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John Henry
06-28-2009, 08:19
Just did my first diving using Nitrox. Throughout the dive, the O2 % was continuously displayed (32) and flashing in the bottom left corner, where Tank Pressure is normally displayed.

I thought this was odd, because I dont need to know O2 % every time I look at the computer, (It doesnt change, and I set it, so why display it?) I need to know tank pressure. To get tank pressure required paging through three displays each time.

Reading the manual, this seems to be normal. I think it is stupid.

Did I miss a step somewhere? I need to see tank pressure, not O2 % .

Any help?

cbope
06-28-2009, 10:44
Actually it is important, as most Suunto's like your Cobra 2 support multi-gas switching (2 gases if I remember correctly). It could lead to DCI if your computer "thinks" you are using a particular mix but in fact you have a different mix in your tank. So for that reason alone it's a good idea for the computer to show your mix on the main screen so that you KNOW which mix is being used for NDL caluculations (and resulting deco stops if you are deco diving).

I haven't used my D6 for mixes other than air since I got it but I'll check to see if it does the same thing. Of course the D6 doesn't support air integration so I think that other Cobra owners will have to chime in.

John Henry
06-28-2009, 11:01
yes, you are correct about setting it up for two gases. But I still would rather see tank pressure than mix %.

Maybe that's just me, since I am a relatively new diver.

Diver Dave
07-13-2009, 19:23
I would re-read the manual. I dive an air integrated Cobra 2 on Nitrox almost exclusively (28%-32%) and have never experienced this. Try manually setting your pp02 level warning function (I use 1.4 ata) and see if that doesn't solve the prolem.

Jack Hammer
07-14-2009, 00:04
I use a Gekko, mine shows the % always when in nitrox mode, they did this so you would know what gas you are breathing (or what you told the computer you are using). This is actually a good thing, a few times I forgot to set the % and noticed it as soon as I got ~5' down, I just surfaced and set it for what I was actually breathing.

After a while you get used to the different screen layout. One of my buddies used the cobra and IIRC you can hit one of the buttons to toggle to pressure, there might even be an option in the menu.

Jack

RogerAg
11-05-2009, 17:51
I have both a Cobra 1 and a Cobra 2. I never would have upgraded to a Cobra 2 if I know the problems with it in Nitrox 2 mode. When I dive I usually do a 2 or 3 tank dive and usually the last tank is Nitrox. So the Cobra 2 and mode 2 I thought was a good idea. In mode 2 I would have mix 1 at 21% and mix 2 set at the percentage of the last tank, usually around 32%. But in mix 2 the Cobra does not show tank psi. What it does show is the mix FLASHING such as 32%. I keep my Cobra console next to my chest usually facing me so I can see depth and tank psi at a glance. What I don't need to see is a flashing 32%, for Gods sake I know what percent oxygen I have because I entered it into the Cobra, what I don't know is what the tank pressure is. I really think that tank psi is more important information then oxygen percentage because that does not change but psi does. Some people say that it is a good thing to see the % of gas you are breathing and I say YES but once I see it I don't need to see it throughout the dive. What we should have is psi showing all the time and toggle to % if I want to make sure but then the computer should always go back to psi.

nrembis
11-05-2009, 18:16
I might be overlooking something, but but switching to another gas, wouldnt matter what your psi is showing on the computer as its another tank

RogerAg
11-06-2009, 17:59
Cobra 2

The real problem with the Cobra 2 is it is my opinion that it was misrepresented by Suunto. The Cobra 2 is advertised as “2 gas switching” but what Suunto does not say is what “2 gas switching” means.

When I dive I usually do my deepest dive first and I use Air.
On the second dive of the day I will usually use NITROX, which helps me to offgas, and I don’t usually fall asleep in my chair while watching TV in the evening, that is probably why they call NITROX “geezer gas.”

In the Cobra 2 User’s Guide it states that if the Cobra 2 is set at AIR then you can not switch to NITROX within 24 hrs. So since I use AIR on the first dive and NITROX on the second dive, the Cobra 2 is set on NITROX and the O2 is set at 21% which is the same as AIR.

The Cobra 2 has two (2) NITROX settings called “MIX 1” and “MIX 2”. And the Cobra 2 allows the diver to switch from “MIX 1” to “MIX 2” while on the surface or underwater. So I set the O2 “MIX 1” at 21% and “MIX 2” is set at the dive shop after I test the O2 of the tank which is usually 32%. This is quite convenient because I don’t have to enter new values on the Cobra 2 while on a pitching boat with the sun glaring down on the display.

The Dive

On dive 1 of the day I usually hook up my tanks myself. When done I check the tank psi then I turn the air off and take note of air leaks. When I’m ready to dive I turn the air back on, put on my gear including BCD do a buddy check and jump in the water while on the surface I do another check psi OK, Cobra 2 OK and BCD OK. As I descend I am always watching depth and psi. While in “MIX 1” the Cobra 2 works as expected.

After surfacing and back on the boat I hook up the NITROX tank and I switch to “MIX 2” which was preset at the dive shop, lets say O2 32%, then I do all the pre checks that I did on “dive 1”. On the boat and while floating on the surface the tank psi continues to show psi BUT when descending below 10 feet the Cobra 2 in “MIX 2” stops showing psi and only shows O2 32% in the place of psi.

Now I can switch under water from “MIX 2” to “MIX 1” and psi comes back and stays but the Cobra 2 now thinks that I am now at 21%. I can also switch from O2 32% to psi but only for 2 seconds and then the Cobra 2 go back to O2 32% and stays there until I surface. That’s right when I get above 10 feet psi comes back and O2 32% goes away!

My dive shop sent the Cobra 2 in for repairs and it came back as OK!
After my next dive I when back to my dive shop and they sent the Cobra 2 back in for repairs. It came back as OK! and this time they included a new User’s Guide!
This time I used the dive shop pool to check the Cobra 2 and the same thing happened, on the bottom of the pool (10 feet) “Mix 2” no longer showed psi but O2 32%. Then the Dive Shop owner took my Cobra 2 to the bottom of the pool and when he came back up he immediately called his tach at Suunto. As it turns out his tach is not the same as a users tach. My dive shop owner was told that the Cobra 2 is doing just as its supposed to do. “Mix 2” is used when a 2nd tank strapped to the divers side such as a deep dive when the 2nd tank is used for decompression.

“Mix 2” is used when the diver is breathing off of a second tank of air while the Cobra 2 is attached to the empty tank while decompressing.

The problem is that the dive shop does not know that because the “User’s Guide” does not say that! BUT the “User’s Guide” on page 6 does say “WARNING NOT FOR PROFESSIONAL USE! Suunto dive computers are intended for recreational use only.”
That is why I say that the Cobra 2 is in my opinion misrepresented by Suunto. I would not have paid as much as I did for the Cobra 2 because there are other problems that I did not mention.

nrembis
11-06-2009, 18:19
I would say you better find you a new dive shop/instructor before someone gets killed

any competent instructor/owner/salesman would have known that the 2 gas mixes on the Cobra 2 are settings for a deco mix during same dive, I dont think suunto mis-represented it, its just a matter of lack of education on someones part.

thesmoothdome
11-06-2009, 20:36
It's always been my understanding that a computer that does 2 mixes means that the switch is done during the dive. If you start a dive with 21% that would be Mix 1. If you switch to a higher O2 during a shallower part of your dive or for deco purposes, that would be Mix 2.

Sounds like it's a lack of understanding of the usage of computer able to switch gases rather than a misrepresentation by the company.

Jack Hammer
11-07-2009, 11:29
RogerAG, as mentioned above a multigas computer (2 gasses or more) allows a diver to switch gasses underwater. This feature isn't just used by commercial divers, but also by technical divers or a diver using stages. It's a feature that you don't have to use but is nice if you ever progress to a point where you might use different gasses on one dive.

As far as being able to change you mix between "air" and nitrox, just set the computer to Nitrox for all dives and when using air set the percentage to 21%. "Air" and 21% nitrox are the same thing and using a 21% nitrox setting will give you the same NDL's as having you computer set to "Air." This will allow you to adjust the percentage to a higher mix when needed.

RogerAg
11-07-2009, 16:37
The only place I found the words 2 gas switching was on the web telling about the Suunto Cobra2 and it states:
"Electronic compass and tilt sensor
Matrix display
2 gas switching
Optional Deep Stops
Dive profile displayed graphically on the screen
With two-gas switching Nitrox, Air, and Gauge modes, this air-integrated computer delivers everything you need to maximize bottom time and make the most of every dive."

Nowhere in the Cobra2 "User's Guide" does it use those words. Not in my OW dive manual and NITROX dive manual and Advanced dive manual is that term used! I also have "The Encyclopedia of Recreational Diving" and the term "2 gas switching" is not used! So were is it?

When I called Tach Support about the problems I was having I was told many things such as I violated my OLF and another time I violated my PO2 in fact I got a different answer each time. I know that I had not violated my OLF or PO2 because of the circumstances for those dives. I was certified for NITROX in 1998 but I did not get my first NITROX dive computer until April 2002 which at that time I had 162 dives so I know how to use the NITROX dive tables. Then I put over 500 dives on my Cobra1 (Wonderful Dive Computer) Now I have a 31 dives on the Cobra2 and I HATE IT! Its hard to use and is not user friendly like my old Cobra1.

I called Tech Support many times and they did not know the answer. And I sent the Cobra 2 in for repairs twice (2) explaining what was wrong and they did not have the answer, only that the Cobra2 was OK! So how do you expect a dive shop/instructor to have the answer?

And you are correct when you said that someone could get killed. But not me (at least for that reason) because I know the answer that is not in the User's Guide! TURN OFF MIX2

But what about Divers like "John Henry"
The fault lies NOT on dive shop/instructors or NOT reading the User's Guide, the fault lies in the User's Guide itself.

You are might be wondering why I bought a Cobra2 when I was happy with my Cobra1? Well it was my wedding anniversary, we were in Hawaii and I FORGOT!!!!!!!!!! My wife wanted the Cobra2 so what Patty wants Patty gets! Well Patty hated the Cobra2 she said that it was too hard for her to use and Patty wanted to trade FOR MY COBRA1. You all have to know that IF PATTY AINíT HAPPY NO ONE IS HAPPY! That's how I got the Cobra2

All I wanted was to exchange the Cobra2 for a Cobra1 but Suunto said NO! So much for their support!

thesmoothdome
11-08-2009, 15:59
And you are correct when you said that someone could get killed. But not me (at least for that reason) because I know the answer that is not in the User's Guide! TURN OFF MIX2

But what about Divers like "John Henry"
The fault lies NOT on dive shop/instructors or NOT reading the User's Guide, the fault lies in the User's Guide itself.


I became interested in what was said in the user guide so after a quick read, here is what it says:


6.2.4. Gas change and multiple breathing gas mixes

The Suunto Cobra2 allows gas changes to enabled gas mixes during the dive. Gas changes
are made by following the procedure below:



CHANGING GAS MIX. SCROLL
THROUGH ENABLED MIXES BY
PRESSING THE UP OR DOWN
BUTTONS. SELECT NEW MIX BY
PRESSING THE SELECT BUTTON.

NOTE Mix number, O2%, and PO2 for the mixes are shown when scrolling.
If the set PO2 limit is exceeded , it will be shown with the PO2 value
blinking. The dive computer does not allow you to change to a gas
whose set PO2 is exceeded. In such a case, the mix is shown but
cannot be selected.

NOTE If no button is pressed in 15 seconds, the dive computer will go back
to the dive display without changing the gas mix. Upon ascent, the
computer prompts you to change gas when the PO2 level you have
set for the next mix allows a gas change. The prompt is an audible 3
beeps and the current O2 mix starts to blink.


I understand that you're not happy with the Cobra 2 and it's a little more complex than you would like, but the purpose of the 2nd mix is pretty clearly explained here.




[quote=RogerAg;346029

All I wanted was to exchange the Cobra2 for a Cobra1 but Suunto said NO! So much for their support![/quote]

Why would Suunto exchange it? Did you attempt to exchange it at the dive shop you purchased it from?

RogerAg
11-13-2009, 18:00
Hi thesmoothdome
You are correct and I did miss that "During the Dive' and thanks for taking the time to point that out.

Did you also notice that on page 6 it says: Warning NOT FOR PROFESSIONAL USE! Suunto dive computers are intended for recreational use only. Now back when I first got certified Switching tanks underwater was not recreational. Has that changed?

Granted I don't like my Cobra2 but if it had one (1) feature, yes just one that is not there at this time I would have been proud to be a Cobra2 user. That one feature that is not on the Cobra2 is; I would love to see tank psi on the screen. For some reason Suunto decided that displaying tank psi (which goes down during a dive) was not important but continuing to display O2 was (which stays the same).

thesmoothdome
11-13-2009, 21:11
Hi thesmoothdome
You are correct and I did miss that "During the Dive' and thanks for taking the time to point that out.

Did you also notice that on page 6 it says: Warning NOT FOR PROFESSIONAL USE! Suunto dive computers are intended for recreational use only. Now back when I first got certified Switching tanks underwater was not recreational. Has that changed?

Granted I don't like my Cobra2 but if it had one (1) feature, yes just one that is not there at this time I would have been proud to be a Cobra2 user. That one feature that is not on the Cobra2 is; I would love to see tank psi on the screen. For some reason Suunto decided that displaying tank psi (which goes down during a dive) was not important but continuing to display O2 was (which stays the same).

I just did a quick search of a few other dive computer manuals and they all state in some way shape or form that the computers are not meant for commercial diving. A lot has changed since I was certified. Split fins didn't exist, purge valves were still in fashion and Nitrox was considered "tech diving" and computers only did air profiles. There's no doubt that the line between rec and tech has moved as technology has evolved. Just like everything else in diving, it's important to stay within your comfort level and your training. Changing mixes during a dive doesn't necessarily mean you're a tech diver.

As for the O2 display, I found this on page 32 next to the pictures detailing each screen:


DOWN BUTTON
TOGGLES
BETWEEN O2,
MAXIMUM DEPTH
TANK PRESSURE
AND CURRENT
TIME.

Hope this helps.

RogerAg
11-14-2009, 11:08
Hi thesmoothdome

I think your missing the main point that I don't like about the Cobra2. When in Mix2 it does not continuously show tank psi during the dive.

But lets start at the beginning of the dive on the dive boat.

In this case scenario I'm in Hawaii on a dive boat.
While still on the dive boat when the Cobra2 is hooked up to the tank and turned on; Tank psi continuously shows at lower left hand side. Everything appears to be OK!

We are asked to jump in the water and wait on the surface till everyone is in the water and all signals OK! On the Cobra2 Tank psi continuously shows up at lower left hand side. Everything appears to be OK!

The signal to descend is given and everyone starts to descend. As I go down all seems OK until I go past 10 feet, then tank psi goes away and the Cobra2 continuously shows up on the lower left hand side O2! Tank psi is now GONE!

During the dive the Cobra2 continuously shows O2 on the lower left hand side.

Nearing the end of the dive at the safety stop 15 to 20 feet the Cobra2 continuously shows O2 on the lower left hand side. Still no tank psi.

Ascend above 10 feet and O2 goes away and tank psi continuously shows on the lower left side.

Back on the boat I tell the dive master and skipper that the Cobra2 does not show tank psi during the dive. They check it out and there it is tank psi continuously showing!!!!!!!!!

And then they all move away from me on the bench, looking at me with hairy eyeballs thinking I'm someone that didn't read read his user's guide!

RogerAg
11-14-2009, 11:54
Hi again Hi thesmoothdome

It took me awhile to figure out how to get a photo of me on this website. This one I call Braindrain.
I noticed that you also have "my Photos" How did you get that?

I see that they have me listed as "TadPole" I've been south of the equator so I'm no longer a Pollywog.

Jack Hammer
11-14-2009, 19:32
RogerAG - Commercial use refers to a paid "professional," the recreational use moniker actually covers technical diving, unless it is done for a living. Think of multigas diving as more advanced recreational diving.

Not sure about your specific model but some computers will give you the pressure for multiple tanks. However, for this to work you would need a pressure sending unit on each tanks first stage regulator. This really wouldn't work for you because you'd have to change your sending unit with each tank change.

As I recommended before, I think the best solution for you is to leave your computer in Nitrox mode at all times and set the mix for 21% when you use air. Then you can easily change the mix between dives to meet your tank contents. This is how I've been using my Gekko for the past two years and it works fine. As far at the two gas switching goes, just don't use it and you'll be fine. (if you get into planned gas switch diving at somepoint you will be ahead of the game.)

RogerAg
11-15-2009, 11:12
RogerAG - Commercial use refers to a paid "professional," the recreational use moniker actually covers technical diving, unless it is done for a living. Think of multigas diving as more advanced recreational diving.


As I recommended before, I think the best solution for you is to leave your computer in Nitrox mode at all times and set the mix for 21% when you use air. Then you can easily change the mix between dives to meet your tank contents.

I Got Paid one time to get a boat motor off a lake bottom so I suppose I am a "professional"

Did you notice that when I first replied in this thread that I stated:
When I dive I usually do a 2 or 3 tank dive and usually the last tank is Nitrox. So the Cobra 2 and mode 2 I thought was a good idea. In mode 2 I would have mix 1 at 21% and mix 2 set at the percentage of the last tank, usually around 32%.

But one problem is; it is NOT always when you say "Then you can easily change the mix between dives to meet your tank contents."
Because The sun is up and my eyes are tired and the boat is sometimes full and rocking. As I stated Mix 2 can be set at the dive shop were there is NO SUN GLARE

The problem is the design of the Cobra2 "In Mix 1 the Cobra2 will show tank psi and in Mix 2 it will not. WHY DESIGN IT THAT WAY???
But there are several ways to get around it. One way that I only did one time is: One the second dive after getting in the water. (I can see just fine underwater, no glare, no boat rocking, no crowed and everything is 20% bigger. The Cobra 2 lets you change mix 1 underwater!!
But remember this thread is about John Henry a newbe that didn't understand why his Cobra2 would not show tank psi.
However the Cobra2 has may problems and we only discussed ONE!

thesmoothdome
11-15-2009, 11:21
Hi thesmoothdome

I think your missing the main point that I don't like about the Cobra2. When in Mix2 it does not continuously show tank psi during the dive.



When you switch to Mix2, the computer has decided that you are on a different tank than the one you've hooked up to your main tank for which it reads PSI. Since it's a different tank, it wouldn't be reading PSI but would continue to track nitrogen absorption based on your settings for Mix2. Consequently, the computer switches to more important information, which in this case is your 02%. It's a good reminder that if you change mixes, you're changing your nitrogen absorption. Plus, since you're on a different tank, it could be downright dangerous to continue to show the PSI of a tank you're no longer breathing from. It's a much better reminder that you're not on that tank than to continue to show the PSI from a tank you're not currently breathing from.

As Jack mentioned, some AI computers can do multiple tank PSI, but with the Cobra II, that is not the case. In order to use the gas switching feature, you'd have a seperate regulator set up complete with pressure gauge on the tank containing Mix2.

On a separate note, you can add a signature line by going to the User Control Panel and clicking on "signature."

RogerAg
11-17-2009, 14:25
Hello Terry

Your statement “ It's a good reminder that if you change mixes, you're changing your nitrogen absorption.” Is valid however since now I have to add the o2 mix 3 to 4 hrs after testing the tank I have to remember what the mix is. I solve that problem by writing the mix and my name on some tape and I tap it to the tank. But it would have been easier to enter it into the Cobra2 at the time I test the o2.

Its interesting to note that tank psi continues to be shown on the Cobra2 but you have to search for it and after you do it only shows up on the screen for 1 or 2 seconds then it reverts back to o2.

Now I can change,
Time from 12hr to 24hr
Alarms on or off
Feet to meters
Bar to psi
Altitude adjustment 3 ways
Personal adjustments 3 ways

Why did they design the Cobra2 to only show o2, I should be able to do it my way.

When we got the Cobra2 I was really surprised to learn that it operated completely different from the Cobra1.

I noticed that in your profile it list that you dive with a Cobra, is it the Cobra1 or Cobra2?

Unhappily we lost some features that I have been enjoying when I started using the Cobra2, such as “average depth.” I was also surprised to learn that Suunto left out of the User’s Guide the “modes and operations” that is found on the inside back cover of the Cobra1 instruction manual. Suunto also included that same “modes and operations” on a plastic card that even can go underwater. BUT NOT the Cobra2. After more then 500 dives on the Cobra1 its was hard to learn a whole new computer.

By the way did you see the photos that I left on this site?
I was wondering how to remove one of them. It seems that it got posted twice.