Article: Shearwater Announces Nitrox Recreational Mode for Petrel

[Progen]

Graham, I don't think many technical divers will trust their lives to wireless transmitters when going beyond recreational limits so it's not surprising that a dive computer like this doesn't have that feature. As for a digital compass, my Suunto has one but I find it a hassle to have to hold down a button to switch over and if you don't hold long enough to switch back, you get a new waypoint instead so I'll be getting a good old magnetic one to wear on my wrist as my MAIN compass. So much faster to just take a glance at your arm without having to press any buttons.

 

[Omisson]

Graham, I don't think many technical divers will trust their lives to wireless transmitters when going beyond recreational limits so it's not surprising that a dive computer like this doesn't have that feature. As for a digital compass, my Suunto has one but I find it a hassle to have to hold down a button to switch over and if you don't hold long enough to switch back, you get a new waypoint instead so I'll be getting a good old magnetic one to wear on my wrist as my MAIN compass. So much faster to just take a glance at your arm without having to press any buttons.

I never understood this.


Everything about Tec diving calls for redundancy. Why not a transmitter to act as back up to your spg? Seems to me a great way to find a back up for the most important part of diving... The breathing gas volume....

 

[uwxplorer]

Why not a transmitter to act as back up to your spg?

SPG's, plural. That would be the first question to address, cost-wise, reliability-wise, etc.

The second point is that a tech diver is supposed to plan his dive, dive his plan (not that this not part of the recreational mantra, but practically?), so gauge checking, while useful, is to some extent unnecessary or infrequent, as long as the dive goes as planned.

Third, there is much info reflected on the computer already, specially for rebreathers, so crowding the display with extra info which is not that critical, would be counterproductive.

And as mentioned, these things would have to withstand pretty harsh conditions, not just depth...

In principle, an exact knowledge of gas consumption would sound like a good piece of info to fine tune deco calculations. However, inferring gas inhaled from gas consumed is not really possible, as you could vent your loop, or flush it (speaking rebreather here), etc. Knowledge of the gas content is what matters most, and you do enter that manually (and for a rebreather, pO2 is read continuously in some configs, or assumed to be maintained by the divers in others).

So bottom line, there are very few advantages and quite a few drawbacks of adding this to a tech computer. At least, that's what I could imagine to be some of the reasons for SW not following in the tracks of Liquivision... But who knows? Never say never!

Disclaimer: I am truly novice in tech diving, but at least I do not dream of having all my tanks wirelessly connected to my Predator anymore

 

[Jim Lapenta]

Transmitters also have a second battery in them that can fail. The trasnmitters I have seen are all big things that can get bumped, tangled in something, and are expensive. They are also not needed. And it only takes one time for the signal to be lost at the wrong time or transmitter to fail and you are messed up or dead. It is not like an OW dive where if it fails you just go up, cuss it, take it off and put on the spg you should have been.using in the first place. You may not have the option to go directly up.
Sent from my DROID X2 using Tapatalk 2

 

[Omisson]

Transmitters also have a second battery in them that can fail. The trasnmitters I have seen are all big things that can get bumped, tangled in something, and are expensive. They are also not needed. And it only takes one time for the signal to be lost at the wrong time or transmitter to fail and you are messed up or dead. It is not like an OW dive where if it fails you just go up, cuss it, take it off and put on the spg you should have been.using in the first place. You may not have the option to go directly up.
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Again, so?

Yes a transmitter's batteries can fail. An SPG could get struck and fail, a dive computer could fail. My regulator could fail.

Because something COULD fail you wouldn't use it as a backup?

This is a logically inconsistent position.

Just saying.

 

[kelemvor]

I recently bought two petrel for cave diving. Have to say that I wish it had a transmitter capability as well. Primarily because I miss the data in downloaded logs.

 

[Omisson]

SPG's, plural. That would be the first question to address, cost-wise, reliability-wise, etc.

The second point is that a tech diver is supposed to plan his dive, dive his plan (not that this not part of the recreational mantra, but practically?), so gauge checking, while useful, is to some extent unnecessary or infrequent, as long as the dive goes as planned.

Third, there is much info reflected on the computer already, specially for rebreathers, so crowding the display with extra info which is not that critical, would be counterproductive.

And as mentioned, these things would have to withstand pretty harsh conditions, not just depth...

In principle, an exact knowledge of gas consumption would sound like a good piece of info to fine tune deco calculations. However, inferring gas inhaled from gas consumed is not really possible, as you could vent your loop, or flush it (speaking rebreather here), etc. Knowledge of the gas content is what matters most, and you do enter that manually (and for a rebreather, pO2 is read continuously in some configs, or assumed to be maintained by the divers in others).

So bottom line, there are very few advantages and quite a few drawbacks of adding this to a tech computer. At least, that's what I could imagine to be some of the reasons for SW not following in the tracks of Liquivision... But who knows? Never say never!

Disclaimer: I am truly novice in tech diving, but at least I do not dream of having all my tanks wirelessly connected to my Predator anymore

Taking away rebreather issues - I disagree that computer complexity is an issue, but screen information loading may be- Real time air consumption / air remaining in open circuit is most definitely NOT a minor advantage. It is a major one.

We can plan sac rates all we want, we can plan stop depths and ascent times all we want- sometimes reality gets in the way. Being able to REDUNDANTLY plan on the fly seems like a good idea to this Tec diver.

At least in OC if you can have a redundancy to your SPG why not use it? If it also can recalculate deco as a back up deco plan... Why not?

---------- Post added April 6th, 2014 at 11:50 AM ----------

Transmitters also have a second battery in them that can fail. The trasnmitters I have seen are all big things that can get bumped, tangled in something, and are expensive. They are also not needed. And it only takes one time for the signal to be lost at the wrong time or transmitter to fail and you are messed up or dead. It is not like an OW dive where if it fails you just go up, cuss it, take it off and put on the spg you should have been.using in the first place. You may not have the option to go directly up.
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Can you explain how you "are dead" because of using a transmitter as a back up if it has a failure in Tec diving?

I can't think of how this would happen if you are following the Tec rules.

A) I have a redundant computer
B) I have a written deco plan
C) I have a redundant bottom timer & actual uS Navy dive table with deco schedule
D) I have an SPG for tank volume
E) I have redundant air and used rule of 1/3rds
F) I have deco gases

Maybe you can explain to everyone how you wind up dead from a transmitter failure- because I can't.

 

[uwxplorer]

This is a logically inconsistent position.
Just saying.

Appearance can be deceptive
Seriously, read the previous posts again, without separating the factors. The weight is tilting the scale towards not bothering with wireless gauges.
Analog gauges fail, but rarely during a dive. And in technical diving, if you really don't know your tank pressure, you have bailout, so this is a non issue.
Getting it yet?

I understand your surprise though, because it was mine coming from recreational diving. But as you start planning ahead on how to deal with equipment issues and contingencies, you realize that simple and reliable is good; sophisticated and prone to glitches, an annoyance to avoid.
When they will be cheap, reliable and integrated in a 17' virtual head-up display, then maybe...

As a matter of fact, one of the rebreathers still on the market uses wireless HP gauges, and they are sources of trouble for their users.
I have a Datamask for my OC diving, and transmission gets interrupted at times; meanwhile, my hose-connected Cobra has never lost track of my tank pressure...
And last draw: I once asked a fellow diver to double-check my tank valve for me before jumping in the water: she handed me my wireless transmitter which she had mistaken for the tank valve! Lessons learned, AFAI am concerned.

In short, they are terrific tools, but don't have the favors of most tech divers for very good reasons. And again, being tech diving oriented, that is probably why SW doesn't use them in their tech computers.

Who knows, they might develop a recreational version with wireless transmission someday?

Safe diving!

---------- Post added April 6th, 2014 at 01:13 PM ----------

Maybe you can explain to everyone how you wind up dead from a transmitter failure- because I can't.

I don't think death is the concern... or not any more than each time you go underwater.


---------- Post added April 6th, 2014 at 01:33 PM ----------

. Being able to REDUNDANTLY plan on the fly seems like a good idea to this Tec diver.

This is fine when the transmitter works reliably. If it does go blink-blink (as they do), just imagine the added software complexity to take this into account. It should be able to switch back and forth between no transmitter data and transmitter data mode at all times. Considering to begin with that the current SW software does not take actual gas consumption into account, this would require a major redesign of the algorithm. And most likely plenty of bugs (some critical?) to deal with...
I've got an idea: why don't you send a feature request directly to SW and offer to volunteer as a beta tester?


PS: I can send you a dive profile from my Datamask that makes absolutely no sense because the transmitter was acting up. Then extrapolate at 200 ft with 1 hr of deco obligation (the kind of dive I am still far away from performing). I am not sure of the added benefit, really...

 

[Jim Lapenta]

Again, so?

Yes a transmitter's batteries can fail. An SPG could get struck and fail, a dive computer could fail. My regulator could fail.

Because something COULD fail you wouldn't use it as a backup?

This is a logically inconsistent position.

Just saying.

No I won't. I'm not.going to.waste money on a transmitter. It would be better spent on gas fills, dives, and training. If you want to use one go right ahead. Just don't expect me to. Ever. I am not in a position to waste money on technology that adds nothing to my safety or security. And in fact may add complexity with no added benefit.
I know my SAC rate, I plan my gas, but I also do not want to look at my gas supply monitor and see nothing. Doing that could make me question things at a time I don't need to be. That doubt is not worth the risk. I.don't.care if someone else wants to use. I won't dive with them. And they won't use one in any of my classes without a back up spg. And that is what they will use for planning.

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[Omisson]

No I won't. I'm not.going to.waste money on a transmitter. It would be better spent on gas fills, dives, and training. If you want to use one go right ahead. Just don't expect me to. Ever. I am not in a position to waste money on technology that adds nothing to my safety or security. And in fact may add complexity with no added benefit.
I know my SAC rate, I plan my gas, but I also do not want to look at my gas supply monitor and see nothing. Doing that could make me question things at a time I don't need to be. That doubt is not worth the risk. I.don't.care if someone else wants to use. I won't dive with them. And they won't use one in any of my classes without a back up spg. And that is what they will use for planning.

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Ok I get it- YOU think they are too expensive. And YOU won't dive with someone who has one. Again ok- your prerogative.

But- you dodged the question. YOU said a transmitter failure can kill you.


Please explain How can a transmitter failure kill you in Tec diving - IF you are using it as a redundancy and are properly following Tec diving redundancy procedures?

You can't - because there isn't a way. You said something without any sort of logical rationale to drive home YOUR personal preference-and with disregard for the fact that as an instructor you should be able to separate objective fact from personal preference.

This is the problem with many instructors and divers... Actually With people today in general. "Because I said so" WITHOUT a rationale is not a sufficient reason to discount a practice. Moreover, it is even worse to base a bully pulpit speech on.

Now I've heard lots of good reasons for not relying on a transmitter in a Tec environment as a primary methodology. I agree. But as a redundant/back up datapoint that can give you hard useful data after a dive? Nothing I've heard or seen contraindicates it's use, except of course, "because I said so".

Facts are stubborn things... You are entitled to your own opinion but not your own facts.