Figured out the Suunto Vyper Air issue my LDS talked about...

[D_B]

Seeing as this is in the Basic Scuba forum, I'm going to mention here that unless you have picked an air reserve based on planned depth and an amount enough to share with your dive buddy and get all the way to the surface safely, the "air dive time remaining" indication on an air integrated computer is not really the one you should be going by

If you want to know more about it, look here ... http://www.scriptkiddie.org/blog/2010/09/19/rock-bottom-and-gas-management-for-recreational-divers/ ... I use Lamont's easily remembered rule of thumb for my purely OW diving
Or look for information on "Rock Bottom"

 

[Hatul]

Seeing as this is in the Basic Scuba forum, I'm going to mention here that unless you have picked an air reserve based on planned depth and an amount enough to share with your dive buddy and get all the way to the surface safely, the "air dive time remaining" indication on an air integrated computer is not really the one you should be going by

If you want to know more about it, look here ... http://www.scriptkiddie.org/blog/2010/09/19/rock-bottom-and-gas-management-for-recreational-divers/ ... I use Lamont's easily remembered rule of thumb for my purely OW diving
Or look for information on "Rock Bottom"

To use the "Air Time" you really have to know how it's defined for your particular computer. I think for Suunto it means the amount of time you have to stay at depth to reach reserve at the current air consumption.

At a particular depth it takes depth(in feet)/30 minutes to reach surface aside from safety stop. Also, a safety stop uses about 150 psi with al80, so for two it's 300psi.

A simple rule of thumb (Imperial units):

Set reserve at 650psi. So at safety stop you'll go down to 650-300 or 350psi.

Then at each depth divide the depth/30 and require the Air Time to be at least twice that. That should get you enough time to swap regs and allow an ascent to surface with elevated air consumption due to stress.

So say you're at 60 ft with your buddy, start your ascent no later than when Air Time is 4 minutes.

At each depth you should quickly work out how much air you need for both of you to make a safe ascent and make sure you're above that. The AI computer makes this easier because all the numbers you need are there in one place.

Adam

 

[Atom]

Seeing as this is in the Basic Scuba forum, I'm going to mention here that unless you have picked an air reserve based on planned depth and an amount enough to share with your dive buddy and get all the way to the surface safely, the "air dive time remaining" indication on an air integrated computer is not really the one you should be going by

If you want to know more about it, look here ... http://www.scriptkiddie.org/blog/2010/09/19/rock-bottom-and-gas-management-for-recreational-divers/ ... I use Lamont's easily remembered rule of thumb for my purely OW diving
Or look for information on "Rock Bottom"

Good point, but you make this feature of the computer work for you if dive RB. You simply have to figure out your rock bottom pressure before the dive and set it as your tank pressure alarm. And since the air time is the time till you hit your tank pressure alarm, it'll indicate how much time you have before you should head up.

Of course if you're doing a multi-level dive going from 30m/100' to 10m/30' you'll want to approach this a bit differently, since your rock bottom at 100' is very different than your rock bottom at 30'.

 

[D_B]

Just wanted to bring the subject up , you already have a grasp at what I'm referring to

On the fly recalculations is why I like Lamont's Rock Bottom rule of thumb ... (for my steel HP 100 tank thats add a 0 to your depth plus 300 = psi needed to start ascent ... Example: 60 feet plus a 0 = 600 + 300 = 900 psi to start ascent with enough reserved air for you and buddy) this works fine for reasonable depths/tank size/OW

 

[NCadiver]

@ Ncadiver: Before I even bought the comp, I read the online manual, posted ?s here about it, asked 4 different LDSs, even called Suunto support on this very issue and no one had an answer so due diligence was taken. There is nothing in the manual that indicates that the channel that the transmitter selects can be reset by an abrupt pressure introduction which is what seems to be occurring (I'll play with this some more once I get my tanks back). All I could find that is remotely in line to this was: "Slowly open the cylinder valve fully and pressurize the regulator. The transmitter starts transmitting when the pressure exceeds 15 bar/218 psi."

But feel free to prove me wrong: http://www.opensea.ru/_data/documents/0000447/Instr_Suunto_Vyper_Air_eng.pdf

As I indicated above, this is not really a normal situation and won't warrant discussion in the manual...but it happens. So far, the transmitter has stayed on the same channel as I don't blast open my tanks.

Page 18 of you manual. The manual tell you tha it change channels, And if they are out of air what does it matter I think getting air would be the priority. I know you are new but you need to understand the manual and the computer. And that LDS of yours does not know what he is talking about so don't get your information from them and find a new LDS. The Vyper air is base off the D9 and Vytec which has been around for over 10 years.

 

[Hatul]

Hi Atom,

Your rule would work and uses the Air Time as a simple countdown timer. The problem is as you point out on a multilevel dive it would not work. Also for each dive you have to calculate your reserve, and also with a high reserve you run into alarms when your air time goes to zero.

With my Air Time = 2 * ascent time rule you always set your reserve to 650 psi and it works for multilevel as well.

D_B,
I like that rule when you don't use air integration. When I looked at it my constant was bigger than 300. It was
400 + 10 * depth for 100HP
500+ 10* depth for Al80
600 + 10* depth for HP80
Maybe mine is too conservative. Next time I'll look at this on a dive and compare to my Remaining Bottom Time rule with the Galileo Sol.

Adam