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MxDiver
07-28-2007, 14:42
Considering the cost difference between an AI vs., a non-AI computer, I'm debating were the advantages the AI computer provides are really worth it.
For example I can purchase two Nitek duo computers for the price of a single VT3 with one transmitter, which are the front runners on my list of options so far.
So I can have my main and back-up non-AI computers for the price of a single AI one.
Which way would you go, and why?

thesmoothdome
07-28-2007, 14:52
I never thought I'd go AI, but I did. I really like that it calculates my SAC rate and gives me air time remaining. Is it needed? No, but it's nice.

MxDiver
07-28-2007, 15:10
I can calculate the SAC with the suunto, just not on real time, in the dive manager you can type your start and end pressure and it will do the rest for you, I'll have to check if the same applies to the Nitek software.

Ajuva
07-28-2007, 15:22
Only you can decide what works best for you.

I went AI with the Atom 2.0 and just cant fault it.

I cant really justify the cost difference but having used it for a while now I can see the benefit to having these functions literally to hand.

Ajuva

tc_rain
07-28-2007, 15:25
I like AI

awap
07-28-2007, 16:24
I guess if mindless SAC and ATR calculations are worth $100+ each then AI may be the answer.

I went AI once. It was a Scubapro EDI so none of the bells and whistles - just basic feedback along with tank pressure. When I again upgraded to nitrox, I went back to my 35 year old SPG and a simple wrist computer. If I ever need to upgrade again, I'm pretty sure I'll be staying with my old reliable SPG.

medic001918
07-28-2007, 18:11
My first computer was AI, and I've been happy with how it works. However, I'm switching to a non-AI computer since I like the idea of a wrist mount, but I don't like the idea of the wireless transmitter. It seems like the potential is there for too many issues with it. Damage, interference, etc. I could use a transmitter and an SPG, but really I think the SPG alone will be sufficient. I can do the SAC calculations after the dive if I feel so inclined. Or I could just download the dive and get the information that way.

Shane

thesmoothdome
07-28-2007, 18:22
I guess if mindless SAC and ATR calculations are worth $100+ each then AI may be the answer.

I went AI once. It was a Scubapro EDI so none of the bells and whistles - just basic feedback along with tank pressure. When I again upgraded to nitrox, I went back to my 35 year old SPG and a simple wrist computer. If I ever need to upgrade again, I'm pretty sure I'll be staying with my old reliable SPG.

LOL...not trying to start an argument here, but "mindless" sorta implies that it's better to use your brain for the calculations than to let a computer do it? Not really seeing the logic there. I will say that you're better at math than I am :smiley32:. For me, the extra $100+ spread out over the life of the computer, which will most likely work out to pennies per dive, is definately worth sparing me the embarrasment of not being able to do the math. :smiley20:

Splitlip
07-28-2007, 19:14
The next logical question here will be "should I have a backup SPG". The answer will be yes. Then you know what the next comment will be.

Edit: I lost my popcorn.

JahJahwarrior
07-28-2007, 19:46
What are your diving plans for the future? If you plan to do technical diving, then you will definitely need a backup SPG. And if you need to have the SPG there anyways, what is the point? I'd go non-AI, but that is just me. If you have th emoney to spend, spend it wherever your heart desires. non AI, AI, heck spend it on (as Frank Gilbreth so well put it,) "mumblety peg, if that's where your heart lies."

Divingguy
07-28-2007, 21:11
I have both a VT Pro and an Atom 2 running off of the same transmitter, AND I do also use an Aeris nav-console w/ compass. I have NEVER had a problem with the AI, and find the real-time data very convenient and useful during multi-level and deep dives.

awap
07-28-2007, 21:19
I guess if mindless SAC and ATR calculations are worth $100+ each then AI may be the answer.

I went AI once. It was a Scubapro EDI so none of the bells and whistles - just basic feedback along with tank pressure. When I again upgraded to nitrox, I went back to my 35 year old SPG and a simple wrist computer. If I ever need to upgrade again, I'm pretty sure I'll be staying with my old reliable SPG.

LOL...not trying to start an argument here, but "mindless" sorta implies that it's better to use your brain for the calculations than to let a computer do it? Not really seeing the logic there. I will say that you're better at math than I am :smiley32:. For me, the extra $100+ spread out over the life of the computer, which will most likely work out to pennies per dive, is definately worth sparing me the embarrasment of not being able to do the math. :smiley20:

Maybe I am. Pennies per dive would mean you are talking about doing on the order of 10,000 dives on that computer.

Mindless may not have been the best choice of words. Useless would probably have been better applied to ATR. I've calculated my SAC a few times and it is useful to have a good estimate for gas planning. It is not that hard to get a good estimate for gas planning. Beyond that it really is not a terribly useful statistic unless you want to study and analyze the variables that effect gas usage. I'd rather enjoy the dive.

awap
07-28-2007, 21:24
I have both a VT Pro and an Atom 2 running off of the same transmitter, AND I do also use an Aeris nav-console w/ compass. I have NEVER had a problem with the AI, and find the real-time data very convenient and useful during multi-level and deep dives.

What AI computer stats do you find useful during a multi-level and a deep dive, and how do you use them during that dive?

Divingguy
07-28-2007, 21:38
The real-time updating of ATR and DTR, especially when fighting a current, or consuming far more air at depth, helps with adjusting profiles in mid-dive. Certainly can be done in head, or manually, but nice info to have.

awap
07-28-2007, 21:45
The real-time updating of ATR and DTR, especially when fighting a current, or consuming far more air at depth, helps with adjusting profiles in mid-dive. Certainly can be done in head, or manually, but nice info to have.


Do you plan your dives based on ATR and DTR (what exactly is that) or do you plan based on tank pressure (and/or volume)?

thesmoothdome
07-28-2007, 21:56
I'd assume it's Dive Time Remaining. It's definately nice to have more information at your fingertips than less. Care to share the point your trying to make Awap?

awap
07-28-2007, 21:59
I'd assume it's Dive Time Remaining. It's definately nice to have more information at your fingertips than less. Care to share the point your trying to make Awap?


I figured that out but unsure of exactly hoew it differs from the No Deco Limit or ATR. ATR, as I understand it is the time remaining at the current depth until you will reach a user preset tank pressure. Is that correct?

The point I am headed toward is that most people will plan their dives based on gas pressure (sometimes volume). And if that is the basis of the plan then that is the ionfo you need to follow or adjust that plan. I dove with a guy who kept getting ATR and NDL mixed up. It was not funny.

thesmoothdome
07-28-2007, 22:13
Not sure to be honest. Again, all I can make are assumptions and I'd assume he's relating it NDL since he mentioned ATR. Yes, you're correct in thinking that the ATR is calculated to a user set tank pressure. Mine defaults to 500psi. If anything the ATR is nice to see just as reminder as to how much time you have left at a given depth. Gives you incentive to head for the shallows to stretch the dive time out.

awap
07-28-2007, 22:31
If anything the ATR is nice to see just as reminder as to how much time you have left at a given depth. Gives you incentive to head for the shallows to stretch the dive time out.

Just my point. That kind of thing is normally worked out in the dive plan based on tank pressure (or volume). Even if it is as simple as 60ft for 35 minutes or 1200psi. Then 10 minutes working to 20 ft arriving with at least 700psi. Burn excess gas at 20 ft and continue ascent at 700 psi....

How do you work ATR into a plan like that?

MxDiver
07-29-2007, 00:38
What are your diving plans for the future? If you plan to do technical diving, then you will definitely need a backup SPG. And if you need to have the SPG there anyways, what is the point? I'd go non-AI, but that is just me. If you have th emoney to spend, spend it wherever your heart desires. non AI, AI, heck spend it on (as Frank Gilbreth so well put it,) "mumblety peg, if that's where your heart lies."

Yes, I do plan on doing technical diving, which is, as a matter of fact, what got me looking for a new computer, Right now I have Suunto Mosquito. Trimix is not being considered right now, only advanced nitrox.
Personally I wouldn't dive without an SPG regardless of what computer I have, my console with a depth gauge and SPG could be welded to my first stage as far as Iím concerned.
My options right now are an AI computer and bottom timer as a back up, or two non AI computers which can also work as bottom timer if required.

cummings66
07-29-2007, 08:26
For my techical diving course this is the requirements. Doubles or a large single with H valve, two first stages with regulators on it, and drysuit. Dive plans will be done by table and followed using manual methods. He see's nothing wrong with computers but it's not something needed.

I dive AI, VT3 for what it's worth, and on the H valve one HP port on the DS4's will be the SPG and the other the AI transmitter. My VT3 supports multiple mixes up to 100% and I know how to switch tanks on it. It's not needed, nor will it ever be used to plan things, but I will play with it primarily to keep track of tank pressures when I switch without having to write those numbers down.

For me the only time the DTR or ATR comes into play is on a shallow dive that I didn't really plan. So if I'm less than 30 feet deep just playing around it's kind of nice, but completely unnecessary because I already know my rock bottom for 30 feet and go by that by preference.

BSea
07-29-2007, 09:14
Not sure to be honest. Again, all I can make are assumptions and I'd assume he's relating it NDL since he mentioned ATR. Yes, you're correct in thinking that the ATR is calculated to a user set tank pressure. Mine defaults to 500psi. If anything the ATR is nice to see just as reminder as to how much time you have left at a given depth. Gives you incentive to head for the shallows to stretch the dive time out.

On the oceanic computer I had, DTR was exactly that. It might be because of air remaining, or it might be because of NDL were being reached, or PO2 was being reached. The computer decided based on which would be reached 1st.

cummings66
07-29-2007, 11:35
I know on the Ocenic VT3 the DTR is not down to the minute accurate so please don't count on it. I've had it hit 0 before and still had more than enough air, plus my O2 and NDL were fine. It has only happened on a shallow dive however. Down deep when it says 5 minutes remaining you have 5 minutes.

Either way, it's bad form to let the computer plan your dive for you.

thesmoothdome
07-29-2007, 13:54
If anything the ATR is nice to see just as reminder as to how much time you have left at a given depth. Gives you incentive to head for the shallows to stretch the dive time out.

Just my point. That kind of thing is normally worked out in the dive plan based on tank pressure (or volume). Even if it is as simple as 60ft for 35 minutes or 1200psi. Then 10 minutes working to 20 ft arriving with at least 700psi. Burn excess gas at 20 ft and continue ascent at 700 psi....

How do you work ATR into a plan like that?

It doesn't. Again, it's just a reminder with a built in safety factor of 500psi. It can also be used to learn about the physics involved in another way too.

Sure, your OW class explains Boyles Law as pressure increases, density increases and volume decreases and sure after enough explanation about ATM most people have a rudimentry understanding. Wanna make it more real though?

Hand someone a SPG and take them to 4ATM. Does the PSI remaining change? Give someone an AI computer with ATR calculations and show them that what was 20 minutes on the surface is now 5 minutes at 4ATM and the law is driven home.

Guess it's just the teacher in me :smiley2:. I've always loved seeing ideas presented in different manners.

thesmoothdome
07-29-2007, 13:56
Not sure to be honest. Again, all I can make are assumptions and I'd assume he's relating it NDL since he mentioned ATR. Yes, you're correct in thinking that the ATR is calculated to a user set tank pressure. Mine defaults to 500psi. If anything the ATR is nice to see just as reminder as to how much time you have left at a given depth. Gives you incentive to head for the shallows to stretch the dive time out.

On the oceanic computer I had, DTR was exactly that. It might be because of air remaining, or it might be because of NDL were being reached, or PO2 was being reached. The computer decided based on which would be reached 1st.

That makes a lot of sense. Instead of worrying the diver with a bunch of variables that contain conflicting information, it simplifies it to show how much actual dive time is remaining.

awap
07-29-2007, 14:36
That makes a lot of sense. Instead of worrying the diver with a bunch of variables that contain conflicting information, it simplifies it to show how much actual dive time is remaining.

Would that bunch of variable that contain conflicting info include basic parameters like gas remaining (Pressure or volume), NDL, and current depth? And really all you need is DTR? What does it mean when DTR is zero?

The way to tell how much dive time is remaining is you subtract your elapsed dive time from your PLANNED dive time. Then you may also want to verify your NDL and your remaining gas are also as PLANNED. And if you planned based on ATR or DTR, then verify that those parameters are as planned.

Plan your dive. Dive your plan. (Adjust as necessary.)

thesmoothdome
07-29-2007, 14:43
That makes a lot of sense. Instead of worrying the diver with a bunch of variables that contain conflicting information, it simplifies it to show how much actual dive time is remaining.

Would that bunch of variable that contain conflicting info include basic parameters like gas remaining (Pressure or volume), NDL, and current depth? And really all you need is DTR? What does it mean when DTR is zero?

The way to tell how much dive time is remaining is you subtract your elapsed dive time from your PLANNED dive time. Then you may also want to verify your NDL and your remaining gas are also as PLANNED. And if you planned based on ATR or DTR, then verify that those parameters are as planned.

Plan your dive. Dive your plan. (Adjust as necessary.)

I knew after I typed the word "conflicting" you'd catch me on it Awap. I don't know about the oceanic, but I know a lot of computers simplify things by showing the most "pertinent" information on the screen at the time and you can scroll through for the other info. If you want it, it's there.

As for basic info like gas remaining and depth, from the computers I've seen, that info is always on the screen.

texdiveguy
07-29-2007, 14:46
Simple: non-air integrated.

tc_rain
07-29-2007, 15:00
I know on the Ocenic VT3 the DTR is not down to the minute accurate so please don't count on it. I've had it hit 0 before and still had more than enough air, plus my O2 and NDL were fine. It has only happened on a shallow dive however. Down deep when it says 5 minutes remaining you have 5 minutes.

Either way, it's bad form to let the computer plan your dive for you.

I have the Aeris Elite and you can set a reserve air amount that is not included in your DTR. This could also be the case with the VT3 but I am not for sure.

thesmoothdome
07-29-2007, 19:50
I know on the Ocenic VT3 the DTR is not down to the minute accurate so please don't count on it. I've had it hit 0 before and still had more than enough air, plus my O2 and NDL were fine. It has only happened on a shallow dive however. Down deep when it says 5 minutes remaining you have 5 minutes.

Either way, it's bad form to let the computer plan your dive for you.

No, it shouldn't be the blindly followed. Rather, the information being presented should be synthesized and a decision should be made by you. I definately am not going to discount the information presented to me though. If my SPG is telling me that i have enough gas but my comp. is telling me I'm down to 0 DTR, I'm going to either figure out why I have 0 DTR and make a decision as to what to do or decided there's a mistake somewhere and end my dive because my computer isn't acting right.

thor
07-30-2007, 15:02
I have an Aeris Elite integrated. I like one less hose. I bought it when I first started diving b/c I really didn't know how much air I was using, or how fast. I love the instant feedback.

TxHockeyGuy
07-30-2007, 16:01
I dive an Aeris Elite air integrated wireless computer and I like it, but not for the reasons most do. I like it because when I download it to my computer I now have my starting and ending pressures and it will compute my SAC rate for me. The air time remaining feature underwater is not terribly useful to me, I could look at my gauge and know how long I have give or take a few minutes based on my depth and work load, no complicated math required I just guestimate. Basically I'm lazy and don't like to write stuff from my dive down until usually weeks later I like that it records my tank readings, it lets me see how I'm progressing with getting my SAC lower.

bperrybap
07-30-2007, 16:07
That makes a lot of sense. Instead of worrying the diver with a bunch of variables that contain conflicting information, it simplifies it to show how much actual dive time is remaining.

Would that bunch of variable that contain conflicting info include basic parameters like gas remaining (Pressure or volume), NDL, and current depth? And really all you need is DTR? What does it mean when DTR is zero?

The way to tell how much dive time is remaining is you subtract your elapsed dive time from your PLANNED dive time. Then you may also want to verify your NDL and your remaining gas are also as PLANNED. And if you planned based on ATR or DTR, then verify that those parameters are as planned.

Plan your dive. Dive your plan. (Adjust as necessary.)

I think what thesmoothdome was trying to say is
that there are several air-integrated dive computers out
there that present both an NDL time as well as an ATR time on
the screen at the same time. My feeling is that this is bad.
The Oceanic/Aeris computers do not do this. While they
do allow you to access these different times, they normally
only present a DTR which is the shortest time. This ensures
the diver doesn't accidentally look at and use an incorrect
time. While you can argue that the diver should be
smart enough to understand his computer, many,
for a variety of reasons, from vision to lack of familiarity
with the computer, don't. I believe that having a simple
"DTR" is very useful.

For the Oceanic/Aeris computers when DTR goes to zero
it means the dive is now over. Do a controlled ascent and
your safety stop, and you "should" exit with your
selected end pressure.
While I would never want to depend on DTR to determine
when I start my ascent, I think it is a useful tool,
especially since an alarm can be programmed based on it
which could alert someone who is off shooting
video while following a turtle into a current at 80 ft
and burns through most of their air in just a few minutes.
(I have watched this happen in Cozumel)

Air integrated also allows you to program in simple things
like a turn pressure alarm. Again, a useful feature
especially for photographers who may be temporary
distracted.

----

"Adjust as necessary". Yep that is the key thing here.

Your methodology above is "ideal" but the real world
is seldom ideal. Lots of things can happen that will
require tweeking/adjusting your actual dive away from your plan.
I believe that while not absolutely necessary, having
a DTR that takes into consideration ATR is a very useful
tool. Its one more piece of information that can be used
to modify your dive during the dive when the dive
has deviated away from the plan.
For most folks the computer will calculate an ATR
that is more accurate and reliable than the diver can
compute in his head.

For newer divers I believe that AI computers can provide
some level of comfort and help them relax which
translates into longer dives and more enjoyment for them.
For newer divers (who are Air limited vs NDL limited)
or divers that don't dive very often
and have SAC rates that are all over the map,
I believe it can help them determine
how much air time they have left during the dive which again will
help them enjoy their dives more.
(either by extending their dives, or reminding them
to come up sooner than expected)

For old salts that have been diving for years or
divers that have a very good understanding of their
air consumption and know how to plan their gas
management, having an Air integrated computer
that provides air time remaining
may not be worth the extra expense.

BTW, from reading many of the posts over on SB,
(which I admit isn't very scientific), it appears that
not many folks know enough about their air consumption
rates and gas planning to be able to plan their bottom
times or profiles taking into consideration gas consumption.

To me the "Air Integrated" feature is a value proposition.
Obviously, if it was free, I bet most folks would get it.
It is not free, so now it becomes how much is it worth?
Well, that depends on many factors and becomes a
personal decision.

For me, I like it and find it useful. Others may not.
The beauty of some of the newer hoseless units is
that you can get them either way.

--- bill

cummings66
07-30-2007, 18:53
I have an Aeris Elite integrated. I like one less hose. I bought it when I first started diving b/c I really didn't know how much air I was using, or how fast. I love the instant feedback.

I usually reply when I see postings like this, and it's not your fault. When divers are taught how to dive they're never taught the skills to figure out what you didn't know and it's vital to know that info.

You honestly need to know your consumption rate (which you should due to the computer) and then use that to figure out how much air you will use on a dive.

I play a fun game. I plan the dive, figure out how much air I'm going to need and then dive it. I try to see how close the computer and I get to being in sync. It's fun to see how close it comes.

cummings66
07-30-2007, 19:05
BTW, from reading many of the posts over on SB,
(which I admit isn't very scientific), it appears that
not many folks know enough about their air consumption
rates and gas planning to be able to plan their bottom
times or profiles taking into consideration gas consumption.


Reading many postings here I get the same feeling. I think this is a skill that should be taught in OW, how many divers go OOA because they don't understand the amount of air they really need and don't look at their SPG often enough because they don't understand they're going to use more air the deeper they go. I mean understand it in a way that translates to being able to plan on it.

Basically you get taught Boyles Law as it applies to diving in a way that doesn't help you. Who cares if that soda bottle you put air in at 33 feet is full at the surface and vice versa. A person needs to know that in relation to their air usage not how it affects a soda bottle.

So if I use .6 cf per minute at the surface what do I use at 33 feet? That's the kind of stuff a diver should learn in OW, not to mention how to figure out the .6 cf bit. I've seen too many divers go OOA because they're buddy doesn't check on them, they don't check their SPG and they have no clue how much air they consume.

When I dive with a new diver now I go over the details OW left out, I then watch their SPG as if it was my own (without them knowing it most of the time) and I ask them every so often for their pressure. I know it ahead of time but I want them to think about it. I'll usually signal them to go up based on their pressure most of the time before they're ready to go up. Since I've started doing that I've never had a buddy go OOA on me. I had one go OOA once before when I trusted them to tell me what was going on. I've seen lots of other buddies go OOA though.

It's sad and IMO there's no need for it. A computer is nice and is a crutch for new divers, but they really need to figure this out manually and then use the computer to verify it if need be. Those skills are basic, and every diver needs to know them, and they don't.

OK, I'm off my soapbox for now.

MxDiver
07-30-2007, 19:47
Cummings66

I agree with you, I did not get to go into details of air consumption and dive planning until I took the deep diver specialty course. Before that my planning would be done merely on NDL or "whenever" I reach a given PSI number, usually around 700 to do a 3 minute safety stop and come up with 500.

Ruminari
07-30-2007, 20:05
I spent the extra and got a Oceanic Datamx Pro Plus 2 and have loved every minute of diving with it. Although I still regularly check my air supply it's always nice to have redundancy and if for some reason I forget to check it I know the computer has my back.

thesmoothdome
07-30-2007, 20:44
It bothers me that there's a sense of 'if you don't do it my way, you'll die" in Mathew's statements. Let's be real, a casual diver wh has been trained properly in their OW class may not know how to calculate their SAC rate and what it means to their dive, but they should know 1) you use more air the deeper you go. 2) you need to monitor your SPG on a regular basis. 3) There's never an excuse to run out of air on a dive.

Cummings66 also said:
"I know it ahead of time but I want them to think about it. I'll usually signal them to go up based on their pressure most of the time before they're ready to go up."

I'd assume that ascent time/pressure would have been predetermined before the dive in the plan that you talk about making.

In all honesty, and with all due respect, if someone is going to "tell me what my OW class didn't" right before we dive together, and I don't know that person, I'm probably not going to take to well to that. As a new diver, I'm probably focused on what I know, not taking in more information.

As a teacher, an ex-instructor, and a coach, I'm going to make sure that I don't overload my charge with information that they're not going to be able to synthesize in time for them to utilize during the present scenario. I'm also going to make sure that even though I'm keeping a closer eye on them, they're gaining skills and not becoming dependent on me. Rather than ask them for their air pressure, I'm going to give them mine and wait for the response back. Rather than forcing them to abort a dive earlier than we had planned, I'm going to put them in a position where we end as planned.

Like you, I've got a few dives under my belt, even if I have taken the last 10 years off. I've never had a buddy or a student run OOA. That's not because I didn't allow it to happen It's because we plan not to run out of air.

Puffer Fish
07-30-2007, 20:51
I know on the Ocenic VT3 the DTR is not down to the minute accurate so please don't count on it. I've had it hit 0 before and still had more than enough air, plus my O2 and NDL were fine. It has only happened on a shallow dive however. Down deep when it says 5 minutes remaining you have 5 minutes.

Either way, it's bad form to let the computer plan your dive for you.
I would disagree.. kindly of course..it depends on the dive.. not a wreck dive, or a technical dive.. but a nice relaxed drift in 50 ft of water.. why not???

ChrisA
07-31-2007, 02:34
AI dose one thing wrong. It tries to compute the time remaining. It assums you will continue using air at the rate you are now. But likely you will swimm up to salower water near the end of the dive. The calculation is never right and so that feature is not so usfull. If you are buying for that reason, don't.

I don't see the problem with using just a plain old SPG and the timmer featur of my computer. I can look at the time and the amount f gas used
ad iure out about how much time I have left.

If you do dive with an AI computer you really do want a mechanical SPG
especialy of the AI system is wireless. They fail fquently The best cae of this I know of is whee this ne driver was reading his buddy' air. He had the transmitter channels crossed up some how.

ScubaToys Larry
08-02-2007, 13:22
AI dose one thing wrong. It tries to compute the time remaining. It assums you will continue using air at the rate you are now. But likely you will swimm up to salower water near the end of the dive. The calculation is never right and so that feature is not so usfull. If you are buying for that reason, don't.

I'll take a slightly different stance on that... It does compute time remaining... if all things stay constant. At that depth, it will tell how much time you have before you have to make your ascent to hit the surface with the pre-set amount of air you want as a reserve.

If conditions change, like you go shallower, deeper, start working harder, relax, etc, it will change it's calculations.

There was talk in this thread, and others on should people know their consumption rates and be able to plan their dives. Perhaps I dive a lot different than other folks - but my dives are not planned out to the minute, or the foot. Diving to me is an exploration of the ocean. If I run into a friendly turtle at 30 feet, I'm going to hang there, take pictures, etc. If I have a buddy that is having ear problems at 40 feet, we are going to make a slow ascent for a bit so he can work that out. Then when he's ok, we'll head on down.

If a pair of eagle rays swim near us, you can bet my consumption rate will go up, as now I go into high gear to try to head them off to swim near the group so everyone can get a shot.

To me that is the whole purpose of an AI computer. No matter what I change during the dive, it will recalculate on the fly for me and let me know based on what I've done up to that point, and am doing now - when I need to start an ascent.

Do you drive your car and calculate your gas mileage in the driving conditions and calculate your speed, and pick a time on your watch to fill up with gas? I don't. Forgive the pun but your mileage may vary. What if there is a traffic jam. What if you stop to get a bite to eat. I just look at either my gas gauge, and the lower it gets, the more I pay attention, or I use the little computer that tells me I have 132 miles until empty. If I step on it, that number changes. If I slow down, it changes... just like the dive computer.

People dive for different reasons, with different profiles, and with different styles, but let's not any of us on this board, or any other, say that we are "Doing it right" and the rest of the divers that don't do it like us are wrong. That is just not accurate.

I have over 5000 dives doing it "my way", and have never run out of air, or had anyone around me run out of air - because I constantly have them check, and I check. So is "my way wrong". It's just how I choose.

I believe we got different perspectives here, but let's not try to prove our points, but explain them...

Ok??

deepdiver47
08-02-2007, 19:24
It is like any other piece of equipment that you own. Once you get a sense of confidence you feel at ease with diving to your limit. (whatever that might be).

From where I sit it isn't unlike Nitrox vs Air. Once you get a feel for the benefits of Nitrox, you tend to not use air. It pays huge benefits on subsequent dives and you then become bound by air (mostly).

CompuDude
08-02-2007, 20:03
What are your diving plans for the future? If you plan to do technical diving, then you will definitely need a backup SPG. And if you need to have the SPG there anyways, what is the point? I'd go non-AI, but that is just me. If you have th emoney to spend, spend it wherever your heart desires. non AI, AI, heck spend it on (as Frank Gilbreth so well put it,) "mumblety peg, if that's where your heart lies."

Yes, I do plan on doing technical diving, which is, as a matter of fact, what got me looking for a new computer, Right now I have Suunto Mosquito. Trimix is not being considered right now, only advanced nitrox.
Personally I wouldn't dive without an SPG regardless of what computer I have, my console with a depth gauge and SPG could be welded to my first stage as far as Iím concerned.
My options right now are an AI computer and bottom timer as a back up, or two non AI computers which can also work as bottom timer if required.

That's a tough call, and really only you can answer it. AI has some very nice features. The thing is, you won't be using your computer as a computer as soon as you start going technical... you'll be using it in gauge mode, turning your fancy computer into a simple bottom timer.

If you have the AI computer, you can use it in gauge mode, plus you have the bottom timer as a backup. This is good. Not as good as two computers, from a redundancy standpoint while doing recreational dives, but you'll have two bottom times while doing technical dives. You'll only get the AI benefit (other than simple gas logging, which is not all bad) on rec dives when you use your computer as a computer.

On the other hand, having two identical computers has some real advantages, too. If you bring both, you have full redundancy... if a computer dives, you can continue your trip on the other one as if there had never been a problem. And you still have two bottom timers for tech diving when you use them in gauge mode.

For me, the ideal is an nice AI computer + a less costly non-AI computer made by the same manufacturer, for a backup. That may not be an option for you right now, however, it is something to consider for a future purchase, if you wanted to start with just the one for now.

CompuDude
08-02-2007, 20:10
I know on the Ocenic VT3 the DTR is not down to the minute accurate so please don't count on it. I've had it hit 0 before and still had more than enough air, plus my O2 and NDL were fine. It has only happened on a shallow dive however. Down deep when it says 5 minutes remaining you have 5 minutes.

Either way, it's bad form to let the computer plan your dive for you.
As you know, I agree with your last statement. However, I don't think AI computers are all bad, and as Larry pointed out, some people have some misunderstandings about how they work.

The ABT (actual bottom time [remaining]) function (referred to as RBT, remaining bottom time on Uwatec computers) allows you to set a minimum reserve, and calculates remaining bottom time to the end of the dive. The end of the dive is like when diving PADI tables: When the clock hits zero, you should have just enough gas to head directly to the surface at the proper ascent rate, do a safety stop, and bingo, hit the surface with 500 psi (or whatever the reserve was set to). This is why you still have gas even when the ABT/RBT says zero. Similarly, this is why, even as the clock counts down to lower numbers, if you ascend before getting to zero, your RBT should get accordingly longer, because the gas you have will now last you longer, in addition to adjustments to NDLs.

The function on AI computers also takes into account your present breathing rate, and this is where people get into trouble with it. In good conditions, it can actually be darn near 100% accurate. However, if you're suddenly swimming back into a current and your consumption shoots up, or you get panicked for whatever reason, or you buddy goes OOA, all of a sudden your ABT/RBT is 100% wrong, because it was calculated with assumption that suddenly changed. It will update the time remaining monetarily, but that does you little good if you have taken it to the bitter end and have no real reserve. So that time must ALWAYS be taken with a HUGE grain of salt, and used as a very general reference at best. Pre-dive planning should let you know your turn-around pressure regardless of how long your AI computer says you should have left.

So AI computers can be very handy, but they can also get a newer diver who doesn't fully understand things into trouble. Very much a double-edged sword. So ironically, they are safest to use for the more experienced divers that don't really need them.

ianr33
08-02-2007, 20:14
Does an air integrated computer include the possibility of your buddy losing all his air in its calculations? What if you are at 100 feet,10 minutes no deco time remaining and 6 minutes ATR. Plenty of time for a 30 ft/minute ascent and 3 minute safety stop. Buddies reg freeflows so you share air. Do you have enough to gas for you to both safely ascend? Are you SURE.

Personally I would not use an air integrated computer if you paid me.

thesmoothdome
08-02-2007, 20:18
Does an air integrated computer include the possibility of your buddy losing all his air in its calculations? What if you are at 100 feet,10 minutes no deco time remaining and 6 minutes ATR. Plenty of time for a 30 ft/minute ascent and 3 minute safety stop. Buddies reg freeflows so you share air. Do you have enough to gas for you to both safely ascend? Are you SURE.

Personally I would not use an air integrated computer if you paid me.

And how would having a non AI computer help you there? I fail to see the logic in what your saying.

CompuDude
08-02-2007, 20:20
Does an air integrated computer include the possibility of your buddy losing all his air in its calculations? What if you are at 100 feet,10 minutes no deco time remaining and 6 minutes ATR. Plenty of time for a 30 ft/minute ascent and 3 minute safety stop. Buddies reg freeflows so you share air. Do you have enough to gas for you to both safely ascend? Are you SURE.

Personally I would not use an air integrated computer if you paid me.
No, they do not. I'm pretty sure I said that fairly clearly in my post right above yours. "However, if you're suddenly swimming back into a current and your consumption shoots up, or you get panicked for whatever reason, or you buddy goes OOA, all of a sudden your ABT/RBT is 100% wrong, because it was calculated with assumption that suddenly changed."

ianr33
08-02-2007, 20:32
Does an air integrated computer include the possibility of your buddy losing all his air in its calculations? What if you are at 100 feet,10 minutes no deco time remaining and 6 minutes ATR. Plenty of time for a 30 ft/minute ascent and 3 minute safety stop. Buddies reg freeflows so you share air. Do you have enough to gas for you to both safely ascend? Are you SURE.

Personally I would not use an air integrated computer if you paid me.

And how would having a non AI computer help you there? I fail to see the logic in what your saying.

It wouldn't. You need to KNOW that sort of thing,not blindly trust what a computer is telling you to do.

I remember doing a dive a couple of years ago on air. Dropped down to 100 feet,looked at the computer. NDL of 27 minutes showing. HUH!!!!
Immediately before the dive I had been checking the MOD of 32% for my buddy who was diving nitrox.Because I have a pretty good feel for NDL's I knew my computer was still set to 32% (No way of checking that during a dive- Aeris Atmos Pro) Had I just followed what the computer was telling me I could have bent myself. (We had plenty of air to do that with double 80's)

I dont trust a computer to do ALL my thinking for me.

CompuDude,you are correct. Maybe I will learn to read one day :smiley36:

One of my favorite computer stories (who knows if it is true or not) is of a diver who dropped down solo to retrieve an anchor.After 10 minutes he had not returned so a buddy went to look for him. Found him at 120 feet staring at a computer that told him "STOP 5 MINUTES" which is exactly what he was doing. Except he should have been doing a 5 minute DECO stop at 10 feet!! Not racking up deco at 120 feet.

If a diver is fresh out of OW and his computer tells him he has 10 minutes air remaining I suspect most will take that as gospel

thesmoothdome
08-02-2007, 23:15
Ianr33,

No one is suggesting you follow a computer blindly. What I'm asking is why you are so dead set against an AI computer? What do they do that you consider dangerous or incorrect?

You had your computer set improperly for a 32% EAN dive when you were on a 21% mix and you're blaming AI computers for it? How would this be different with a non-AI computer? Please explain.

Statements like "Personally I would not use an air integrated computer if you paid me," just scare people trying to learn about different things without providing a real understanding of the issues.

I still don't understand how you relate your error with your dislike of AI computers. If you can explain it, I'd be most appreciative.

ianr33
08-02-2007, 23:51
Ianr33,

No one is suggesting you follow a computer blindly. What I'm asking is why you are so dead set against an AI computer? What do they do that you consider dangerous or incorrect?

You had your computer set improperly for a 32% EAN dive when you were on a 21% mix and you're blaming AI computers for it? How would this be different with a non-AI computer? Please explain.

Statements like "Personally I would not use an air integrated computer if you paid me," just scare people trying to learn about different things without providing a real understanding of the issues.

I still don't understand how you relate your error with your dislike of AI computers. If you can explain it, I'd be most appreciative.

I dont think they are dangerous as such but for me at least they are completely unnecessary. I do think that they can easily lead to complacency. As has been discussed,having an air time remaining is basically meaningless. Trust that and you might get into trouble,so why bother having it?? I cave dive when I get the chance.I turn on thirds (at most) An air integrated computer might be telling me I have another 30 minutes of dive time,but in that situation it is simply WRONG.

The primary computer for any dive should be in your head. It is interesting to me that the more experienced the diver and the more extreme the dive the less trust is placed in a dive computer.

I have done over 200 dives with my computer and I love it for what it is,but I certainly do not follow it blindly. Do a dive on air to 130 for 20 minutes and it will be telling me to stop at 10 feet.No thanks! First stop is going to be around 70 feet.

I consider integrated computers to be style over substance,marketing over reality and a huge waste of money. If your computer tells you something is OK then it must be safe ??!!

On any deep dive I do I am constantly running rough air consumption calculations in my head. Al 80,100 feet,been here 10 minutes,pressure at 2250,used 750 so thats 20 cu ft,SAC is around 0.5,looking good. I wonder how many people with an integrated computer do this?

But hey,thats just me.If it works for you then enjoy it.

No offence meant

thesmoothdome
08-03-2007, 12:05
I consider integrated computers to be style over substance,marketing over reality and a huge waste of money. If your computer tells you something is OK then it must be safe ??!!

On any deep dive I do I am constantly running rough air consumption calculations in my head. Al 80,100 feet,been here 10 minutes,pressure at 2250,used 750 so thats 20 cu ft,SAC is around 0.5,looking good. I wonder how many people with an integrated computer do this?

But hey,thats just me.If it works for you then enjoy it.

No offence meant

No offense taken. I'm just trying to understand and to be honest, I still dont. Your claim that people with AI computers follow them blindly. What I take that to mean is that people with AI computers don't follow them blindly. Forget the ATR. Are you saying that people shouldn't follow the NDL on non-AI computers? Doesn't that put us back to using tables?

I understand that you believe that AI features aren't needed. I've dove with both and and agree that they're not NEEDED. Are they nice to have? Sure. Needed? Naw. But then again, I really don't need a computer at all, but I really like diving with one.

As for running SAC calcs as you dive, I'll be honest, I don't and probably never will unless I get into tech diving. I know my SAC thanks to my useless AI computer, but I don't run numbers when I dive. I'm usually too busy enjoying my dive, keeping an eye on my gauges and my buddy. My dives are planned, like you mention with your cave diving, based on tank pressure. Shrug. To each his own.

BSea
08-03-2007, 16:43
I went through the same thing when I bought my Vytec. I kept asking "Do I need AI?" I ended up getting it because I thought there might come a time that I regretted not getting it. Plus I didn't like the Viper's compass feature. I think I posted earlier that I also use a SPG, as backup. That may change as I get more comfortable with the features.

Did I need it? No, but I have a allot of gear I don't need. At least I know I'll use this feature.

cummings66
08-03-2007, 19:00
On any deep dive I do I am constantly running rough air consumption calculations in my head. Al 80,100 feet,been here 10 minutes,pressure at 2250,used 750 so thats 20 cu ft,SAC is around 0.5,looking good. I wonder how many people with an integrated computer do this?

I wonder how many divers even bother to worry about that, forget the computer aspect even.

Now I'm a big fan of planning a dive, ask some of the divers I've upset here about knowing how to calculate how much air they need for a dive before a dive. I'm not good enough however with mental math to do all the accurate figures you just put out. I would have guessed using my immense mental abilities a .4 and been off. My method is so convoluted that I'd be embarrassed to print it out. Suffice it to say I know 750 psi X .0258 gives me 19.35 cf of gas usage/time/ata gives me the .5 you had. But that's tough.

Do you have a shortcut for the math? I do a dirty bit of math a high school teacher once taught me for estimation. I use 2 x 75 + half (.5x75) I guessed 35 to make the addition easier. That gave me 18.5 cf of usage. Then I got 1.8 / 4 ata which I just know is 100 feet which gave me the .4. At that point I know I'm using 1.6 cf per minute and know how long I can stay there based on the rock bottom value I come up with during the surface interval dive plan.

For a person as math challenged as I am, how do you make this easier? PS, I cheat on the dive plan and use a calculator to do my figures if I have to. Most of the time for the depths I'm diving I've already done them and have a laminated sheet in my drysuit box.

I feel so dirty admitting to that secret of using a calculator. I could break out the slide rule, it works under water. I forget now what my math teacher called those gross guesses, but she had a name for it and we were supposed to use this while doing things like grocery shopping so that when we got to the checkout line we'd have an idea of how much we're going to spend.

ScubaToys Larry
08-03-2007, 19:35
Well this whole conversation brings up a few points from my point of view again...

We drive a car to the airport, and look at the computer read out to determine if we have enough gas. We get into a plane to fly to a destination where the pilots use a computer to make sure they have enough gas. I'll look at my computer at depth to make sure I have enough gas.

A lot of people have popped up these scenarios of what if your consumption rate is this, your buddy does that and the current is so much when you are at some depth. You need to do these calculations in your head on the fly? When some of us are honest enough to admit to even attempt these calculations they would have to use a calculator????

So if you spend an extra 5 minutes at a shallower than planned depth because of a pair of squid you wanted to photograph, you are going to re-do all these calculations of tank sizes, atmospheres, etc...

Here's a thought. I have over 5000 dives, and never once - ever - have I been in an out of air situation with any diver near me. Perhaps that is because I spend my spare time checking on their air pressure instead of re-calculating mine. Just a thought...

cummings66
08-03-2007, 20:13
Larry,

As a pilot we don't on small planes typically use a computer to do our fuel. In fact we're taught to do it by time and not to even use the gage. The gage is certified to be accurate, when it's empty. Odd huh.

Just some trivia. My plane burns 6 gph so I know in 1.5 hours I'll use 9 gallons of fuel, I'll land and refuel and verify I burned 9 gallons.

cummings66
08-03-2007, 20:27
I should also take the time to say the only question I want answered is, can I do this dive to 100 feet for 15 minutes and be safe? If I can't, then how long can I do it for?

That's about it for what I consider important in gas planning, asides from the MODs. As a technical diver I can see where it is useful to know if you're using more gas than expected because in a cave or other restriction such as a manditory deco obligation you can't just ascend and may have to cut the dive short. Of course the SPG should tell you that pretty easy without the head math being done. That's really how I dive, I watch the SPG to verify I'm using what I should be because the math under water without my calculator is not something I would trust my LIFE to. I'm not that good.

I don't think using an AI is bad, in fact I love AI and will someday soon buy another transmittor for my other regulator. I use my brain when watching it however. I don't ever play follow the leader, that's silly.

ScubaToys Larry
08-03-2007, 20:36
Larry,

As a pilot we don't on small planes typically use a computer to do our fuel. In fact we're taught to do it by time and not to even use the gage. The gage is certified to be accurate, when it's empty. Odd huh.

Just some trivia. My plane burns 6 gph so I know in 1.5 hours I'll use 9 gallons of fuel, I'll land and refuel and verify I burned 9 gallons.

I first became a pilot about 30 years ago... my brother has a mooney and he's just finishing up his IFR rating. And true, you have those 6gph calculations - but that is based on what altitude? What throttle settings? Even if you've figured all that - if your gauge shows your low on fuel after deviating from your flight plan because you had to climb or ascend to avoid weather, speed up to miss a storm, etc, are you are going to go by your time numbers?

If you had the same technology in your small plane that you do in your car, and they do in the jumbos that calculated your fuel consumption based on your actual situation, you would blow that off in favor or your 6gph even if your flight plan was no longer the same??

Sure this can all be done in someones head if we want to turn a dive into a math class... but I'd rather take pictures of fishies...

Not that anything is wrong with folks that want to plan out all that stuff. I admire their dedication to the math and science. But I dive for fun... and somehow, I've managed to make it through all my dives without once calculating my times and depths and consumption rates in advance. Not once.

My dives are way to varied for any of that info to be of any use. We hop in for a shore dive in Grand Cayman, swim out a bit, and drop down. Head toward the wall, looking for whatever we find. Hit the wall, start back toward shore where it's getting shallower as we go. See a nurse shark sleeping... hang there and take photos. An eel is posing, hang out there. A pair of Queen Angels - watch their synchronized swimming for a bit.

For any pre-planned air / time consumption calculations, I would have to stick to planned depths and times... and I don't. I explore.

When the first person in the group hits 1500, we start heading up toward the shallower water. It doesn't matter if that is 5 or 15 minutes into the dive. About the time we hit the 40' reef area... someone may be at 750... we'll work our way up the coral, or ascend to a nice safety stop depth, then surface, swim on our back the rest of the way to shore talking about the stuff we saw. To me... that is diving.

Before the first dive is over with a group, I'll tell you how much air everyone I'm leading has - as about the only calculations I do is know that this girl is using about the same as me, this guy is using 300 to my 200 etc. I just make sure no one gets low - and we explore what the ocean serves up! And I do it with an air integrated computer.

Just because a computer is air integrated, does not mean I can't look at the pressure reading if I want to try to do that math that it does easily.

You said you use a calculator to determine times and depths?? Why do you trust that computer chip in a device that costs $1.95 and not the one in a $700 dive computer?

awap
08-03-2007, 20:47
It is just a matter of time before someone comes along with a dive computer that will take your dive plan as input and then be able to provide some potentially useful output that can really be used to manage your dive - so you can concentrate on pictures. I'm pretty sure the price will be outragous so I probably will not be getting one. Until then, I see bells and whistles with little utility unless you just can't estimate your SAC without one.

It's not a matter of trust. I'm happy with my $68 used Data + (I'm getting pretty good at depth in meters, forget temp) and I'm going to use the change for a couple of FGB trips.

ScubaToys Larry
08-03-2007, 20:52
awap... you're telling me that you can account for varying conditions - like now there is a current, and the best place to swim against it is at 48 feet, and you have 1500 psi, you can tell me how many minutes until you get to 750 psi... and calculate that based on how your are working in that current, and pop that answer out in a few seconds while concentrating on your buddy? No way I can... but my AI can.

Again guys, I'm not saying doing it "long hand" is wrong. It's just too much work for me! My hats off to people that can do that on the fly knowing exactly what their SAC rate is under varying conditions and varying depths.

But I don't balance my check book by hand either... I use quicken.

awap
08-03-2007, 21:17
awap... you're telling me that you can account for varying conditions - like now there is a current, and the best place to swim against it is at 48 feet, and you have 1500 psi, you can tell me how many minutes until you get to 750 psi... and calculate that based on how your are working in that current, and pop that answer out in a few seconds while concentrating on your buddy? No way I can... but my AI can.

Again guys, I'm not saying doing it "long hand" is wrong. It's just too much work for me! My hats off to people that can do that on the fly knowing exactly what their SAC rate is under varying conditions and varying depths.

But I don't balance my check book by hand either... I use quicken.

Heck no. But I'm saying I can plan my dive based on available gas, estimated consumption rate, depth, and time. And then I can manage that dive based on time and gas consumption, planned vs actual; and adjust it as necessary due to higher or lower gas usage (effected by conditions). I almost always end up at the rest stop with more gas than planned. Oh well, extended rest stops are OK too.

And if you are doing that with your AI computer then you are probably planning based on ATR/DTR. And that's great. You may want to teach others how to do it.

I was wonderfing how that AI computer adjusts for current conditions (changes in sac) that you may encounter during the ATR/DTR that it forcasts. Actually, I wasn't. I know it can't. But I can. It's not very accurate but it just another condition, including conditions I know lie ahead, that I can adjust for.

My wife takes care of the checkbook. I make too many guesses. That way, I never run out of $$$.

thesmoothdome
08-03-2007, 21:37
So you're going to trust your mental calculations more than a computer that's designed to crunch all the numbers you're trying to do in your head?

Like Larry, I've never used my SAC rate to plan dives. Yet, unbelievably, I've never run out of air or been bent (knock on wood) or had a buddy who has. An AI computer just gives you more information. You still have to make the calls.

So far, all the AI bashers claim is that AI isn't good because it fosters a dependency on a computer. Most of the rec. diving community dives computers and trust them to do the calculations for us. Is that dependecy? Does it really matter if the computer is AI or not? Come on guys, give up the tired argument. Give me good reasons why you dislike AI computers. "It gives too much information" isn't really a good reason. I can understand if you don't think they're worth the money. Just say that. Stop trying to hide under the fallicy that if you can't calculate your SAC rate, you aren't a diver.

ScubaToys Larry
08-03-2007, 21:44
My wife takes care of the checkbook. I make too many guesses. That way, I never run out of $$$.

If you have checks - you have money. Right?

As far as the diving stuff... The way you dive is great. Most people don't have that good of a handle on how their consumptions will vary based on constantly changing conditions. You obviously are very aware of your conditions and know your stuff.

Seriously... and please don't think bad of me... I really don't plan much. I jump in... we pick a direction based on conditions - we go. We punch in a turn around pressure into the (yes) ai computer and when it beeps - we turn back. We change constantly depth, conditions, etc. At any given point, I can look at my wrist (or soon - inside my HUD mask!!!!) and I know how much gas I have, and if I stay at this depth and work load, how much time I have before I need to start an ascent in order to hit the surface with my pre-determined surfacing pressure. It tells me if I will run out of air time or nitrogen time first. A push of a button gives me the other info. I can devote all my facilities toward photos, exploring, or concentrating on my buddy. For my type of diving - that's nirvana.

thesmoothdome
08-03-2007, 21:52
I was wonderfing how that AI computer adjusts for current conditions (changes in sac) that you may encounter during the ATR/DTR that it forcasts. Actually, I wasn't. I know it can't. But I can. It's not very accurate but it just another condition, including conditions I know lie ahead, that I can adjust for.
.

My computer recalculates my SAC every 30-60 seconds. The manual states: "The change in your air consumption will be based on constant one second interval pressure measurements over 30-60 second periods. An increase in air consumption will influence the remaining air time rapidly, while a drop in air consumption will increase air time slowly. Thus a too optimistic air time estimation, caused by a temporary drop in air consumption, is avoided."

Of course, it can't forsee upcoming conditions, but it does change very often and can do the math much faster than I possibly could.

awap
08-03-2007, 22:15
I was wonderfing how that AI computer adjusts for current conditions (changes in sac) that you may encounter during the ATR/DTR that it forcasts. Actually, I wasn't. I know it can't. But I can. It's not very accurate but it just another condition, including conditions I know lie ahead, that I can adjust for.
.

My computer recalculates my SAC every 30-60 seconds. The manual states: "The change in your air consumption will be based on constant one second interval pressure measurements over 30-60 second periods. An increase in air consumption will influence the remaining air time rapidly, while a drop in air consumption will increase air time slowly. Thus a too optimistic air time estimation, caused by a temporary drop in air consumption, is avoided."

Of course, it can't forsee upcoming conditions, but it does change very often and can do the math much faster than I possibly could.

It is a benchmark or reference point so long as you understand its limitation. You clearly understand what it is doing. Unfortunatelyu many don't. Depth and currents are two variables that can usually be forcasted. With currents, I try to control my level of effort so my sac is not effected too much. But I do allow twice as much time to cover a distance into the current as opposed to with it. And if the current is anything more than mild, I'll always start off into it so if my 2:1 allowance is wrong, it will leave me with more gas than planned, not less.

I'm not hung up over any computer dependencies. Heck, there are some folks who believe anything other that a bottom timer will rot the brain. As you can probably tell, I'm just cheap. But, in your case, it's not like you had to give up a fabulous dive trip so you could have that AI computer. So enjoy them both.

ertechsg
08-03-2007, 22:23
Seriously... and please don't think bad of me... I really don't plan much. I jump in... we pick a direction based on conditions - we go. We punch in a turn around pressure into the (yes) ai computer and when it beeps - we turn back. We change constantly depth, conditions, etc. At any given point, I can look at my wrist (or soon - inside my HUD mask!!!!) and I know how much gas I have, and if I stay at this depth and work load, how much time I have before I need to start an ascent in order to hit the surface with my pre-determined surfacing pressure. It tells me if I will run out of air time or nitrogen time first. A push of a button gives me the other info. I can devote all my facilities toward photos, exploring, or concentrating on my buddy. For my type of diving - that's nirvana.

Thanks Larry for a while I was thinking I was the only one who dived with out that much planning. It's not like I'm diving the Doria

ianr33
08-03-2007, 22:30
Give me good reasons why you dislike AI computers. "It gives too much information" isn't really a good reason. I can understand if you don't think they're worth the money. Just say that. Stop trying to hide under the fallicy that if you can't calculate your SAC rate, you aren't a diver.

Well,as you asked :smiley36:

Not worth the money. Better spent on going diving

If it is on the end of the High Pressure Hose it has to stay there. If you decide later on in your diving career that it would be better on your wrist then you need to buy a new computer. (unless maybe you can take it off the hose and plug the hole?)

If it is wireless then most divers will still use an analog spg as well.The transmitter is yet more $$$ and is an extra failure point (Although thats probably not going to kill you! )

I think that for single tank recreational dives they are probably fine !!!!!!!(O.K. I admit it !!!!!)
But for more complex dives they just dont cut it. What if you are carrying a stage? Can it read the gas in that? What about valve drills? Will it reastablish communication underwater after the pressure goes to zero (I understand some models will not) What if you are scootering? The VT3 manual warns that a scooter motor will mess up the wireless signal

I have a simple hockey puck nitrox computer that I bought maybe 10 years ago.Its original home was a console,now it sits on my wrist.It is with me on Trimix dives (although it gets bent rather easily!) and cave dives.
Had I bought an air integrated computer I would have Ebayed it years ago

awap
08-03-2007, 22:42
[quote=ScubaToys Larry;16440
Seriously... and please don't think bad of me... I really don't plan much. I jump in... we pick a direction based on conditions - we go. We punch in a turn around pressure into the (yes) ai computer and when it beeps - we turn back. We change constantly depth, conditions, etc. At any given point, I can look at my wrist (or soon - inside my HUD mask!!!!) and I know how much gas I have, and if I stay at this depth and work load, how much time I have before I need to start an ascent in order to hit the surface with my pre-determined surfacing pressure. It tells me if I will run out of air time or nitrogen time first. A push of a button gives me the other info. I can devote all my facilities toward photos, exploring, or concentrating on my buddy. For my type of diving - that's nirvana.
Thanks Larry for a while I was thinking I was the only one who dived with out that much planning. It's not like I'm diving the Doria[/QUOTE]

How do you know what turn around pressure to input?

ScubaToys Larry
08-03-2007, 22:53
How do you know what turn around pressure to input?

Ummm... I take 3000.. Plan on hitting the surface with 500, so I just drop in 1750. I know that is half my time if I was at equal depths throughout... but normally hit the deepest part first, so that gives me a bit of extra time for the second half as I'll be shallower. Probably logged my last 2000 dives doing this method. Back when it was a 750GT computer. Never ran out of air yet! But there's always the next dive!

CompuDude
08-04-2007, 00:22
My wife takes care of the checkbook. I make too many guesses. That way, I never run out of $$$.

If you have checks - you have money. Right?

As far as the diving stuff... The way you dive is great. Most people don't have that good of a handle on how their consumptions will vary based on constantly changing conditions. You obviously are very aware of your conditions and know your stuff.

Seriously... and please don't think bad of me... I really don't plan much. I jump in... we pick a direction based on conditions - we go. We punch in a turn around pressure into the (yes) ai computer and when it beeps - we turn back. We change constantly depth, conditions, etc. At any given point, I can look at my wrist (or soon - inside my HUD mask!!!!) and I know how much gas I have, and if I stay at this depth and work load, how much time I have before I need to start an ascent in order to hit the surface with my pre-determined surfacing pressure. It tells me if I will run out of air time or nitrogen time first. A push of a button gives me the other info. I can devote all my facilities toward photos, exploring, or concentrating on my buddy. For my type of diving - that's nirvana.
And you know what? There's absolutely nothing wrong with that.

The difference, however, between what you and what a new diver does is that you consciously make choices in the back of your mind based on years of experience... your subconscience actually governs the decision. Making decisions by the seat of your pants is all well and good for people with enough dives that an "educated guess" actually has some knowledge behind it. The problem comes when you either don't have the experience to know what goes into such a guess, or when you try to make an educated guess and fly by the seat of your pants for a complex dive.

That's not the case with your diving... you're not doing wreck penetrations and incurring deco time. You're not diving in overhead environments. I think a lot of very highly educated, very skilled divers forget that while the slightest mistake deep in a wreck, cave, or at 300' can and probably will kill you, slightly miscalculating by a few minutes on an easy reef dive is highly unlikely to (depending on the miscalculation, of course).

The only way to be completely safe is to never enter the water. Anything beyond that is determining what level of danger you are comfortable with. The difference between an experienced diver and a new diver making those decisions, however... that's what makes all the difference.

I have done many SAC and rock bottom calculations. However, for the majority of the diving I do, it's simply not necessary. For the dives where it IS necessary, you bet your sweet bippy I'll be getting out the calculator and software. But for my 30th dive at a given location, even if I'm going down to 100' or so, I have enough of an idea of what's safe and what's not, based on experience, that it's far safer for someone like me (or someone like you, or someone like thesmoothdome) to have an AI computer. That experience lets us say "wow, that number is way off" and "well, forget that, I'm going to be headed into the current on the way back to the boat, so I'd better start back now".

Any other objections based on price are absurd, because every individual's tolerance and sensitivity to a given price point is going to be drastically different. A millionaire doesn't give a rats *** that an AI computer costs a lousy $300 more than a non-AI one... the AI one is cooler, and while he may or may not need every feature it offers, he is well within his rights to want it... and since it's within his means, who out there has the right to condemn him for it? And you don't have to be a millionaire for that to apply... someone making $80k per year could very well have enough disposable income that buying the AI computer today means waiting another month to pick up the iPhone, and that's ok, too. For someone making $25k per year, the sacrifices needed to spend that extra $300 for features that aren't necessary becomes way out of whack. But again... for goodness sake, people, stop ASSuming what is and is not "too expensive" because frankly, you have NO IDEA whether it truly is or not.

CompuDude
08-04-2007, 00:27
Give me good reasons why you dislike AI computers. "It gives too much information" isn't really a good reason. I can understand if you don't think they're worth the money. Just say that. Stop trying to hide under the fallicy that if you can't calculate your SAC rate, you aren't a diver.

Well,as you asked :smiley36:

Not worth the money. Better spent on going diving

If it is on the end of the High Pressure Hose it has to stay there. If you decide later on in your diving career that it would be better on your wrist then you need to buy a new computer. (unless maybe you can take it off the hose and plug the hole?)

If it is wireless then most divers will still use an analog spg as well.The transmitter is yet more $$$ and is an extra failure point (Although thats probably not going to kill you! )

I think that for single tank recreational dives they are probably fine !!!!!!!(O.K. I admit it !!!!!)
But for more complex dives they just dont cut it. What if you are carrying a stage? Can it read the gas in that? What about valve drills? Will it reastablish communication underwater after the pressure goes to zero (I understand some models will not) What if you are scootering? The VT3 manual warns that a scooter motor will mess up the wireless signal

I have a simple hockey puck nitrox computer that I bought maybe 10 years ago.Its original home was a console,now it sits on my wrist.It is with me on Trimix dives (although it gets bent rather easily!) and cave dives.
Had I bought an air integrated computer I would have Ebayed it years ago
For complex dives, they generally don't cut the mustard. (there, I said it too!) Oh, wait... They can still be used in gauge mode, right? So I guess they're not totally useless?

And mine, for one, can handle up to three transmitters, so actually, yeah, I can handle that switch to another stage, and later, to 50 or 100% o2 during deco. More than that? Gee, I guess I'll have to depend on the analog gauge (since, as a prudent diver on a complex dive, I would never have ONLY wireless giving me info) just like everyone else, and my computer won't be telling me how long I can stay down anymore! Oops, that's right, I'm in gauge mode. I guess it's not telling me that after all. It's merely recording my dive for later analysis while I dive my plan, dutifully written in my wetnotes.

So what's wrong with that?

Or is this about money again? If so, see my previous post.

TxHockeyGuy
08-04-2007, 00:54
How do you know what turn around pressure to input?

Ummm... I take 3000.. Plan on hitting the surface with 500, so I just drop in 1750. I know that is half my time if I was at equal depths throughout... but normally hit the deepest part first, so that gives me a bit of extra time for the second half as I'll be shallower. Probably logged my last 2000 dives doing this method. Back when it was a 750GT computer. Never ran out of air yet! But there's always the next dive!

This is exactly how I dive and generally it works out well. Often I have to overshoot back to the dock (usually I'm not diving blue water on a boat) which lets me run our tanks down to closer to 500. On very rare occasion I have to surface before getting back to the dock which means a slightly longer surface swim but still a safe dive.

Zenagirl
08-05-2007, 07:32
I agree with Larry on this one. I'm a recreational diver who wants to explore and enjoy the ocean, not do complex technical dives. I like my AI computer since I have all of my information in one place....I can even navigate with my compass with my computer screen visible the entire time. When the time comes for me to get a new computer, I'll stick with AI but go hoseless. :D

awap
08-05-2007, 09:28
It sure shouildn't hurt to have an alarm go off at the halfway point but there are time when that just isn't enough. It works fine if you want to drop in, follow a course out for half the dive, then follow it (or shallower) back for the 2nd half. But there are a lot more recreational dives where that just isn't enough. The Flower Gardens is a good example. Most of those dives will run 80 to 100 ft max with a shallowest bottom at 65 to 75 ft. If you are diving air, you will probably be NDL limited. But if you are diving Nitrox you will probably be gas limited. So, first question should be how much bottom time do you have to work with? And to work that, you will want to decide how much gas you want to end up with. My default plan with an S80 is to arrive at the rest stop with 500 psi/13 cu ft (perhaps a bit low but I carry a yellow buddy if the fit hits the shan). Backing up from there, I plan to start the ascent at 750 psi which allows about 5 minutes including a couple minutes at 30 ft. And finally, to make all that happen, my plan is to have the mooring line in sight by 1000psi. So that leaves 2000 psi or 56 cu ft to play with. Depending on depth and with a .5 sac, that is at least 30 and more like 40 minutes to explore. Depending on the site and conditions, that may be a compass heading out 400 to 600 ft (east bank # 1, 1st dive of the day) and a similar course back with a turn at ~2000 psi. Or it may be a number of wagon wheel spoke type shots going out 2 to 5 minutes, run a short arc, and back in sight of the mooring line. Currents will have a lot of effect on those segments. But the point is a single mid-point alarm is not very useful or necessary. My simple computer is on my wrist and I can tell pretty much how much gas I've gone thru by how much time has elapsed. I check depth, time, and direction a lot more frequently than my SPG which is clipped off on my left side.

Even for local lake dives, I don't find the midpoint on gas to be very important. We had located an old U/W pump station in about 40 ft but the route that I knew to get there involved a couple navigation legs and about 900 ft. So it took about 10 minutes and almost 500 psi to get there to spend 25 to 30 minutes exploring and head it back around 1000psi (again with S80s). One time we took a new diver (air hog) with us so we had to redo our gas plan. I slung an S63 which I used for the 1st 2 U/W legs with my buddy and his new diver son following the flag on the surface. They then submerged and we put the new diver on my long hose while I stayed on the slung tank until we got to the pump station. Then we all went to our own gas and spent about 25 minutes exploring before the new diver was down to about 1200 psi and we headed directly toward the shore. BTW, we now have it mapped out so we can go directly from shore to the U/W site but it is a featureless 600 ft shot that does not leave a lot of room for error.

Not all recreational dive are simple out & backs. Sometimes you may want to plan the dive a bit more thoroughly and think about what alarm setting is most appropriate.

ScubaToys Larry
08-05-2007, 10:06
Then if that is the case... Just change the gas and or time alarm on what you plan. Set the gas alarm to 1000 or 1500 or 2000. Set it to beep when you are down to 10 minutes of air at any give depth. Set it to beep if you get within 5 minutes of your NDL. You pick! Or turn off all the alarms and just do it the old fashion way.

Is air integrated necessary?? Of course not. But neither is a cruise control in a car, a spell check on a word processor or the ability to get emails on your phone. Heck - a dive computer isn't necessary. You can do tables. But if you like technology, and want to use some of the benefits of it, it can be a very valuable tool if you learn how, and choose to use it.

In the scheme of things, when I have someone that is taking a scuba class, buying a full set up of gear, and heading to Cozumel for their first dive vacation, they are probably spending $3000 on class, trip and gear. Whether they spend 2750 or 3000 may not matter to them. And if they can afford the extra money, and want the benefits - I'd tell them to get it.

But I outfit divers every day with a simple reg and gauge setup - or maybe just a base wrist mount computer. It's all just options. Neither is right or wrong.

ianr33
08-05-2007, 10:11
Considering the cost difference between an AI vs., a non-AI computer, I'm debating were the advantages the AI computer provides are really worth it.
For example I can purchase two Nitek duo computers for the price of a single VT3 with one transmitter, which are the front runners on my list of options so far.
So I can have my main and back-up non-AI computers for the price of a single AI one.
Which way would you go, and why?

Get the 2 Duos (Or better get 2 Tusa IQ-700. Same computer,longer warranty)

The Duos will work for ANY diving you will ever do (although they may be in gauge mode one day)

awap
08-05-2007, 10:44
Is air integrated necessary?? Of course not. But neither is a cruise control in a car, a spell check on a word processor or the ability to get emails on your phone. .

You can get e-mail on your phone???? I'm still trying to figure out how to work my camera.

ianr33
08-05-2007, 10:54
Is air integrated necessary?? Of course not. But neither is a cruise control in a car, a spell check on a word processor or the ability to get emails on your phone. .

You can get e-mail on your phone???? I'm still trying to figure out how to work my camera.

I'm still trying to figure out how to program my VCR. How DO you stop the clock flashing?

awap
08-05-2007, 10:56
Is air integrated necessary?? Of course not. But neither is a cruise control in a car, a spell check on a word processor or the ability to get emails on your phone. .

You can get e-mail on your phone???? I'm still trying to figure out how to work my camera.

I'm still trying to figure out how to program my VCR. How DO you stop the clock flashing?


Unplug it.

ScubaToys Larry
08-05-2007, 12:00
Is air integrated necessary?? Of course not. But neither is a cruise control in a car, a spell check on a word processor or the ability to get emails on your phone. .

You can get e-mail on your phone???? I'm still trying to figure out how to work my camera.

I'm still trying to figure out how to program my VCR. How DO you stop the clock flashing?

Black electrical tape.

cummings66
08-06-2007, 08:57
You said you use a calculator to determine times and depths?? Why do you trust that computer chip in a device that costs $1.95 and not the one in a $700 dive computer?

I just got back from diving so this response is dated. However I want to address a few things.

First the way you said you do your dives is pretty much the way I do mine, I watch the pressure and start back at a determined level, go to a shallower depth and dive there until I hit a level, so on and so forth.

The math I do is just a surface exercise to see if we can do the dive we want to, part of the dive plan. Once we submerge no more math.

On small airplanes even those electronic gauges are not exactly accurate because they're not like our cars gas gauge. They work by you inputting the amount of fuel in the plane to start with, if the gas guy gives you less fuel and you say it's full the electronic gauge will report back incorrect data, garbage in = garbage out. I've got a buddy who installed one in his C150/150. It's fine as long as you know the starting levels, but it's actually an electronic guess. That's why small plane pilots tend to do math more than not. If I had a reliable gas gauge I'd use it instead.

On to diving, math and AI computers. I do use my pressure from the computer, I watch it and trust it. In fact this weekend I was diving and playing with that very aspect of it a lot. I got 3 hours worth of bottom time in and used the AI part to judge it all. As I suspected it's pretty accurate, on the VT3 and it's clone if you breathe harder it tells you you have less time, if you go easy you get more time. I could increase or decrease my time as much as 10 minutes at 100 feet by how I breathed.

I also did the gas switch with it to further test things and it did that without a hiccup. The time remaining was correct for the depth and amount of air in the tank.

As far as I can tell at least the VT3 is correct when it concerns air pressure and how much time you have left until you hit your turn pressure, you can trust it. I actually do.

My dive planning on a deep dive which I consider 100 feet to be is one where I use math to figure out how much air I'll need for the dive being considered. Math as we do has many fudge factors built into it and to be honest is more conservative than the computer because it's right on the gnat's xxx. When you do math you're essentially making an educated guess and you pad it to be safe.

However I do not do any math under water because I am not capable of doing it in real time, I need a calculator to do real time and I don't see that it's of any value under water.

To show you how much I trust it for recreational diving right now, I do not carry my SPG. I've ditched it totally in favor of the AI. I've been diving with the AI computer for a year now or close to it and it has not once lied to me, lost lock, it's never even glitched for a bit. I trust it due to a years worth of diving on it. My backup plan in a failure is to head up because I'll know how much air I have and how much I'd use based on experience and it's not an issue for me.

If I was doing a technical dive I'd have an analog SPG to back it up with. I see nothing wrong with using AI and being able to trust it. For the most part it gauges real time my gas usage better than I can under water. That's because I can't do math real time, it takes me a couple minutes to guesstimate things. In that time things have changed and my answer now isn't valid.

cummings66
08-06-2007, 09:22
Right now, I have my VT3 set to 400 psi in the tank for the target, no turn pressure. I watch my gauge and decide that based on experience. In fact I rarely do math anymore because for the most part I already know how much air I should have when I turn and use those values.

I watch my computer, the pressure is mainly what I watch, ATR or DTR is a value I watch to see what it says for fun. It is accurate and does account for your SAC going up and down so swim as hard as you want, it'll show you that you have less time under water now. It's pretty neat. Like I said, I did a lot of playing with those numbers this weekend just to see how useful it is. It is better than I am when it comes to math. I told it I wanted 400 psi in my tank, I had 453 psi when I came up. I could have made it exactly 400 if I wanted but by using my brain along with it I could stay at any depth I wanted as long as I played the numbers out.

I will tell you I know roughly how many cf of air I need for the dive, but the computer will tell you without you knowing when it's time to come up. I have proved that many times over. I still dive within my plan but the computer is right when it concerns air pressure and allows me more flexibility without under water math.

tywenglar
08-08-2007, 13:54
I have the Aeris AI. It does not have a transmitter as it is hose mounted. I absolutely love it. I'm a bit of an air hog so most of my dives are governed by air consumption rather than nitrogen loading so it is nice to know how much time I have without having to just guess at it. The hose mounted is cheaper than the transmitter versions.

BTW, Beacasue the AI has all your info in one spot (depth, pressure, loading) which is nice but if it ever fails I'd be SOL. So....I wear an Oceanic Veo on my wrsit as a backup. Oceanic and Aeris use the same algorithm so they read the same on loading and the Veo is cheaper.

creggur
08-08-2007, 15:53
a spell check on a word processor

I beg to differ here.... I need a spell check any time I'm in front of a computer.... Just downloaded the one for the forum, so I don't look like such a doofus..