In dive, manage having EAN programed into computer while diving air?

[PfcAJ]

Tables have nothing to do with this at all, it is about paying attention to your equipment and establishing a routine/habit/check list that includes verifying your computer's settings.

Nah that’s backward.

A plan is “I’m going to this depth for this time”. Relying on a computer isn’t a “plan”. It’s reactionary.

No part of your dive should be a surprise.

 

[BoltSnap]

Nah that’s backward.

A plan is “I’m going to this depth for this time”. Relying on a computer isn’t a “plan”. It’s reactionary.

No part of your dive should be a surprise.

For a recreational diver who is using a dive computer, tables are irrelevant especially if you are making a multi-level dive (vs. square profile). Try it, go to 30 meters with a dive computer and work your way up and do it another time using dive tables and your computer in gauge mode and see the difference in NDL's.

 

[flymolo]

Op, if memorizing a table of NDLs seems difficult what about writing them down in your wetnotes? Can even put a few common deco schedules in there as well..

 

[saridnour]

Its not a matter of memorizing tables. As a shore diver I am not diving square profiles so its all a guessing game with my best estimate winning when thinking back to a table. Still think it would be a great feature to be able to recalculate your dive profile using an updated gas in dive. All the telemetry data is there so its just a matter of recalculating. Yes the option would need be fool proof to implement but I can see it being useful in situations like I had. We (most of us) dive a computer for a reason, we have the data so its already there. And you also need realise tables are not taught as they once were to new divers so there really could be an issue where one could need this "emergency" feature. Just my 2 cents.

 

[flymolo]

Its not a matter of memorizing tables. As a shore diver I am not diving square profiles so its all a guessing game with my best estimate winning when thinking back to a table. Still think it would be a great feature to be able to recalculate your dive profile using an updated gas in dive. All the telemetry data is there so its just a matter of recalculating. Yes the option would need be fool proof to implement but I can see it being useful in situations like I had. We (most of us) dive a computer for a reason, we have the data so its already there. And you also need realise tables are not taught as they once were to new divers so there really could be an issue where one could need this "emergency" feature. Just my 2 cents.

Even if you are not diving square profiles couldn't you calculate ascent profile based off average depth of the dive?

 

[dmaziuk]

Even if you are not diving square profiles couldn't you calculate ascent profile based off average depth of the dive?

Yes. Could you calculate ascent profile that gets you out of the water not bent? Also yes. Hypothetically.

 

[flymolo]

yeah, i wasn't going to go as far to suggest ratio deco since OP says he is diving air, but you could definitely use ndl tables or some pre-planned deco schedules based off the average dive depth. i'm not sure how multilevel vs. square profile matters in this case since you'd be averaging depth..

 

[wnissen]

Even if you are not diving square profiles couldn't you calculate ascent profile based off average depth of the dive?

I thought you could not. Isn't the nitrogen loading in the fast tissues a diffusive process where the concentration is proportional to the pressure? So the rate is proportional to average depth but the nitrogen load is the integral of the rate and therefore not linear. All the models are systems of differential equations, there is no linearity in them that I am aware of.

 

[Wibble]

I wonder how hard it would be to have an air integrated computer detect the gas being used?

Doing so might require some additional maintenance of the transmitter, but keeping it only accurate enough for an idiot check may be of some value, increase safety and be of minimal hassle.

I don’t know enough about them to know if there is room to add this functionality.

A flashing screen that tells you this gas doesn’t seem to match your settings would be a good reminder in this case.

Would that mean scanning/reading the gas analysis tape attached to your cylinder?

The point of diving mixed gases is you must do the correct analysis and that goes onto the cylinder. As part of the pre-dive checking (like does it work) you read the analysis tape and check your computer.

Alas, it's not being pedantic, the penalty for getting that wrong could be death!

 

[saridnour]

It's all a matter of how close you get to the "M" value and how well your body handles DCS. Technically we all get DCS, its a matter of what we observe. I dive a very conservative gradient factor (35/70) and use that as my guide to keep me away from M. I watch my surf GF delta5 and other factors on my computer as a decision factor in where to be (depth) and when to end my dives in many situations because I have that liberty. Most of my dives are just "fun" dives. We may have a very high level plan but not done to a tech level of planning as things so easily change on our local weekly shore dives. We may play with a harbor seal @30ft, observe a 6 Gill shark at @120ft or spend extra time trying to get that perfect photograph of a GPO or wolf eel. We spend more time in events like this than you can really plan for. It's easy to say plan, but we all know the truth in dives like that. Yes you can average but that does not take into effect tissue loading the way a computer can. A computer gives a diver a better estimate of how close to M they are using all tissue compartments in the Bühlmann model. A table can't do that as pointed out above. A table can give you an idea but those table do push us toward M more than I like. I would love to have to do less guessing and have more real data to work from and where adjusting an air mix on the fly and having it recalculate the model would be great in "emergencies" like that. Computers already have the capability to recalculate TTS based on available gas or gas that is switched while in dive. This calculates TTS based on your GF/conservatism settings and what it takes to get to the surface. Those are fixed numbers. There is no reason a computer can not easily do that inverse over your profile. Even if its just a adjusted tts or ceiling icon/number vs an overall change of the data. I dove for years on tables without a computer. There's a reason we all use computers know and that flexibility is amazing. I just see this as a bit of a hole in computer design for the modern rec diver.

And that being said, knowing the rules of thumb listed above are great to know and will be used by me in situations like that. Any estimate is better than a none!