.

If the computer defaults to air when you've forgotten to set it correctly before a dive (which, seems more likely to me than setting it to the wrong mix, but, ymmv), then you can trust it to give you maximum conservative settings on time, and can continue the dive. It's not controlling you to the point where you have to abort the dive, but, it is forcing you to be overly cautious, which, seems like a good compromise, under those circumstances. I mean, it was the diver who goofed, not the computer.

My Oceanic ProPlus 2 defaults to an impossible mix of 21% O2 and 50% N if you goof up and forget to reset the mix after diving anything but air, in order to limit both time and depth. It's overkill perhaps, assuming you've correctly calculated your MOD at the surface for what you're actually breathing. (Thankfully, it's a user configurable option to tell it to default to air instead of the impossible mix.) It's not resettable when it's wet.

I see it as "plan your dive, dive your plan." You might use vPlanner to plan your dive from your PC, write down the profile it generates, and that's the dive you make. You don't get to go back to the PC midwater and change the parameters if you want to descend an extra 20 feet, or stay 5 more minutes. The computer isn't controlling the dive. You planned it, you dive it. You goof it, plan better the next time.

 

[TheRedHead]

Does the computer trust the user to make that change, reliably, every time? While in the water? What if you programmed air, actually carried 32%, but inadvertently set it to 36%?

Since I'm may breathe several different gasses, depending on the dive, I guess I'm just screwed because the computer doesn't trust me to switch gasses. Could I inadvertently kill myself? Sure. But that's why you have a buddy to check your gas switch.

And if I had done a couple of recreational dives the first day of a dive trip and then plan to do a 150 foot dive and switch to 50% at 70 feet, I can't put the Suunto into gauge mode, but instead I have to bend it or do an excessive deco. That's when I use the Tusa which does switch gasses and it manages to recalculate the dive based on what you are breathing. But for Nitrox dives, I don't really need a computer because I have the NDLs in my brain.

I see it as "plan your dive, dive your plan." You might use vPlanner to plan your dive from your PC, write down the profile it generates, and that's the dive you make. You don't get to go back to the PC midwater and change the parameters if you want to descend an extra 20 feet, or stay 5 more minutes. The computer isn't controlling the dive. You planned it, you dive it. You goof it, plan better the next time

I want an accurate reflection of reality. I'm not changing my dive plan to suit a silly computer when I am perfectly capable of making the dive without the computer.

 

[ZzzKing]

Read the rest of the thread. There is much more to it than that.

Sorry, I gave up after about 30 pages. It seems no one really answered the OP's question but a goodly number may have illustrated his point.

 

[OHGoDive]

I want an accurate reflection of reality. I'm not changing my dive plan to suit a silly computer when I am perfectly capable of making the dive without the computer.

That's just it though. If you don't want to dive with the computer, don't dive with it. But if you do, it has to be set up properly. It has no perception of "reality" other than what it's been programmed (partly by you) with. Your argument is not far from one of not changing your dive plan to suit a silly single tank capacity when you're perfectly capable of making the dive with a set of doubles. Do it the way you want, but if you use it, you have to use it within the guidelines (and yes, constraints) of what it's been designed to do.

No sense griping over it. Get a different computer that does what you want, or choose an alternate solution.

 

[Dan Gibson]

And that is why you cut several tables. It saves frying the PC in midwater You need contingencies.

I see it as "plan your dive, dive your plan." You might use vPlanner to plan your dive from your PC, write down the profile it generates, and that's the dive you make. You don't get to go back to the PC midwater and change the parameters if you want to descend an extra 20 feet, or stay 5 more minutes. The computer isn't controlling the dive. You planned it, you dive it. You goof it, plan better the next time.

 

[Soggy]

It seems no one really answered the OP's question but a goodly number may have illustrated his point.

How do you know? You didn't read the whole thread

 

[TheRedHead]

No sense griping over it. Get a different computer that does what you want, or choose an alternate solution.

Griping about computers is part of the philosphy. Or have you forgetten the topic? With GUE's system you don't need computers and you don't need tables either.

 

[mrjimboalaska]

Computers? Tables? Are not those considered Office furniture?
If you have air.............."good to go"!

 

[TheRedHead]

No air either. Standard mixes.

 

[lamont]

That's just it though. If you don't want to dive with the computer, don't dive with it. But if you do, it has to be set up properly. It has no perception of "reality" other than what it's been programmed (partly by you) with. Your argument is not far from one of not changing your dive plan to suit a silly single tank capacity when you're perfectly capable of making the dive with a set of doubles. Do it the way you want, but if you use it, you have to use it within the guidelines (and yes, constraints) of what it's been designed to do.

No sense griping over it. Get a different computer that does what you want, or choose an alternate solution.

I quit diving my computer because I would often dive it as 21% when I was diving 32% (or 30/30... heh...), and underwater I would notice and want the option to retroactively 'fix' it to be 32% back to the beginning of the dive (or to be able to tweak the default setting to be 32% since I never, ever dive air). I wound up on one dive putting the computer something like 17 minutes into decompression, and when I was done with my decompression I was tired of being in the water, so I just bent it.

Now, you can argue that I'm not using the computer correctly...

But what I'm more worried about is down the road during a gas switch deep (190/120/70) when we have to keep on the move when the mouthpiece to my deco bottles comes off, so I have to go to 50% on / 50% off with one of my team mates and during this cluster I'm *not* going to want to be sitting there punching **** into my computer at the same time trying to keep it up-to-date on exactly what is transpiring during the CF...

And generally during a gas switch, I want to be focused on depth and on what gas everyone is breathing. I don't want to be punching buttons...

If you could stick a little O2 sensor in your throat that would (reliably) tell a computer what you're breathing under any circumstance that would be wonderful (an O2 sensor in a rebreather loop is close to this ideal, but it fails when you bailout to OC, and I'm not super happy with the reliability of O2 sensors and electronics and the state-of-the-art of U/W engineering for techreational diving...).