Gas Pressure Indication Redundancy

[ianr33]

Your SPG is a backup for your brain. You should know what your tank pressure is at by looking at your depth and bottom time. Plain and simple.

Did a dive once where my buddy had his spg tangled up so he could not read it. He never bothered looking at it during the dive.
Profile was 200 for 20 minutes. Double 80s and deco tanks.
Still not sure if that was stupid or skilled.

 

[fnfalman]

When a simpler system such as an analog spg has a much lower incidence of failure
and probably less of a need to back up why would you want to add electronics to that
important bit of information. In ten years I have had approximately three electronic
items shut down at depth. Incidence of analog spg failure in same ten years...ZERO.
Slight inaccuracys maybe on the analog spg but failure to give me my PSI has never
happened.

When an even simpler system like the J-valve is available, why bother putting on more failure points in the form of the SPG and its hose?

 

[JamesK]

comparing is SPG to a j valve is ridiculous,

 

[fnfalman]

comparing is SPG to a j valve is ridiculous,

Why?

The J valve had worked for decades. If you're well trained and use that organic computer between your ears, then what's the problem? Why need some more things attached to your rig that would induce more failure points?

 

[jar546]

You folks can argue all you want with each other but I see this as quite simple.

In basic, simple, recreational diving where you are on a dive boat and one of the main rules is that you have the ability to monitor your gas pressure, those with electronics for monitoring should have an spy as a backup so that they don't lose a day of diving OR cause the rest of the group to have to return to the boat because the weakest link who lost their ability to monitor their gas. We are not talking about preplanned cave or technical dives or solo or private dives where you are very familiar with your gas consumption and or planning. Real simple. Dive operators have rules and I would not want to lose a trip simply because I did not have a basic functioning way to monitor my gas. You can dive without a computer, you can dive without a depth gauge if you know where you are diving or have a buddy that can show you depth. You cannot dive in recreational situations, especially with dive operators who have rules and liability without a way to monitor your gas.

J-Valve? Really? I guess thats why they still manufacture them and sell them today, right? I know the concept and understand it and dove them but really? More points to be a potential failure point I can see but not for an SPG. Gas monitoring is one of the number one items that needs to be accomplished on any dive.

If you don't want to have redundancy, no problem. Just don't let it affect my dive. That is exactly what happened to me because of someone else's electronic failure on a directly connected computer.

This of course is my opinion and we are all entitled to our opinions, they are not right or wrong; they are opinions.

I love my transmitter on my Luna, really love it. I have an SPG. I had a transmitter failure once on dive 2 of a long boat ride and did not care as I had an SPG attached. I just simply dove as if there was nothing wrong.

 

[t-mac]

You folks can argue all you want with each other but I see this as quite simple.

In basic, simple, recreational diving where you are on a dive boat and one of the main rules is that you have the ability to monitor your gas pressure, those with electronics for monitoring should have an spy as a backup so that they don't lose a day of diving OR cause the rest of the group to have to return to the boat because the weakest link who lost their ability to monitor their gas. We are not talking about preplanned cave or technical dives or solo or private dives where you are very familiar with your gas consumption and or planning. Real simple. Dive operators have rules and I would not want to lose a trip simply because I did not have a basic functioning way to monitor my gas. You can dive without a computer, you can dive without a depth gauge if you know where you are diving or have a buddy that can show you depth. You cannot dive in recreational situations, especially with dive operators who have rules and liability without a way to monitor your gas.

J-Valve? Really? I guess thats why they still manufacture them and sell them today, right? I know the concept and understand it and dove them but really? More points to be a potential failure point I can see but not for an SPG. Gas monitoring is one of the number one items that needs to be accomplished on any dive.

If you don't want to have redundancy, no problem. Just don't let it affect my dive. That is exactly what happened to me because of someone else's electronic failure on a directly connected computer.

This of course is my opinion and we are all entitled to our opinions, they are not right or wrong; they are opinions.

I love my transmitter on my Luna, really love it. I have an SPG. I had a transmitter failure once on dive 2 of a long boat ride and did not care as I had an SPG attached. I just simply dove as if there was nothing wrong.

With you completely! Never had a problem personally, but anything I can do to easily reduce even a small probability of ending or reducing my limited dive time I will do. And I'm not giving up my wireless AI computer. I may not need it, but I like it. As I often say about the cars I drive, "this is not about need, it is about want" and sometimes that's just life. It works in my world.

 

[ScubaSteve]

Once again "electronics" caused a problem. At the very least, if you use electronics for gas pressure, you should have an analog spg as a backup.

Through a dive I always have a good idea of where I am in the process of draining my tank. I have had issues which caused me to no longer trust the digital display of my Suunto Cobra AI computer. I had been checking my air/depth/NDL etc enough through the dive to know that I could safely ascend and do an extended safety stop dive to my exit point with the air I knew I had remaining. I had my buddy there with me just in case something happened. I do not see why you are telling people that they must dress themselves up to look like an octopus when all it takes is awareness and some thought to be prepared. I carry a wrist mounted N2ition which, should my Cobra ever pooch on me during a dive, would serve to get me to the surface at a safe rate of speed and still track my time. It is not there for air because I have both a buddy and a pony should the need ever present itself.

 

[doctormike]

With you completely! Never had a problem personally, but anything I can do to easily reduce even a small probability of ending or reducing my limited dive time I will do. And I'm not giving up my wireless AI computer. I may not need it, but I like it. As I often say about the cars I drive, "this is not about need, it is about want" and sometimes that's just life. It works in my world.

You know, the reason that we have this board and these discussions at all is not so that we can promote our own versions of what works, but to listen to each other, and occasionally learn from people with different and/or greater experience than our own.

I don't think that anyone was seriously suggesting that we all go back to J valves instead of SPGs. I don't want to put words in someone else's mouth (and correct me if I'm wrong) but I read that as a mildly sarcastic response to the argument that analog SPGs are always better than electronic ones because they are simpler.

As far as the commonly held position - "I will do anything that will give me even a tiny percentage advantage in X situation", you might want to listen to what some people with a lot of experience are saying here. Because by that logic, there really is no end to the clutter that you can end up bringing with you. And one of the best things that I have done in my training is to reduce my clutter and streamline my rig without losing any mission-critical equipment.

So... two cutting tools? Yes. Backup lights in a cave? Yes. Nautilus GPS on an ocean dive in current? Yes. Each of those things can save your life.

Redundant gas monitoring just to let you keep diving in the very unlikely (and non-lethal) situation where your analog or digital SPG quits? Well, I guess that's a tradeoff of the associated the cost and clutter, and you can make that calculation yourself. But I wouldn't be so quick to dismiss the other point of view as simply a matter of personal preference without some good logic behind it.

 

[fnfalman]

You folks can argue all you want with each other but I see this as quite simple.

In basic, simple, recreational diving where you are on a dive boat and one of the main rules is that you have the ability to monitor your gas pressure, those with electronics for monitoring should have an spy as a backup so that they don't lose a day of diving OR cause the rest of the group to have to return to the boat because the weakest link who lost their ability to monitor their gas.

Okay, so we're diving in a group and my fancy dandy computer gave up. What does that have to do with you? Why do you have to terminate your dive? I'd have to terminate my dive (if I were smart, that is). And then I may lose a dive or two, but then why does that concern you? You're not the one losing dives.

We are not talking about preplanned cave or technical dives or solo or private dives where you are very familiar with your gas consumption and or planning.

What? Us poor rec divers are too dumb to know how to calculate for our air consumption rate?

Real simple. Dive operators have rules and I would not want to lose a trip simply because I did not have a basic functioning way to monitor my gas. You can dive without a computer, you can dive without a depth gauge if you know where you are diving or have a buddy that can show you depth. You cannot dive in recreational situations, especially with dive operators who have rules and liability without a way to monitor your gas.

Then YOU choose a dive operator that doesn't have these nanny rules. There are many dive operators and they all have different policies.

J-Valve? Really? I guess thats why they still manufacture them and sell them today, right? I know the concept and understand it and dove them but really? More points to be a potential failure point I can see but not for an SPG. Gas monitoring is one of the number one items that needs to be accomplished on any dive.

SPG? Really? Don't you know that they have air integrated computers now with piezoelectric transducers that don't have nearly as large of an error as an SPG? Don't you know that SPG could be off by 300-PSI?

If you don't want to have redundancy, no problem. Just don't let it affect my dive. That is exactly what happened to me because of someone else's electronic failure on a directly connected computer.

Sure, no problem. Don't dive with me and I don't dive with you.

This of course is my opinion and we are all entitled to our opinions, they are not right or wrong; they are opinions.

Same with me. You dive your way and I dive my way. If the twain never shall met, then oh well, it's a big planet.

I love my transmitter on my Luna, really love it. I have an SPG. I had a transmitter failure once on dive 2 of a long boat ride and did not care as I had an SPG attached. I just simply dove as if there was nothing wrong.[/QUOTE]

 

[Splitlip]

Some of these posts really crack me up. Like an spg hose or transmitter is clutter.

My first dives were made with j-valves and first and second stage reg. Had a plastic backpack, watch on left wrist and capillary depth gauge on the right. The first piece of modern gear I purchased was a Scubapro Sea View Gauge (today they are genericall referred to as spg's). I had it before a bc and before an octo.
Today, as then, I dive with three gauges. Only difference is my watch is also a computer. My depth gauge is now an AI wireless wrist computer. Still diving the spg the same way. Clutter? Bull. Oh wait, I added a transmitter about the size of pack of gum to the first stage behind my head. Oh well, there goes my streamlining. Give me a break.

And then there is this crap about losing an spg not being an issue if you've done proper gas planning. Any number of things can change the plan in my experience. (before you challenge me: Nice leisurely drift with my daughter when I got hooked with some monofilament. I had to wrestle and she had to fin up current to stay/get with me. My buddy, Scott the cave diver, got ratcheted into a restriction and worked really hard to extricate himself. Of course, while hunting there is little to the plan beyond turning the dive at "X". Would you guys really continue to dive with an spg failure?)

Here's an idea. Let's all just lose our spg's. Too much clutter after all. They're not needed in any case so long as we have done proper planning and rely on our training and brains.