Shearwater Perdix AI

[Diving Dubai]

Suuntos and Liquivision have the lazy implementation of air time that does not include ascent time. Oceanic and Uwatec include ascent time.

I can't speak for all Suuntos, but can assure you that the Eon takes into consideration ascent time and all stops with its GTR

 

[stuartv]

They use a PPS transmitter and computer hardware, I'm hoping they use the GTR algorithm that in includes the ascent, like I'm very accustomed to with Oceanic

Me, too. But, I have never been concerned with how my Oceanic computer calculates GTR once you go into deco and have a second gas configured. I would never use my Atom as my primary computer for that kind of dive. It's a much more realistic question, though, with a PAI.

But, based on a graphic that @kelemvor posted, it is now my understanding that the PAI GTR calc is based solely on the gas that you are currently using. So, I would expect (just expect, mind you) that the GTR will include total ascent time, including deco stops. But, GTR will be useless if you're doing a deco dive where you will be using a second gas for accelerated deco. Which is fine. Nobody doing accelerated deco dives should have any need or use for a GTR display on their computer.

Arguably, nobody that is doing backgas-only deco diving should have any use for a GTR display, either. But, I kind of feel like if you buy into that logic, you would have to carry it further and conclude that nobody should have any use for an NDL display, either. I mean, if you trust your computer to calculate your inert gas tissue loading, don't you think you can trust it to monitor your tank pressure and calculate how long until you have to start your ascent? But I digress...

 

[guyharrisonphoto]

Amen to this for recreational diving. I am used to the GRT taking the ascent and safety stop into account so I reach the surface with a pre-set reserve, as my Galileo does. Overall, I find the Uwatec GTR algorithm very accurate and useful.

 

[Diving Dubai]

GTR in my opinion is a pointless feature, and one that could cause the inexperienced diver to be lulled into a false sense of security. GTR is normally calculated using your current consumption rate. All well and good, but if you use it to push the limits of the dive and then get a situation where you suddenly get elevated consumption, then it's highly possible you'll have got yourself into an OOA situation.

GTR in my opinion is no substitute for gas planning.

I've used it once, when in a difficult situation with a current, and a massively elevated SAC rate, I referred to it while weighing up my options, even then only to double check my mental calcs.

As far as I'm aware all computers with GTR ot TTD (timer to die) as I like to call it, just work on the selected gas. I don't know of any that can take into consideration other gasses and come up with an overall total

 

[admikar]

GTR in my opinion is a pointless feature, and one that could cause the inexperienced diver to be lulled into a false sense of security. GTR is normally calculated using your current consumption rate. All well and good, but if you use it to push the limits of the dive and then get a situation where you suddenly get elevated consumption, then it's highly possible you'll have got yourself into an OOA situation.

That was what I was trying to say.

 

[scubadada]

Amen to this for recreational diving. I am used to the GRT taking the ascent and safety stop into account so I reach the surface with a pre-set reserve, as my Galileo does. Overall, I find the Uwatec GTR algorithm very accurate and useful.

GTR in my opinion is a pointless feature, and one that could cause the inexperienced diver to be lulled into a false sense of security. GTR is normally calculated using your current consumption rate. All well and good, but if you use it to push the limits of the dive and then get a situation where you suddenly get elevated consumption, then it's highly possible you'll have got yourself into an OOA situation.

GTR in my opinion is no substitute for gas planning.

I've used it once, when in a difficult situation with a current, and a massively elevated SAC rate, I referred to it while weighing up my options, even then only to double check my mental calcs.

As far as I'm aware all computers with GTR ot TTD (timer to die) as I like to call it, just work on the selected gas. I don't know of any that can take into consideration other gasses and come up with an overall total

I have 1200 dives on DSAT and Oceanic GTR. I am in agreement with @guyharrisonphoto , for rec diving, the calculation , in general , is extremely accurate. Of course, I relatively routinely ignore the dive time of zero on my drift dives in SE FL and surface with less than 500 psi. @Diving Dubai is quite an advocate of Suunto, appears he cannot endorse their GTR algorithm. Of course, extraordinary circumstances might interfere with this calculation in any application. If something changes significantly, of course you make corrections, duh. I hope the Perdix AI uses the Oceanic iteration of GTR

 

[TulsaTime]

the only reason someone would have for going with something else is if they really want a wristwatch-sized computer.

There may be another reason - I know they're not generally well received here on SB but the Liquivision setup allows you to see up to 9 additional transmitters as well as your own. My son and I both have them and we can see each other's air and know where we each are (airwise) without having to signal back and forth. Also, there's the issue of range with the ultrasonic vs radio transmitters which is what allows the Lynx to provide the (admittedly questionably useful) locator feature.

Now, if Liquivision would only release the Omnix and update their dive log software...

 

[scubadada]

I have no need to "see" my buddies air, thanks

 

[TulsaTime]

And you have no "need" to see your own air on a wrist computer when a standard analog SPG works just fine, too. We're talking about niceties, not necessities.

 

[Bnizzle]

I literally just bought a Perdix less than a month ago