Sunnto lockouts?

[jana]

Hi all,

I've basically decided on a Suunto Cobra--mainly because if I get a wrist mount, I don't think I'll check my tank pressure as much as I should!

I've got one question that I haven't been able to find an answer to: do the Suunto computers (or the Cobra specifically) have the "feature" of locking you out if you miss a deco stop? I know that the Cobra's not intended to be a deco computer, but this just sounds like a silly quirk that could ruin your whole day.

Any opinions, or comments on other odd behavior?
thanks!

 

[TexasMike]

Most computers will lock you out if you blow a stop. Remember, this is considered a safety feature since even if you blow a short and shallow stop, the chance of a DCS hit is increased.


With regards to "I don't think I'll check my tank pressure as much as I should", I find that as a more experienced diver (45 dives) I am not fussy about always checking my tank pressure. As I gain experience, I am getting a feel for how long an AL80 will last me at a given depth based upon good conditions (being warm and no current). So now I am more apt to check my watch/bottom timer, than I am my pressure.

Essentially I check when I hit my planned depth, then about every 10 minutes or so after that. And I like my computer on my wrist because I'm more apt to hit my NoDecoLimit before air is a concern.

Now, don't get me wrong, the Cobra is a air integrated good computer, but you will probably find that as your comfort level increases, you will gain the ability to "mentally" keep track of whats up with your tank.

 

[BillP]

Hi jana:

As I'm sure you realize, there's much more to selecting a computer than deciding how you're going to mount it. Computers (and dive tables) use mathematical algorithms to try to determine how much nitrogen you've absorbed on a dive. These algorithms have limits beyond which they "decide" you've made an unsafe dive and are at increased risk for developing decompression sickness (DCS). Sure the limits can be viewed as more or less arbitrary, but it doesn't matter if you're diving with a computer, tables, or making up your own decompression schedule in your head as you go along- you're eventually going to reach a limit beyond which you think you've made an unsafe dive and are at risk for DCS. If you have made an unsafe dive and are at increased risk for DCS it can take 24 hours (or more) for the symptoms to develop, so you should stop diving after any unsafe dive. You should "lock out".

What's an unsafe dive? Well that's where you use your training, experience, and knowledge to decide what level of risk you're willing to assume. Dive computer manufacturers also have to decide what they consider an unsafe dive and what level of risk they are willing to assume. People often don't think of this when they select a dive computer (or whatever decompression algorithm they're going to use) but I think it's one of the most important points of the decision making process. You MUST select a computer that has an algorithm that matches the level of risk you are willing to assume. If you buy a computer with too conservative an algorithm, you'll be displeased with the limits it places on your diving. If you buy a computer with too liberal an algorithm you might assume a level of risk that you didn't intend to.

Suunto computers are generally considered to have conservative algorithms. Depending on the dive profile, they might give you less dive time but an increased margin of safety. They do lock out when you violate their algorithms. (As any computer should IMHO.) If you don't think your diving style will allow you to dive a Suunto computer's algorithm without going into mandatory decompression status and then ignoring its decompression warnings- then you need to buy another computer that has an algorithm that suits you.

Just my 2¢,

Bill

 

[The Chairman]

Hey Jana & all...

I dive with a Cobra and love it... It gives me all of the info I need and has yet to lock me out. That is probably because I dive conservitively and do NOT push it. If I was locked out by my trusty Cobra, I would listen to it and wait until it was ready to get wet again. It has yet to let me down, I will listen to my buddy!

Personally, I have a hard time with ANYTHING on my wrist. Even a watch is a bother. The only time a wrist mount would be useful for me, would be on ascent. I may even purchase a Stinger which is fairly small to back up the Cobra and give me that additional function.

:tease:

 

[jana]

BillP et al,

I think that I'm concerned about being locked out because I'm not used to diving with a computer and I don't have a good feel for what might trigger it. I've been around plenty of divers who raise their arm too quickly and set their computer beeping--if a small event like that happens at just the wrong time, can it cause your computer to lock you out?

From what I've read about the different computer models, the RGBM that Suunto uses seems to be one of the newest. It being more conservative than some is definately okay with me, just so long as it's taking the whole dive profile into account, not little twitches.

Thanks for all of your comments!

 

[TexasMike]

All computers do take the entire dive into account, including the "little twitches" as you say, but these twitches don't overly influence the computed and displayed results.

The beeping is the audible ascent alarms. And hose mounted systems will do it too if you move them fast enough.

Finally, please note that the lock out will most likely occur if you are 1) diving deep enough and at that depth long enough to require a deco stop and 2) you blow the stop completely. My current diving style keeps me above 100 feet depth. And more than once I have seen my computer (Genesis ReACT) flip over to deco status (at a 10-foot stop) after being between 80-90 feet for a while. But when I return to shallower depths (say 60 feet), the computer will give me credit for being at the shallower depth and remove the deco stop requirement once sufficient "shallower time" has elapsed.

However, I do follow the safety procedure of a 5 minute safety stop at 15 feet if I go below 60 feet. And I add an extra 3-5 minutes if my computer flips over to deco status.

Please note that your mileage may vary, and I encourage you to be extraordinarily safe whenever your computer displys a deco state or any violation.

 

[Sue]

Jana

Cobra will only lockout if you disrespect one instruction (such as missing a deco stop or going above the ceiling in a deco stop) for more than a certain time - it bEEps and allows you to re-descend to perform the deco.

It doesn't lock if you miss a safety stop (recommended but not mandatory).

And even when it does lock it keeps on giving you the depth, dive time, and remaining air time.
Cobra is a great option.

Sue

 

[Warhammer]

Jana.....In reference to the new Suunto computers there are 3 different types of stops. They are a recommended safety stop, mandatory safety stop, and a decompression stop.

A recommended safety stop will be applied to every dive by the Cobra. If you choose not to do it, no big deal, but the Cobra may choose to penalize your NDLs on subsequent dives.

You'll get a mandatory safety stop if you ascend to fast for too long. You'll see the STOP symbol come on, arrows will appear between the depth readings (which arrows depends on your depth), and the Ceiling symbol will appear, as well as the length of the stop when you enter the 20 to 10ft range. If you choose not to do the mandatory safety stop, which I strongly advise that you do the stop, you'll be penalized on subsequent dives.

A decompression stop would be indicated if you exceeded the NDL. You'll see the Ceiling symbol appear, arrows, ASC TIME symbol, and the amount of time required to reach the surface including stops. The tell tell sign of a decompression stop is the ASC Time symbol. If it appears then the dive has became a deco dive and you MUST do the stop. If you skip the stop, you'll see the Er symbol appear. You have 3 minutes to go back down and do the stop or else the Cobra will lock you out for 48hrs. It will still operate in Gauge mode, but no NDL info will be displayed.

 

[Diverl]

Jana

I think warhammer has given you the information you need, however I have a question for you. When you ask if the computer will lock you out if you skip a deco stop are you refering to the computers suggested safety stop or are you actually talking about exceeding your NDL?

unfortunitly accidents happen and people exceed thier NDL's. The computer should be able to suggest a plan to get out of the situation. If you ignore its advice it will lock you out. If you follow its advice you should not get locked out.

If you do ignore its advice you better have a good reason!

If you are intentionally exceeding your NDL's I would suggest a different computer and the proper training.

 

[bradymsu]

Warhammer offer an excellent explanation of the Cobra. One of the nicest things about it is that you can still use it in guage mode if you do violate the rules. Of course it would be hard to break the limits of even a conservative computer like the Cobra during recreation diving and on one tank of air if you are monitoring your computer at all. The Cobra has a big display that shows how much time you have left to the no deco limit. Its audible alarms are hard to hear though if you are wearing a hood. And yes, the Cobra can function as a deco computer, though if you intend to do tech diving (all deco diving is tech) you should only use your computer to complement tables. Dive planning is absolutely mandatory with tech diving.

If you get the Cobra, I would suggest also buying a clip to attach it to your chest with the hose running under your arm. This keeps the computer safely out of harms reach and from dragging along the bottom. I don't like putting things on my wrist either. As I do a lot of wreck diving, I use my arms alot to move along and through wrecks. That means there's a greater chance of bumping a wrist mounted computer than one up against my chest.