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Article: Air integrated dive computers
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Dr. Lecter
Contributor
When your computer stops functioning as expected, why do you assume you've only lost the AI transmitter signal? Let's say I agree that being unable to check your gas level is NBD...why are you so sure your computer isn't suffering some other failure that's also affecting the AI?
AI is an expensive, bulky, less than reliable solution in search of a problem. It's not going to kill you and data junkies should love the fact it means they don't have to do any thinking in order to determine gas consumption, but it's not much different from being a dangling Christmas tree of junk.
You're also saying two things about about the nature of HP hose failures: first that they quickly drain your gas (false), then that they take forever to drain a tank due to the pinhole restriction in the 1st stage's HP port (true). It's confusing, at best. But since you claim not be engaing in conjecture (hint to other readers: you are), let's hear your evidence for how an HP hose is more likely to fail than an o-ring.
Which is not to say that you're wrong about the transmitter vs. hose/gauge reliability debate. The transmitter has a single static o-ring (I'm assuming it's impossible for the pressure sensor to blow out...it's not, but it's so unlikely as to be irrelevant)...that's it. The SPG has that same o-ring plus a pair of tiny dynamic o-rings on an air spool plus perhaps another one in the hose. Technically, that's a few more failure points. Realistically, you're fairly likely to get some champagne bubbles at your SPG swivel connection sooner or later.
But the debate is pretty much moot because neither one suffers catastrophic failures ever. Seriously...aside from the early miflex hoses, the SPGs and hoses almost never break, burst, get cut, or extrude an o-ring. They bubble a bit, and you can still use them. AI, on the other hand, is either working or not working...and while the not working state is usually an easy fix, it still means you're aborting the dive. Not good.
We'll overlook that HP hose failures are a lot less common than transmitter link interruptions. You're clearly cool with ending your dives at the drop of a hat (or you're saying what you think everyone should hear you say, and would actually keep diving without the AI link...which is probably the most common approach).
AI is an expensive, bulky, less than reliable solution in search of a problem. It's not going to kill you and data junkies should love the fact it means they don't have to do any thinking in order to determine gas consumption, but it's not much different from being a dangling Christmas tree of junk.
You're also saying two things about about the nature of HP hose failures: first that they quickly drain your gas (false), then that they take forever to drain a tank due to the pinhole restriction in the 1st stage's HP port (true). It's confusing, at best. But since you claim not be engaing in conjecture (hint to other readers: you are), let's hear your evidence for how an HP hose is more likely to fail than an o-ring.
Which is not to say that you're wrong about the transmitter vs. hose/gauge reliability debate. The transmitter has a single static o-ring (I'm assuming it's impossible for the pressure sensor to blow out...it's not, but it's so unlikely as to be irrelevant)...that's it. The SPG has that same o-ring plus a pair of tiny dynamic o-rings on an air spool plus perhaps another one in the hose. Technically, that's a few more failure points. Realistically, you're fairly likely to get some champagne bubbles at your SPG swivel connection sooner or later.
But the debate is pretty much moot because neither one suffers catastrophic failures ever. Seriously...aside from the early miflex hoses, the SPGs and hoses almost never break, burst, get cut, or extrude an o-ring. They bubble a bit, and you can still use them. AI, on the other hand, is either working or not working...and while the not working state is usually an easy fix, it still means you're aborting the dive. Not good.
We'll overlook that HP hose failures are a lot less common than transmitter link interruptions. You're clearly cool with ending your dives at the drop of a hat (or you're saying what you think everyone should hear you say, and would actually keep diving without the AI link...which is probably the most common approach).
I'm not quite clear what your complaint is. . . given that the diver is monitoring their air supply in a manner that makes AI an assist, not a necessity, what is your complaint?
So AI fails, I still have an SPG (in fact I dive with a 2 gauge console in case my primary and backup computer fails). No big deal. Certainly you're not going to try the Jablonski "computers are evil" line, are you?
Dr. Lecter
Contributor
The OP was contrasting reliability of AI vs. SPG - neither I nor the OP are addressing the situation where you've decided to have both systems running at once (though I'll refer you to my Christmas tree diver point as to my thoughts on that).
I don't have a complaint, aside from the OP's specious claims about AI's potentially superior reliability. If you want to dive a triple bladder wing, use a made in china pistol-grip dive light, and/or stick a transmitter worth more than your 1st stage on every reg you own...I really could not care less. If you just like seeing gas pressure on your wrist, and/or you want that data logged...whatever floats your boat.
Just don't try and pretend it's more reliable than an SPG, as the OP just did, and I'll be happy to send you your way while I go mine.
I don't have a complaint, aside from the OP's specious claims about AI's potentially superior reliability. If you want to dive a triple bladder wing, use a made in china pistol-grip dive light, and/or stick a transmitter worth more than your 1st stage on every reg you own...I really could not care less. If you just like seeing gas pressure on your wrist, and/or you want that data logged...whatever floats your boat.
Just don't try and pretend it's more reliable than an SPG, as the OP just did, and I'll be happy to send you your way while I go mine.
OP
Thanks for reading and commenting. I would tend to agree with you Dr. Lector in that failures in either system are very, very rare. As such I’m willing to contend the discussion isn’t a terribly important one in diver safety - but I like talking gear. =)
The early, thin miflex hoses aside - I have only witnessed maybe half a dozen burst hi-pressure hoses, and that’s in a very large number of dives - more often than not with students, so the number - to be fair - should be multiplied by however many. Thus in my own anecdotal, personal, experience hi-pressure hoses only fail catastrophically in probably-I-don’t-know significantly less than one in a thousand dives. (And I can actually only recall seeing it twice under water - because, as you know, the burst usually happens when you pressurise the hose when setting up.)
Incidentally, the thin miflex hoses are still for sale in this part of Europe (all of Europe?) - and they’re still …. temperamental, in my experience. I just don’t want to dive with them.
JohnN, I’m also curious why you would want to dive with both a transmitter and an SPG? I don’t see any real benefits, just - well, extra clutter? If you’re worried about catastrophic air-loss, you’re only increasing the likelihood of that, by introducing more failure points. By adding a SPG to a transmitter, you’re getting rid of some of the benefits that transmitters actually convey (less clutter, more streamlining, less entanglement points (depending a lot on how you orient the transmitter on the first stage, but that another discussion.) If you don’t trust the transmitter - why dive with it? =)
Dr. Lector, you ask for my evidence of how a HP hose is more likely to fail than an o-ring. Looking at my submission, I don’t think I claimed that. (Nor would I ever be able to prove it, just as - the contrary can't be proven either I suppose?) - what I meant to imply was that an o-ring is less likely to fail than an o-ring AND a hose. That’s all.
I disagree with your whole paragraph about "dangling christmas trees of junk." I don’t think transmitters are the answer to a problem that doesn’t exist. They’re an alternate, but totally valid, safe and reasonable air monitoring system. Are they more prolific on the sort of diver who'll use split-and-gear-shift fins, use Mares HUBS or dive with tripple-purge-valve, dry snorkels? I don’t know, but I could well speculate that’d be the case, and I think that’s what you imply as well. That doesn’t mean transmitters aren’t good or safe, just that people who like gadgets, will buy gadgets. Some of those gadgets will be crap, but transmitters aren't.
You point about the loss of signal as a symptom of another possible failure in the computer is valid. I contend that a general computer failure would also jeopardise your gas-information.
Lastly - for the record, I dive with both transmitters ad SPG’s (though never at the same time.) I dive much more with transmitters than not, but when I’m with the DIR crowd I’m using SPGs (when in Rome, right) I’m completely confident with either system, but I also carry stages and/or have a manifold for when that hose burst =)
Do I still think transmitters are more safe with regards to prevention of air-loss (not any other malfunctions.) than SPGs? Yes, I do. Do I think it a marginal risk, in either case? Yes.
edit: spelling
The early, thin miflex hoses aside - I have only witnessed maybe half a dozen burst hi-pressure hoses, and that’s in a very large number of dives - more often than not with students, so the number - to be fair - should be multiplied by however many. Thus in my own anecdotal, personal, experience hi-pressure hoses only fail catastrophically in probably-I-don’t-know significantly less than one in a thousand dives. (And I can actually only recall seeing it twice under water - because, as you know, the burst usually happens when you pressurise the hose when setting up.)
Incidentally, the thin miflex hoses are still for sale in this part of Europe (all of Europe?) - and they’re still …. temperamental, in my experience. I just don’t want to dive with them.
JohnN, I’m also curious why you would want to dive with both a transmitter and an SPG? I don’t see any real benefits, just - well, extra clutter? If you’re worried about catastrophic air-loss, you’re only increasing the likelihood of that, by introducing more failure points. By adding a SPG to a transmitter, you’re getting rid of some of the benefits that transmitters actually convey (less clutter, more streamlining, less entanglement points (depending a lot on how you orient the transmitter on the first stage, but that another discussion.) If you don’t trust the transmitter - why dive with it? =)
Dr. Lector, you ask for my evidence of how a HP hose is more likely to fail than an o-ring. Looking at my submission, I don’t think I claimed that. (Nor would I ever be able to prove it, just as - the contrary can't be proven either I suppose?) - what I meant to imply was that an o-ring is less likely to fail than an o-ring AND a hose. That’s all.
I disagree with your whole paragraph about "dangling christmas trees of junk." I don’t think transmitters are the answer to a problem that doesn’t exist. They’re an alternate, but totally valid, safe and reasonable air monitoring system. Are they more prolific on the sort of diver who'll use split-and-gear-shift fins, use Mares HUBS or dive with tripple-purge-valve, dry snorkels? I don’t know, but I could well speculate that’d be the case, and I think that’s what you imply as well. That doesn’t mean transmitters aren’t good or safe, just that people who like gadgets, will buy gadgets. Some of those gadgets will be crap, but transmitters aren't.
You point about the loss of signal as a symptom of another possible failure in the computer is valid. I contend that a general computer failure would also jeopardise your gas-information.
Lastly - for the record, I dive with both transmitters ad SPG’s (though never at the same time.) I dive much more with transmitters than not, but when I’m with the DIR crowd I’m using SPGs (when in Rome, right) I’m completely confident with either system, but I also carry stages and/or have a manifold for when that hose burst =)
Do I still think transmitters are more safe with regards to prevention of air-loss (not any other malfunctions.) than SPGs? Yes, I do. Do I think it a marginal risk, in either case? Yes.
edit: spelling
My observations based on use:
1. My AI is not as accurate as my SPG. Oceanic, at least on my unit shows a average 150 psi lower that my SPG. This is not a issue when recreationally diving, but it is a alarm tone annoyance when under 1000 psi.
2. ATR is no where near accurate enough for anything past a recreational diving reference point. My guess is that the programming is lawyered up as to keep Oceanic out of lawsuits.
3. On my unit, the AI looses connection for 15ish seconds (you can see this on the raw data log) one out of every 5 or so dives. This loss data is irrespective of the algorythm calculations as the dive computer functions are based on the unit's readings and not the transmitter's. There is no issues with log calculations as it extrapolates the data.
4. My AI transmitter has taken a beating and I don't question Oceanics build quality.
5. The logged data and transmitting that data to MacDive is fast and seemless. This is the main reason I use it.
6. The SAC rate calculation is accurate (although pressure reading is 150 psi lower, the start and end pressures reflect this so the gas used is accurate)
AI is a nice recreational feature for lazy mans dive logging. Definitely not accurate enough, for me, to confidently replace a SPG.
1. My AI is not as accurate as my SPG. Oceanic, at least on my unit shows a average 150 psi lower that my SPG. This is not a issue when recreationally diving, but it is a alarm tone annoyance when under 1000 psi.
2. ATR is no where near accurate enough for anything past a recreational diving reference point. My guess is that the programming is lawyered up as to keep Oceanic out of lawsuits.
3. On my unit, the AI looses connection for 15ish seconds (you can see this on the raw data log) one out of every 5 or so dives. This loss data is irrespective of the algorythm calculations as the dive computer functions are based on the unit's readings and not the transmitter's. There is no issues with log calculations as it extrapolates the data.
4. My AI transmitter has taken a beating and I don't question Oceanics build quality.
5. The logged data and transmitting that data to MacDive is fast and seemless. This is the main reason I use it.
6. The SAC rate calculation is accurate (although pressure reading is 150 psi lower, the start and end pressures reflect this so the gas used is accurate)
AI is a nice recreational feature for lazy mans dive logging. Definitely not accurate enough, for me, to confidently replace a SPG.
Simple (at least to me). . . my SPG on the left hip "D" ring doesn't add any clutter, and I like having redundancy. If my AI transmitter fails or burps (and it has), I can continue my dive.
Why AI in the first place? I like the convenience of having my pressure on my wrist. Besides I got my computer + transmitter for a killer price and I like having it compute my SAC.
AfterDark
Contributor
I don't use one and never expect to in the future. Maybe if the price went way down or I won one in a contest.
IMO this type of technology has come a long way but, no enough to gain my trust.
That a side for what it gives a diver it is IMO way overpriced. I know with a glance at a couple of instruments that I trust and have stood the test of time how much gas I have and how long it will last. Why do I need some device costing hundreds of dollars to tell me what I can already find out with gear I have?
I can imagine people that only dive on vacations might find this gizmo useful, but I can't imagine anybody that dives regularly requiring it.
IMO this type of technology has come a long way but, no enough to gain my trust.
That a side for what it gives a diver it is IMO way overpriced. I know with a glance at a couple of instruments that I trust and have stood the test of time how much gas I have and how long it will last. Why do I need some device costing hundreds of dollars to tell me what I can already find out with gear I have?
I can imagine people that only dive on vacations might find this gizmo useful, but I can't imagine anybody that dives regularly requiring it.
CamC
Contributor
As a predominantly vacation diver and a bit of a sad gadget freak I upgraded from a Vyper to a D4i AI for my last trip to Egypt (my daughter is now the happy owner of the castoff Vyper) and I found it very useful indeed. This is hardly a statistically significant sample I know (before the good Doctor jumps down my throat
) but it worked really well for an occasional amateur like myself.As it was my first time out with AI I kept the SPG for redundancy, but I probably only looked at it 3 or 4 times the entire trip. It stayed tucked away unobtrusively when not in use, and I see no real reason to disconnect it going forward.
Having depth, time and air all on the wrist at a glance shouldn't save much actual energy, but I was definitely more relaxed psychologically and I could see a slight but definite improvement in my air consumption. Whatever the cause - or effect - the AI works really well for me. YMMV.
I use AI with no back up and love it. Many, many dives with no failures. I do however keep a spg on the boat/shore in my dive bag just in case but have never needed it. The pluses I have found that in downloading the computer it tracks my air usage better and less hoses and bulk.
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