Do I really need an expensive dive computer??

[gcarter]

Immediately after my September cert, I asked my wife for a dive watch for Christmas. I figured I would dive tables, a computer could wait. I also figured I would rent gear - especially tanks!!

Christmas 2010 saw me with the dive watch I had asked for, an Oceanic Veo 2.0, SeaQuest Balance BCD, and a full Apeks ATX40 reg set with console. Before spring I had bought my wet suit and the downward spiral was well underway. I have never done a dive since OW without all my own gear, other than tanks and weights. 7 tanks in the garage (re-sold 2 others), steel and aluminum plates with wings, added an Apex TX50 reg set, a Petrel 2, etc.

What I have learned is that a) I really like diving my own gear and b) it doesn't matter what anybody else thinks of my choices. I like my watch, although I upgraded to an oversized one this Christmas, my other one was on over 300 dives with me. I never had to fall back on it, unlikely that I ever will. My Veo 2.0 was more than enough computer for my diving, but I could afford the Petrel 2, I loved the screen for my eyes, and thought I deserved a new shiny

 

[JamesBon92007]

I use an AI computer and also have an SPG with depth guage and wear a dive watch. And carry a pony. It's not that I distrust the computer, I like backup systems. Stuff happens. I like the computer's ability to adjust based on real time, thus adding to my dive time. But they can fail. The SPG can also fail. So can my primary air supply. So I carry backups.
If the SPG or computer failed, the other allows me to finish the dive safely, rather than have to abort and surface. If the primary air fails on the other hand, dive is over, but the pony gets me home without a CESA.

Are you referring to a SPG on a HP hose, or an AI computer? I don't recall ever seeing a SPG suddenly fail. The worst I've seen is a slow leak might develop and a stream of bubbles would form which could sometimes be reduced or even eliminated by simply rotating the gauge. Of course, at that point, it's time for some service before the next dive. Actually it should have been serviced before it got to that point.

 

[EFX]

In these various posts when talking about dive computers inevitably someone posts that their computer's battery went dead, hence the reason for a backup. But, amazingly no one wears a backup bottom timer and even more amazing the bottom timer's battery never goes dead. Mmmm......interesting.

 

[woodcarver]

That's what the watch is for. Always set the bezel right before descent. I've never seen an actual bottom timer, but have read some descriptions, some of which described having to wind it. Sort of like a manual watch? Can you post a pic?

 

[woodcarver]

Are you referring to a SPG on a HP hose, or an AI computer? I don't recall ever seeing a SPG suddenly fail. The worst I've seen is a slow leak might develop and a stream of bubbles would form which could sometimes be reduced or even eliminated by simply rotating the gauge. Of course, at that point, it's time for some service before the next dive. Actually it should have been serviced before it got to that point.

I've never seen a scuba SPG fail, just read about it. But I have seen pressure gauges on welding tanks fail-needles stick, something in the orifice causing a bad read (would think the latter to be highly unlikely with scuba), springs fail.
Again, it's not something I would think is likely, but that's the whole concept of redundancy.
Edit: I should clarify, I think it more likely the AI DC would fail, lose contact with tank or something, rather than the SPG on a hp hose from the 1st stage

 

[JamesBon92007]

In these various posts when talking about dive computers inevitably someone posts that their computer's battery went dead, hence the reason for a backup. But, amazingly no one wears a backup bottom timer and even more amazing the bottom timer's battery never goes dead. Mmmm......interesting.

Well, there are wind-up bottom timers and there are digital bottom timers. The battery never goes dead on the wind-up kind

Or should I say there were bottom timers. I'm not sure if anyone makes them any more.

 

[AdivingBel]

Sorry guys...but if I have to have one or the other, I'll take an SPG every time over a depth gauge. I can estimate my depth, but running out of air will kill you. Of course I'm a warm water diver so my viz is usually pretty good. IMHO, YMMV.

 

[gcarter]

Sorry guys...but if I have to have one or the other, I'll take an SPG every time over a depth gauge. I can estimate my depth, but running out of air will kill you. Of course I'm a warm water diver so my viz is usually pretty good. IMHO, YMMV.

Curious. How do you estimate your depth with reliability?

 

[JamesBon92007]

That's what the watch is for. Always set the bezel right before descent. I've never seen an actual bottom timer, but have read some descriptions, some of which described having to wind it. Sort of like a manual watch? Can you post a pic?

Here's a pic I grabbed online:

Mine is just like this one. You pull up on the button to reset it to zero. You push the button down to wind it and to dive. It starts and stops automatically at about 8 feet deep. There is a diaphragm on the back that you can push to get the second hand back to zero, if you are that anal

They are occasionally available on eBay etc but usually I see them along with a gauge console. Unless it looks like it's really beat up it probably still works. They have a slot in the back for a wrist strap or you can use a couple of cable ties to attach it to a console or whatever. You just need to make sure the button on top is accessible.

Mine seems to be a tiny bit "conservative" in that on a 65 or so minute dive it reads about one minute more than my digital watch.

 

[JamesBon92007]

Sorry guys...but if I have to have one or the other, I'll take an SPG every time over a depth gauge. I can estimate my depth, but running out of air will kill you. Of course I'm a warm water diver so my viz is usually pretty good. IMHO, YMMV.

Have you ever ran out of air? I have several times and was conscious that it was going to happen. I was, however, in open water and never deeper than about 50 feet. I'm pretty sure I'm not dead but my girlfriend might not agree with me (on some days). It becomes difficult to breathe when your air drops below your IP. At that time you know that you have about 130 psi in your tank. As you ascend you can get enough air to continue to breathe fairly normally, at least with any regulator that I've used. But, of course, once you get to the surface you may change your mind if you are one of those people who doesn't believe in snorkels I don't recommend continuing to suck the very last bit of air from your tank because at some point you will no longer get a full breath and that's when I would say you are "out of air." If you are in a cave or inside a shipwreck then it's time to hope that your buddy, who started out with the same amount of air, still has some in his/her tank and either has an octopus or knows how to buddy breathe.

As for estimating depth, I used to dive the same fairly shallow locations many times and knew the depth from someone else' gauge but didn't need one under those circumstances. But if I am diving past about 50 or 60 feet I definitely want to know my depth within a foot or two.