Tech Diving with computers, air integration?

[dscuba]

So I learned in Intro to Tech that their "do-it-right" way is to have a wrist mounted computer, but never air integrated. However, I've also heard mention elsewhere that tech diving setup shouldn't use a computer, period.

I like the idea of something with air integration because it provides a redundant gauge of the back-air. Even if the air integration feature of the computer were to fail, there's a backup gauge in the regular brass-and-glass SPG on the left post.

So, with redundancy in mind, what kinds of setups are accepted/common in the tech community? If computers are discouraged, or air integration is discouraged, then:
-What's the backup in case the SPG (on the left-post) stops working?
-What's the backup in case the timing device or dive computer stops working?

[vbcoachchris]

So I learned in Intro to Tech that their "do-it-right" way is to have a wrist mounted computer, but never air integrated. However, I've also heard mention elsewhere that tech diving setup shouldn't use a computer, period.

I like the idea of something with air integration because it provides a redundant gauge of the back-air. Even if the air integration feature of the computer were to fail, there's a backup gauge in the regular brass-and-glass SPG on the left post.

So, with redundancy in mind, what kinds of setups are accepted/common in the tech community? If computers are discouraged, or air integration is discouraged, then:
-What's the backup in case the SPG (on the left-post) stops working?
-What's the backup in case the timing device or dive computer stops working?

In general if the SPG stops working you end the dive (You either have enough gas within the team or you don't). The SPG is the back up. Gas and time management is the primary method.

Your back up timing device is on your teammate.

I find air integrated units as a huge added expense, but little value

NTEC requires 2 timing / depth unit per diver.

Scott

[dscuba]

Many thanks for the reply.

Regarding "NTEC requires 2 timing / depth unit per diver": That is to say 2 timing devices and 2 depth devices per diver, right? I guess maybe I haven't been looking hard enough or asking tech divers I've seen around, but what 2nd timing device is typically used? What backup depth gauge do people use? Where are these mounted, stored, or whatever?

[spatman]

often the backup is a simple bottom timer/depth gauge like the uwatec or oms in a wrist mount.

[sheahanmcculla]

Your back up timing device is on your teammate.

I find air integrated units as a huge added expense, but little value

NTEC requires 2 timing / depth unit per diver.

Scott

So if your teammate is a good enough backup, why require 2 bottom timers? Seems overkill to me. It's like having 2 spg's, why?

[loanwolf]

When I dive OC I love to use a gas integrated computer. It enables me to fly OC very similar to how I can on CCR. It calculates my deco for me and also lets me know how much time I have left at the current depth with the gas I have left at my current breathing rate. So I can change my dive plan on the fly and am not stuck with planned tables. It also gives me the ability to say if I am having a great dive and am not cold I can skip using my expensive 50% and 100%. As I can just look and see what I have left for back-gas and the time to surface and as long as the back-gas time is more than the time to surface all is good. I can do all this without really thinking all that much about it. So I will spend the extra time in the water and enjoy myself as I am doing deco. This is a really nice feature when you are on the road and do not have good access to refill 50% and 100%. As it is also reading my breathing rate it will alarm if I am working too hard and it will begin to penalize me if I am working to hard with more deco, a nice safety feature.

I always dive with 2 computers for redundancy on my deco on OC or CCR, then I have emergency tables cut as a worst case scenario that can be ran off a bottom timer.

[vbcoachchris]

Your back up timing device is on your teammate.

I find air integrated units as a huge added expense, but little value

NTEC requires 2 timing / depth unit per diver.

Scott

So if your teammate is a good enough backup, why require 2 bottom timers? Seems overkill to me. It's like having 2 spg's, why?

This is a teamTeam diving vs non team diving question.

I am a team diver, so I would be perfectly fine diving to 300 ft with a teammate, where each of us only had only one bottom timer.

On the other hand I teach NAUI tech and I think NAUI is realistic. Even though I stress team concepts in my class, not every one of my students becomes a team diver.

On a tech dive where your have planned you gas supply correctly, but do not necessarily subscribe to the team concept, the SPG / Bottom timer argument becomes clear.

I can get out of the water safely without an SPG and a teammate. Getting out of the water safely without a teammate and a bottom timer would b trickier. Because NAUI recognizes that this is a situation that is likely to occur. Two bottom timers are required for NAUI Tech classes.

Scott

[boydski]

I like the idea of something with air integration because it provides a redundant gauge of the back-air. Even if the air integration feature of the computer were to fail, there's a backup gauge in the regular brass-and-glass SPG on the left post.

I used to do a lot of deco diving with an air-integrated Vytec on my wrist. Both hands were normally full with my beast of a camera (aka Deathstar) and I found it easy to just roll my wrist and see how much back gas I had left.

Once I started cave diving, the transmitter came off the regulator since I didn't trust a weak bit of plastic to survive an impact with the cave ceiling. I have since found that I don't really miss the air integration or need it.

SPG's rarely fail underwater. They typically fail during pressurization or work for the duration of the dive. The few failures that I have had have always been High Pressure O-rings, which required a post shut down and exit anyway.

As for backup computer/timers, I do carry two when cave diving, since I really don't want to call a dive when one craps out (including someone in my group). It's the same reason I carry three backup lights. Invariably, someone in our group will have a backup light not work or a timer fail after we are already in the water, so I just hand them my extra. Its the same idea as carrying a spare mask, we usually carry one per team.

As Scott pointed out, the spare isn't really necessary and I rarely use a spare here in the Northwest since I do have a spare on my buddy.

YMMV,

[vbcoachchris]

Many thanks for the reply.

Regarding "NTEC requires 2 timing / depth unit per diver": That is to say 2 timing devices and 2 depth devices per diver, right? I guess maybe I haven't been looking hard enough or asking tech divers I've seen around, but what 2nd timing device is typically used? What backup depth gauge do people use? Where are these mounted, stored, or whatever?

NTEC requires two wrist mounted depth and timing gauges. Computers or Bottom timers are fine

Scott

[Joshua Smith]

So I learned in Intro to Tech that their "do-it-right" way is to have a wrist mounted computer, but never air integrated. However, I've also heard mention elsewhere that tech diving setup shouldn't use a computer, period.

I like the idea of something with air integration because it provides a redundant gauge of the back-air. Even if the air integration feature of the computer were to fail, there's a backup gauge in the regular brass-and-glass SPG on the left post.

So, with redundancy in mind, what kinds of setups are accepted/common in the tech community? If computers are discouraged, or air integration is discouraged, then:
-What's the backup in case the SPG (on the left-post) stops working?
-What's the backup in case the timing device or dive computer stops working?

Like the other posters have said- it's really a question of agency training. I would guess that the majority of tech divers out there DO use computers. There's a pretty large market for tech computers as a result- VR-3s, X-1s, Shearwaters, Cochrahns, and a hadfull of others. None of the ones I just named are air integrated, however. I guess the assumption is that we'll just use SPGs, and as far as I'm aware, SPGs don't fail all that often. Sure, they fail once in a while, but not with enough frequency to concern me very much.

I like having a computer. I always do deco dives with tables- well, almost always. Below 200', I definitely have tables. Recently, I tried to dive a shipwreck in ~290 fsw. Viz was fine down to about 270', where it went to virtually nothing. After a minute on the bottom, I thumbed the dive. I hadn't brought any tables for one minute of bottom time. So, I followed my computer-generated stops up to the surface. If the computer had failed, I would have been compelled to follow my shortest bottom time table, which wouldn't have been much fun. Plus which, I like to use the computer as a sanity check- the way I have mine set up, it follows my deco tables very closely.

[LCF]

One of the things about tech diving . . . you plan your gas. Before you ever get in the water, you know roughly how much gas you are going to need for each phase of the dive, and you know you are carrying more than enough gas to get the job done. As stated, if your SPG goes down (and I've never had one fail DURING a dive) you abort, which means you have even MORE gas to get out.

Some people just like being able to see their pressure on their wrist (my husband does) and honestly, the transmitter, in a non-overhead environment, doesn't add any more failure points than a port plug. But they can be temperamental about syncing and they are very expensive (and you still have to have an SPG) so in general, most of us would rather put the money into helium.

[Peter Guy]

Although I have several "technical certs" I do not consider myself anything more than a baby tech/cave diver -- at best. I also don't use the "brass and glass" SPG on my backgas. Since I have a Vytec and a couple of transmitters, I keep one on my right post (and pointed down so it won't catch on anything -- IF I hit the cave ceiling hard enough to damage it, I'll have a lot more problems on my hand than that!) and I use a Cobra on my left, clipped to my left hip D-ring.

Why a Cobra? a. I bought it during my OW class so I have it. b. I use it to capture/download my dive info and I like the software. c. It is a redundant source of Depth/Time in addition to PSI (yes, gauge mode). d. Has it given some instructors fits? YUP -- and one of them (ahem!) even made me replace it with a Brass & Glass SPG due to some nonsense about "NTEC Rules!" (Because I didn't have my Cobra, I was unable to capture info about a very important training dive - I've always wanted to see the profile--but that's another sad story.)

Had I not already HAD a Vytec/transmitter and a Cobra would I have purchased them for tech diving? Hell no - but unless and until they die, I'll use them.

[Mattleycrue76]

It calculates my deco for me and also lets me know how much time I have left at the current depth with the gas I have left at my current breathing rate.

So does your computer account for an oh s**t moment that doubles your gas consumption at the worst possible moment?

[Joshua Smith]

It calculates my deco for me and also lets me know how much time I have left at the current depth with the gas I have left at my current breathing rate.

So does your computer account for an oh s**t moment that doubles your gas consumption at the worst possible moment?

Yep- when your SAC rate triples, your available time is cut by 66%!

[Paulicarp]

honestly, the transmitter, in a non-overhead environment, doesn't add any more failure points than a port plug.

I'm probably over thinking this and splitting hairs, but I believe a transmitter does at least pose a higher risk of failure than a port plug, if not more failure points. Maybe it’s beside the point you’re making Lynne, but the transmitters that I’m familiar with are somewhat bulky and liable to catch hoses. Compared to a plug, they are also much more likely to break off or be inadvertently backed out of a port by bumping into another diver at the right angle. I don’t have anywhere near the experience that you guys do, but I have seen them fail this way. Please don’t think I’m going to the extreme of saying they’re death trap like the dongly wonky knobs on butt dumps (lol), but I do think they do pose a more significant risk of failure than a mere plug.

[ArcticDiver]

Yet another perspective but to illustrate there is no "right" answer. There is only the answer you and your dive buddies choose to use and are comfortable with.

Always two or more ways to measure or a rock solid fallback for every critical element of a dive. Your buddy never counts as a rock solid backup. After all, under worst case scenarios your buddy just had a totally unexpected and unforseen problem and dropped into the abyss where you couldn't go to recofer the body. In other words buddy diving is fun but brings with it some negatives that are not commonly thought of. To use the old pilot's thing: Two airplanes bring twice as many opportunity for problems and the other guy may fly into you. On the other hand the other plane may save your butt when he protects your six.

The rest is economics. Can you afford to buy air integration? If you can it is The Way to go. In my personal case my air integrated rig died, I"m not diving as much as I did and so could not justify the expense to replace it. I still have multiple computers and a watch and tables.

The metering machines don't know whether you are in open water or in an overhead environment. Neither should you. All dives are overhead dives and all dives are decompression dives. Follow that and you will be prepared for anything at any time.

[CaptnJack]

A) depth/time/gas are all related to one another so if you know 2 you have a pretty good idea about the third.

B) I've had a bunch of spgs fail, cracking gas and bubbling spool orings. In both cases they continue to work for the remainder of the dive. Even the leaky ones let a very small amount of gas past the orifice so there's rarely a need to shut down the left post. Combined, there's little need for backup spgs.

I've never used a computer, just a uwatec puck. Being a sealed unit about the only failure is a dead battery, they start to read "6ft" on the surface when the battery goes (roughly after 7-10yrs of use). On the off chance this happens on a dive (it did with my old aladin tec 2g gauge) I just let my buddy call the rest of the deco.

[vbcoachchris]

One of the things about tech diving . . . you plan your gas. Before you ever get in the water, you know roughly how much gas you are going to need for each phase of the dive, and you know you are carrying more than enough gas to get the job done. As stated, if your SPG goes down (and I've never had one fail DURING a dive) you abort, which means you have even MORE gas to get out.

Some people just like being able to see their pressure on their wrist (my husband does) and honestly, the transmitter, in a non-overhead environment, doesn't add any more failure points than a port plug. But they can be temperamental about syncing and they are very expensive (and you still have to have an SPG) so in general, most of us would rather put the money into helium.

[vbcoachchris]

Although I have several "technical certs" I do not consider myself anything more than a baby tech/cave diver -- at best. I also don't use the "brass and glass" SPG on my backgas. Since I have a Vytec and a couple of transmitters, I keep one on my right post (and pointed down so it won't catch on anything -- IF I hit the cave ceiling hard enough to damage it, I'll have a lot more problems on my hand than that!) and I use a Cobra on my left, clipped to my left hip D-ring.

Why a Cobra? a. I bought it during my OW class so I have it. b. I use it to capture/download my dive info and I like the software. c. It is a redundant source of Depth/Time in addition to PSI (yes, gauge mode). d. Has it given some instructors fits? YUP -- and one of them (ahem!) even made me replace it with a Brass & Glass SPG due to some nonsense about "NTEC Rules!" (Because I didn't have my Cobra, I was unable to capture info about a very important training dive - I've always wanted to see the profile--but that's another sad story.)

Had I not already HAD a Vytec/transmitter and a Cobra would I have purchased them for tech diving? Hell no - but unless and until they die, I'll use them.

[Geek]

It calculates my deco for me and also lets me know how much time I have left at the current depth with the gas I have left at my current breathing rate.

So does your computer account for an oh s**t moment that doubles your gas consumption at the worst possible moment?

Yes

[CaptnJack]

It calculates my deco for me and also lets me know how much time I have left at the current depth with the gas I have left at my current breathing rate.

So does your computer account for an oh s**t moment that doubles your gas consumption at the worst possible moment?

Yes

warpspeed deco to get out of the water before you go outa gas?

[LCF]

The way Peter has his transmitter mounted on his doubles, it's pointed straight down at the manifold. It would take something very strange to hit it. I really don't think it presents any more of a leak hazard than a port plug, and it would take something very convoluted to get entangled around it -- your first stages are more of a hazard than it is.

Which is not to say I think they're desirable. Note that I never bought one, when the Vytec was MY computer. But I don't think you're inevitably going to die if you use one, either.

Now, when it comes to the Cobra . . . Well, I'm with Scott.

[Geek]

It calculates my deco for me and also lets me know how much time I have left at the current depth with the gas I have left at my current breathing rate.

So does your computer account for an oh s**t moment that doubles your gas consumption at the worst possible moment?

Yes

warpspeed deco to get out of the water before you go outa gas?

Count down to kiss my ass good bye..... in digital OLED beautiful color no less...

[loanwolf]

It calculates my deco for me and also lets me know how much time I have left at the current depth with the gas I have left at my current breathing rate.

So does your computer account for an oh s**t moment that doubles your gas consumption at the worst possible moment?

Josh
Cochran makes an integrated 3 gas computer and the new one that Laura in reping is also integrated. Her's is even buddy integrated so you can read your buddies and all your deco/bailouts as well on the same screen if you want.

Matt
yes it does, if you have a oh shit moment and your air consumption goes up an alarm will sound and it will be telling you your consumption rate is high and changes the gas time at the moment and starts to penalize you with more deco unless you calm down and lower your breathing rate.

[Waynne Fowler]

The few failures that I have had have always been High Pressure O-rings, which required a post shut down and exit anyway.

Train?...... Why do I hear a train?