Use a backup SPG with air integration?

[stuartv]

If you lose signal during a dive (which happens all the time)

What brand(s) and model(s) of computer and AI transmitter have you had this experience with?

 

[Dan]

I agree with this. A backup mini Spg on a thin hose takes almost no space, it weighs next to nothing, it rolls up tight for storage and travel, it's easily tucked behind your BCD, it makes it really easy to get an immediate tank pressure reading during the pre-dive check when your AI computer might not be reading the tank because you weren't close enough to it, and you've got the piece of mind of knowing you won't have to end a dive or guess at your air pressure for part of a dive if you have a failure of either the transmitter or receiver. If you lose signal during a dive (which happens all the time) you don't need to worry because if there is a problem you know you've got that mini spg tucked away, so it's peace of mind. It's like the spare tire in the trunk of your car. You almost don't even know it's there until you need it.

Great minds think alike
I did the same 4 years ago.
See my post #6 Use a backup SPG with air integration?

 

[rek_diver]

What brand(s) and model(s) of computer and AI transmitter have you had this experience with?

Oceanic VT Pro with matching transmitter. It happens occasionally during a dive ( know I said in my earlier post it happens "all the time" I should have said, it happens often enough, or used different wording.. whatever.. and it's a known "issue" if you want to even call it that. The numbers flash to tell you that the computer is providing you with the last known data. It doesn't lose the signal for more than, say a half a minute or so especially if it's because you've got your arm in a position that brings it out of optimum range for the transmitter and then you move it back.

 

[stuartv]

Oceanic VT Pro with matching transmitter. It happens occasionally during a dive ( know I said in my earlier post it happens "all the time" I should have said, it happens often enough, or used different wording.. whatever.. and it's a known "issue" if you want to even call it that. The numbers flash to tell you that the computer is providing you with the last known data. It doesn't lose the signal for more than, say a half a minute or so especially if it's because you've got your arm in a position that brings it out of optimum range for the transmitter and then you move it back.

Which arm do you wear your computer on? And what side of the 1st stage do you have the transmitter on? I assume the transmitter is pointing straight out to the side?

I have an Oceanic computer with AI. And a Perdix AI and had a Hollis TX-1. They all work with the same transmitter.

As long as my computer is on the same side arm as the side that the transmitter is on, I never have any problems. If I put my computer on my left arm and my transmitter is pointing out to the right side of the 1st stage (or vice versa), then I will occasionally have a dropout, but it always reconnects and updates the displayed pressure within 1 to 2 seconds of holding the computer up in front of my face. Normally, my computer and the transmitter are both on the right side and I have no dropouts at all.

Are you saying that what you have experienced is a "known issue" specifically of the VT Pro computer? I don't really know anything about that specific computer.

 

[rek_diver]

The transmitter is on the right side of my first stage, and I wear the wrist computer on the right arm.

Yes, in the VT Pro user manual it states that the receiver may lose the signal from time to time, in which case the digits will flash indicating that the signal is momentarily lost, and gives a few suggestions on how to re-aquire the signal including changing arm position, and possibly reconfiguring the regulator if the problem is severe. It's never been a big issue, the signal is never gone for more than a minute.

 

[dmaziuk]

it makes it really easy to get an immediate tank pressure reading during the pre-dive check

And this is why I think a LED in the transmitter is such a great idea.

 

[rmssetc]

Let's break this down a bit.

If your AI goes out, you end the dive and come to the surface

What "goes out"? Was it just the "Air Integration" or was it the computer, including the dive log and N2 loading?

what do you do on the NEXT dive? With an SPG and hose (and wrench) in your kit, you can keep diving.

Sure, you can keep diving if you have a spare SPG and can measure depth, bottom time, and can reasonably estimate N2 loading, including the dive where the AI failed and previous dives. So, if the failure wasn't in the computer, but just the SPG function, you're OK with a spare SPG. If the computer failed, then it gets much more complicated. Do you have enough info to guesstimate tables for the previous dive and each one w/in 24hrs? Do you have a spare bottom timer & depth gauge? Do you have tables?

I'm making the wild guess that almost any failure of an AI system (wireless or a hosed console) that's sufficient to make the tank pressure unavailable will also make the computer (depth gauge, timer, track of accumulated N2) unavailable.

For me, dive trips are too rare for me to easily say that I'll skip the next 24hrs of diving in the event of a computer failure. My personal solution was to replace my SPG with an old AI console. Fairly cheap, easy backup for not just the pressure reading but for accumulated dive logging during a trip.

Is there enough data here on SB to make a realistic estimate of failure rates for the following during a dive?

Hosed AI

1. hose/swivel o-ring
2. SPG function of computer (ie., depth gauge, timer, log are functional)
3. transient computer failure due to battery (depth gauge, timer, SPG unavailable during dive, but are functional after battery replacement during next SI)
4. long-term computer failure (depth gauge, timer, SPG unavailable until computer is repaired/replaced)

Wireless AI

1. transmitter o-ring (or hose if it's on a short hose)
   
2. SPG function of computer (ie., depth gauge, timer, log are functional but it does not receive a signal from the transmitter)
3. transient failure due to transmitter battery (depth gauge and timer are available during dive, SPG is functional after battery replacement during next SI)
4. transient failure due to computer battery (SPG, depth gauge and timer are unavailable during dive, all functions restored after battery replacement during next SI)
   
5. complete long-term failure (depth gauge, timer, SPG unavailable until computer&transmitter combo are repaired/replaced)
6. loss of computer (fell off wrist, band breaks, etc)

For me, the transient failures above due to to batteries are the least likely -- it's easy to check & change batteries before getting wet. Of the other failure modes, only "Wireless AI #2 (lack of signal from transmitter)" seems likely to happen and leave me with a functional depth gauge/timer and N2 history.

 

[scubadada]

Which arm do you wear your computer on? And what side of the 1st stage do you have the transmitter on? I assume the transmitter is pointing straight out to the side?

I have an Oceanic computer with AI. And a Perdix AI and had a Hollis TX-1. They all work with the same transmitter.

As long as my computer is on the same side arm as the side that the transmitter is on, I never have any problems. If I put my computer on my left arm and my transmitter is pointing out to the right side of the 1st stage (or vice versa), then I will occasionally have a dropout, but it always reconnects and updates the displayed pressure within 1 to 2 seconds of holding the computer up in front of my face. Normally, my computer and the transmitter are both on the right side and I have no dropouts at all.

Are you saying that what you have experienced is a "known issue" specifically of the VT Pro computer? I don't really know anything about that specific computer.

I wear my transmitter on the right side, I wear my computer on the left side. I rarely lose connection for more than 30 sec. I am generally unaware of these disconnections though they show up on downloads.

 

[tursiops]

Let's break this down a bit.

What "goes out"? Was it just the "Air Integration" or was it the computer, including the dive log and N2 loading?



Sure, you can keep diving if you have a spare SPG and can measure depth, bottom time, and can reasonably estimate N2 loading, including the dive where the AI failed and previous dives. So, if the failure wasn't in the computer, but just the SPG function, you're OK with a spare SPG. If the computer failed, then it gets much more complicated. Do you have enough info to guesstimate tables for the previous dive and each one w/in 24hrs? Do you have a spare bottom timer & depth gauge? Do you have tables?

I'm making the wild guess that almost any failure of an AI system (wireless or a hosed console) that's sufficient to make the tank pressure unavailable will also make the computer (depth gauge, timer, track of accumulated N2) unavailable.

For me, dive trips are too rare for me to easily say that I'll skip the next 24hrs of diving in the event of a computer failure. My personal solution was to replace my SPG with an old AI console. Fairly cheap, easy backup for not just the pressure reading but for accumulated dive logging during a trip.

Is there enough data here on SB to make a realistic estimate of failure rates for the following during a dive?

Hosed AI

1. hose/swivel o-ring
2. SPG function of computer (ie., depth gauge, timer, log are functional)
3. transient computer failure due to battery (depth gauge, timer, SPG unavailable during dive, but are functional after battery replacement during next SI)
4. long-term computer failure (depth gauge, timer, SPG unavailable until computer is repaired/replaced)

Wireless AI

1. transmitter o-ring (or hose if it's on a short hose)
   
2. SPG function of computer (ie., depth gauge, timer, log are functional but it does not receive a signal from the transmitter)
3. transient failure due to transmitter battery (depth gauge and timer are available during dive, SPG is functional after battery replacement during next SI)
4. transient failure due to computer battery (SPG, depth gauge and timer are unavailable during dive, all functions restored after battery replacement during next SI)
   
5. complete long-term failure (depth gauge, timer, SPG unavailable until computer&transmitter combo are repaired/replaced)
6. loss of computer (fell off wrist, band breaks, etc)

For me, the transient failures above due to to batteries are the least likely -- it's easy to check & change batteries before getting wet. Of the other failure modes, only "Wireless AI #2 (lack of signal from transmitter)" seems likely to happen and leave me with a functional depth gauge/timer and N2 history.

You finally answered your own question. Your whole post is unwarranted speculation. The issue is the transmitter stops. What then?.. YOU are bringing all kinds of additional failures. Lack of signal is THE big problem with AI, and mostly with Suunto, not the Oceanic/PPS transmitters. Yes, and batteries do run down. Either way, you no longer know your pressure. If you want to start another thread about all the other kinds of possible failures and their likelihood and what you do about it, go for it.

 

[rmssetc]

You finally answered your own question. Your whole post is unwarranted speculation. The issue is the transmitter stops. What then?.. YOU are bringing all kinds of additional failures.

This whole thread is unwarranted speculation. Oh, wait, this is Scubaboard...that was redundant of me.

Lack of signal is THE big problem with AI, and mostly with Suunto, not the Oceanic/PPS transmitters. Yes, and batteries do

Perhaps you should re-read the original post:

Thinking about the perdix AI. I get it that two is one and one is none when it comes to equipment failures, but what is the consensus for warm rec diving only?

Nothing about "lack of signal," nothing specific to the cause of the equipment failure. The "two is one and one is none" part implies to me a general understanding and interest in failure modes & consequences.

There's already been discussion in this thread about SPG spool o-ring failures, hose failures, people unscrewing transmitters, etc., so I don't understand why you choose to make a hostile response to my generalized answer in response to the original question of using a backup SPG while diving with an air-integrated computer.

run down. Either way, you no longer know your pressure. If you want to start another thread about all the other kinds of possible failures and their likelihood and what you do about it, go for it.

Um, a thread about possible failures of AI-integrated computers and the need for a backup SPG is exactly the open-ended question that the OP proposed. Lots of people took that in a much more specific direction (with good observations). Almost all the followups seemed to assume that the computer would be fine after the unspecified failure proposed by the original poster, and I wanted to offer the reminder that lack of pressure data on the computer might also have a root cause that affects other data, meaning that the SPG backup on it's own is not sufficient.