Dive computers... SO many choices!

[packrat12]

With Wireless AI, be prepared for connection issues. It is not a big deal in recreational diving but you might not get to dive or must leave it early if you do not have an alternate means of measuring gas supply. Lookup up connection issues for AI. It is far from a thing of the past. Also, you have a battery and a compartment that can flood. There are major failure points at this level of gear. From the many years of diving I have, Wireless AI is not more reliable then brass and glass SPGs. The most common failure point in SPGs is the airspool which comprises of a very small (insignificant) leak until repaired. I have had them leaking for years without incident nor being repaired. The hose failure is mitigated by maintenance and is easily replaced with a failure. In 1000+ dives, I have only had 1 hose failure on the HP side. This is also my only SPG failure total. All of the parts are inexpensive when compared to a Wireless transmitter alone and can easily be spared.

So far in 2016, I have seen :
1 Wireless AI drown (Water in circuit board) - last dive of the day so not a big deal but if it had been the first dive, they would have lost the second (might have even been a 3 tanker).
1 Wireless AI not sync up - almost cost the girl 2 dives, luckily the boat had a spare SPG and the tools to replace it.
1 button plastic SPG fail - Cheap and not what I call a brass and glass SPG - several of us had spare SPGs to replace that busted one while pretty much suited up to go.

Numerous times, nearly every recreational run, I see sync issues with a frantic connection. They are resolved most of the time.
This is why I find it incorrect to call it more reliable then SPGs! I still have mine from 30 years ago, fully functional and working. I also can cheaply and easily carry a spare, which I do.

Overall, for recreational diving, I like AI. I just believe that if the dive is critical to you, an alternative (SPG) should be considered. I like the data that it can present and that can be retrieved from it. It is a personal choice and should not be depended upon. I know when I do periodic buddy checks, I do not bother with the AI but rather look directly at the PSI.

 

[Diving Dubai]

With Wireless AI, be prepared for connection issues. It is not a big deal in recreational diving but you might not get to dive or must leave it early if you do not have an alternate means of measuring gas supply. Lookup up connection issues for AI. It is far from a thing of the past.

I understand the point you are trying to make. I for one still keep SPG's on my tanks, I use them for setting up, for the buddy check and for the double check before I splash. I don't buy into the streamlining argument by others - it's not as if hoses and SPGs create massive drag vortices

The more modern AI systems are "Paired for life" meaning once paired they say paired, so a lot of the connection issues of old are mute.

I don't buy into the extra failure points of a transmitter, nothings perfect of course, but I've seen more leaks from LP hoses, regs, tanks etc than from TX failures. A lot of course depends on how you look after your kit

 

[dmaziuk]

Exactly what type of *wrist* computer is appropriate for an advanced diver?

The best computer is the one you know how to use.

 

[stuartv]

++1 to what @stuartv said above, except for the bit about the Suunto computers

All I said was that I have seen a lot of Zoops (and Giottos) for sale because the owner decided it was too conservative. I have never seen an Oceanic or Sherwood computer for sale because the owner felt it was too conservative....

Agree. Good to have young eyes!

I'm 50 and wear reading glasses! I was able to read the numbers on my Atom without help, but couldn't read the labels for the numbers. That's not a big deal, since even if you don't "know" the computer, what numbers are what is pretty obvious. However, my computer isn't the only thing I wanted to be able to see clearly up close during a dive, so I got Hydro-Tac stick-on reader lenses for my mask, which worked perfectly and never came off. But, then I bought new masks that seal to my face better and I got them with gauge reader lenses built-in because it didn't cost me anything. Now, I can read the Atom display including the small labels next to the big numbers... and see small critters up close, too!

That's actually not true. The Petrel 2 lets you customize what's in the center row, and one of the options for one of the three data spaces is a little compass, which is easy to use. So you don't need to have it switched into "compass mode" just to use the compass, you can have the heading there and still have lots of other data.

Actually, in your example, it is exactly true. You have to give up some other piece of data in order to have that compass displayed - which is just what I said.

I completely agree. Every livaboard or commercial dive centre I've been too has Suuntos.

@stuartv and I disagree about liberal conservatism, (And I think we've reached a point where we agree to disagree)

All I said (in this thread) was that I have seen a lot of Zoops for sale for being too conservative. I didn't knock Suuntos in general. And I'm not actually sure we disagree at all. I don't knock all Suuntos for being too conservative, but there are SOME (probably even many) Suuntos that I would say are too conservative for my tastes. I do acknowledge that you can set some, like the Eon Steel, to be equally liberal as any other computer.

Exactly. I think that a lot of people who buy computers because they have liberal algorithms actually think that they are somehow affecting their decompression stress with a magic bracelet!

Maybe so, but that seems like a pretty sweeping denigration of a whole lot of divers. I have no evidence to support this, of course, but I FEEL like most divers who bother to inquire regarding the algorithm of a computer before they buy it have at least some idea that the computer doesn't change how much nitrogen their body absorbs and that what it does it let them have (potentially) longer bottom times while still staying within limits that at least that computer's manufacturer believes are safe.

For as many divers as may think a magic bracelet is going to wipe away their risk of DCS, I think there are just many "experienced" divers who think any computer that is more liberal than whatever they are used to is just too dangerous - even though they've never been bent and have no actual data to support the notion that their computer is "just the right amount" of conservative. If you've (not meaning you, personally, doctormike) never been bent, then how do you know what you are doing is Safe versus "Seriously Overconservative"?

With Wireless AI, be prepared for connection issues. It is not a big deal in recreational diving but you might not get to dive or must leave it early if you do not have an alternate means of measuring gas supply. Lookup up connection issues for AI. It is far from a thing of the past. Also, you have a battery and a compartment that can flood. There are major failure points at this level of gear. From the many years of diving I have, Wireless AI is not more reliable then brass and glass SPGs. The most common failure point in SPGs is the airspool which comprises of a very small (insignificant) leak until repaired.

In almost 2 years, I have never had a problem or connection issue with my AI. OTOH, I got a brand new BnG SPG, which came assembled, last summer. In less than 10 dives, it blew an O-ring on the spool. Why? Because the SPG itself had come loose and gradually unscrewed itself from the HP hose. It was still on there by its last couple of threads, but it was loose enough to pop the O-ring. Fortunately, it happened right after I assembled my rig and turned on the gas, versus happening in the water (and potentially having the SPG finish coming loose and fall off and be lost).

Whether it's an SPG or AI, if it is maintained correctly, it should be reliable.

Whether it's an SPG or AI, if it fails during a dive, it's pretty unlikely to be life-threatening. Though it seems to me that the more common failure modes would make a failed SPG the more likely item to have a failure be life-threatening.

If an AI connection blanks out for a minute, why is that a big deal. Wait a few seconds or a minute and check it again.

If the AI transmitter totally dies, it's no worse than an SPG dying. You may need to end the dive early. Or, if you have planned your dive at all, which implies having a good idea of your SAC among other things, you can probably finish your dive, maybe a little conservatively, even with a failed AI transmitter. I know pretty much all my NC wreck dives, I'm going to run out of NDL WAY before I get low on air. So, if I only had AI and it failed, I would almost certainly continue on and finish my dive anyway. Just as I would if something happened and, say, my SPG needle was stuck on 3500 psi for the whole dive.

If you wouldn't use AI because it has a battery compartment that could flood, then I would ask, do you use a computer? Does it have a battery compartment that could flood? I don't know about you, but I change the battery in my computer far more often than in my AI transmitter (which is, so far, never in 20+ months, versus twice on the matching computer). And I feel like my computer is far more important than my AI transmitter. So, if I'm willing to have a computer with a battery compartment and an O-ring, then I am dang sure willing to have an AI transmitter that has a battery compartment and O-ring. At least my AI transmitter only have 1 O-ring for the HP port and 1 O-ring for the battery compartment. That is less than the number of O-rings on my BnG SPG. 2 on the spool and 1 at the HP port (and another at the gauge end of the HP hose itself?), plus whatever seals the face of the gauge.

 

[packrat12]

In less than 10 dives, it blew an O-ring on the spool. Why? Because the SPG itself had come loose and gradually unscrewed itself from the HP hose. It was still on there by its last couple of threads, but it was loose enough to pop the O-ring. Fortunately, it happened right after I assembled my rig and turned on the gas, versus happening in the water (and potentially having the SPG finish coming loose and fall off and be lost).

This incident still comes back to improper maintenance of gear and not a failure. It does not matter if you just bought it, had it serviced or have been using it for some time. A good pre-dive check of your gear would have caught that issue. The failure would have been the exact same if it was the transmitter on the 1st stage had been loose.

A lot of if could and maybes. In the real world diving, there are very few SPG failures. I can only think of a couple in 30 years of diving. Electronics and water do mot mix well. Batteries can and do die. Communications fail. Even user knowledge breaks down. There are many potential issues. SPGs have been in use through a significant part of diving. Most technical divers have more than 2 on any one dive, yet this years total for mine is 2 W AI failures, 1 sort of SPG failure. This also corresponds to what I see through out the years. Amongst it, how many times have I seen the DM or first mate brought into the "how do I sync" this question just before splashing in? Obviously the units are not set and forget....

The case of contention is your statement Wireless AI is as good if not better than SPG. I have yet to see that bear out in reality.

 

[doctormike]

The other thing about this endless WAI reliability debate is that almost no one has real data to present.

If 1000 divers are using a system with a 20% failure rate (per unit, not per dive), you will have 800 people here swearing that their WAI system is great and they have no issues with it at all.

 

[doctormike]

Actually, in your example, it is exactly true. You have to give up some other piece of data in order to have that compass displayed - which is just what I said.

OK, that's technically true - I thought that you were referring to the big compass only screen. Although I will say that since the standard Petrel display has 11 data items displayed, giving up one of them for a compass still leaves you with a lot more data than most other computers!

 

[stuartv]

This incident still comes back to improper maintenance of gear and not a failure. It does not matter if you just bought it, had it serviced or have been using it for some time. A good pre-dive check of your gear would have caught that issue. The failure would have been the exact same if it was the transmitter on the 1st stage had been loose.

A lot of if could and maybes. In the real world diving, there are very few SPG failures. I can only think of a couple in 30 years of diving. Electronics and water do mot mix well. Batteries can and do die. Communications fail. Even user knowledge breaks down. There are many potential issues. SPGs have been in use through a significant part of diving. Most technical divers have more than 2 on any one dive, yet this years total for mine is 2 W AI failures, 1 sort of SPG failure. This also corresponds to what I see through out the years. Amongst it, how many times have I seen the DM or first mate brought into the "how do I sync" this question just before splashing in? Obviously the units are not set and forget....

The case of contention is your statement Wireless AI is as good if not better than SPG. I have yet to see that bear out in reality.

I agree. Proper maintenance should prevent almost all problems with either.

For recreational diving, I feel like if you're willing to use a computer with a battery then refusing to use a transmitter because it has a battery is a non sequitur. And in the context of recreational diving, the consequences of transmitter failure are so mild (or the same as for SPG failure, depending on the type of failure), that I just don't feel like that is a reason to say that an SPG is "better'.

I don't say either one is better. I do say that an AI transmitter has less failure points (talking about failure points that could result in loss of gas - trying to compare mechanical versus electronic failure points that result in failure of correct function is a bit meaningless - but there is a reason that just about everything in the world that can be made solid state instead of mechanical is or has been). And I say that AI is more convenient. And it costs a lot more.

Which one a person chooses is, I think, just down to budget and personal preference.

 

[BoltSnap]

That's arguable. Nothing is without a tradeoff. For example, you only have so much screen real estate, so if you put your tank pressure on the screen, you either need a bigger screen or smaller fonts.

There are some things you might need to refer to frequently during even a recreational dive (depth, runtime, NDL), and it's good to have those on your wrist. Tank pressure isn't something that I check that frequently (again, this comes with time and experience), so I would rather not have that piece of data taking up space on my wrist.

Obviously a personal preference, not saying that you are wrong, just that there are different ways of looking at it.

It is, as you and I have said, personal preference for sure. I don't find having all of the information in one screen as difficult to read in general. My D9 is a watch type of computer and now that I am getting wiser and more mature, I find that reading the label at the bottom of the dive time is difficult since I don't wear lenses underwater but my other computers with bigger screen, Vyper Air, is no problem at all. I don't find it cluttered and all critical information for me is there in one screen and one glance. If I am not with students, I almost always have a camera in my hands and I don't have to move my hand anywhere to read my computer with all information.

Again, it is what you are used to and what you prefer, just like there are strange people who prefer to manual gear in their cars instead of automatic

 

[stuartv]

I almost always have a camera in my hands

Reading the display on the back of my camera (i.e. the exposure settings, etc.) is another reason why I would want to have gauge reader lenses in my mask anyway. So, for recreational diving, reading the display on a watch-sized computer is a non-issue (to me).