Do I really need a computer?

[sff]

Let me post one other reason as to why I prefer dive computers to using tables. That has to do with dive planning.

A little heresy here. And I do not advocate that novice or even less experienced divers do what I do. They absolutely should dive the way they were taught. I am just explaining how I dive and how I use a computer to support that method. I've been diving for years and have excellent buoyancy control and air consumption. As I gained experience my diving changed.

I don't plan dives in advance. Not really. I know what I can dive and I know what my profiles are, so I don't make plans in advance. But that doesn't mean that I don't pay attention to what I am doing at all times. In fact, I would argue that what I do is constantly plan the rest of my dive while I am diving. And for that matter, when I am doing repetitive dives, I treat the entire situation as one long dive, in which I spend a certain amount of time at 0 fsw.

The problem with tables is that they only give you a snapshot and then it is just an approximation of what you have done. They don't give you continuous, up to the moment, real time, information that is completely specific to you and your current profile. A computer gives me this information, so that at any moment in time, I can make decisions as to what I want to do next.

How does this work. Let's say that I am making my first dive and I am dropping on a pinnacle that starts at 70 feet. I don't have any plan for what I am going to do. Now I do have some rules I follow, such as I make my deepest dive the first dive of the day, I also want to be no more than 25 feet down with less than 700 psi, and I will always make a 5-10 minute safety stop at around 20 feet, and I don't go below 140 feet without some reason.

As I am diving, I constantly keep track of my air consumption, my psi, and my nitrogen uptake (and O2 if I am diving nitrox). And I make my decisions as to what I do next based on those issues. And I am thinking ahead, trying to keep a little bit of leeway in case of emergencies. So when it is time for me to start slowly coming up, I start coming up. Such as moving up from 80 feet to 60 feet. The computer gives me the information I need to make those decisions.

During the surface interval, I don't plan the next dive. I want to know where I am diving and will take that information into consideration. And I have a pretty good idea of how long I need to stay out between dives. I can get an idea of that from the computer. And occasionally I will look at the computer to see what my current NDL are for various depths as a gauge to how long I need to stay out. But that is about it. Or conversely, I am doing the same kind of planning at the surface that I do underwater, but with a different set of information.

It is only when I am underwater for the next dive, that I start planning how long I am going to stay at a particular depth before moving up. But this is something I do on the fly based on the situation and what is happening under water.

One caveat, if I were diving for a very specific reason (to go down and work on something), then I would plan my dive. But my dives are freeflowing. And the computer allows me to dive that way. Something I could never do when I was using tables.

My two cents,

Steve

 

[LavaSurfer]

A) Is it to allow more bottom time? B) Do we use it to keep use 'safe', preventing DCI on our dive? C) Tell us how many munites of air we have left? D) Tell use how much deco time we have? E) Tell us our turn pressure based on tank size? Will it allow one to enter tank size? F) Keep track of all divers in the dive team?

I think you bring up important and accurate questions but in fact they are statements I use my computer because I wamt to most time under water I can get wthout exceeding NDL. Computers do a fairly good job at this and if you use a conservitive computer they are safe. Sure you could use a wheel and calculate multilevel dives, AND I DO, but underwater the plan is based on tables and monitored via the computer. I find them close. Also, I monitor not only my air annd my wifes air. Its kind of cool and if she gets too far from me I get a signal loss alert and we buddy up again. I like us close in case of emergency because we typically dive around 80 -110 FSW. then move up to 60 FSW and ten 40 FSW to compete the dives. We both keep track of our time, Computer readings and always react to the most conservitive readings. Also, I like the fact that they track ascent rates and alarm, monitor SAC and time Safety Stops or me. Not that a computer is needed for any of these but they do a good job. Last but not least, they are great educational tools when you use the data in software like scubase to evaluate plan vs actual after the dive. Having a computer is a luxury to a rec diver in my thinking. Tec divers on the other hand need such complex plans that tere is really no computer that can monitor all the stops, changes and timings. If I were doing serious tec diving I would use something like waterproof printouts from vplanner, a VR3 DC and a good lap stopwatch. along with a buddy double checking every move.

 

[boomx5]

One caveat, if I were diving for a very specific reason (to go down and work on something), then I would plan my dive. But my dives are freeflowing. And the computer allows me to dive that way. Something I could never do when I was using tables.

My two cents,

Steve

We do it the same way most of the time except we don't use tables or a computer. I mean, there are some minor planning issues that come into play as far as rockbottom direction, distance, scooter burn time etc, but most of these are adjusted on the fly if you know how to do it. I guess it's just a matter of personal preference and what one is comfortable with.

 

[ishbaby]

Im just new to diving, and I got dive buddies and a dive master that got computers, so when I dive, I just rely on them. I would probably need one soon once I understand the technicalities of diving REALLY well. Dive computers can be really expensive, and prior to buying, I have to fiddle around with their computers first hehe.

 

[Sordello]

I agree an internal combustion engine doesn't inherently need a computer but I believe some newer models that use computers to control injection of fuel do.

Most subsonic jet aircraft do not require a computer to operate but it is so integrated that "dead stick" wouldn't be a welcome proposition either. No pwer, heavy and far from home. Some military models that fly over your homes are built to be aerodynamically unstable - no computer, no control of pitch, yaw and roll. You couldn't glide far with the stubby wings anyway.

I agree that having a computer shouldn't turn off the brain. I think you should know your tables and how to operate your computer. If it tells me I'm clear to go to 130ft on EAN 40, I know that I have input something wrong or it has a major malfunction. I usually carry a backup so my first thought would be to check it. Should I not be carrying it, there should be a buddy close at hand to check theirs. If all three disagree with my brain, I'm not thinking clearly and it's time to end the dive anyway. I treat my computer the same way a pilot treats his instruments. If the brain and the instruments are in conflict you must stop, think about the situation and determine which to trust. For pilots it is the decision between potential gauge failure and potential vertigo.

That statement puts the use of a computer gear down as clearly as it can be put. First and formost trust your brain. I started this thread to help me decide if buying a computer was worth the investment. I am a gadget person and a computer geek. I love fine toys, but my new joy is traveling. Simple rule number 1 - carry half as much stuff and twice as much money. The question of "Do I need a computer" was based on that concept. I quickly realized it was a dumb question because all I wanted was a dive logger.
This would make my work a lot easier and very convienent. I ended up buying a Sensus Pro Dive logging device. The GVI organization which advertises on this website does not allow the use of computers to plan a dive or to execute unplanned dives. They also do not allow a computer to be used as a primary guage. All dives are preplanned using a PADI RDP - This is the most significant factor that made my final descision about buying a computer.
It allows me to spend a bit more money on underwater a underwater digital video recorder - cool huh! I'll enjoy it - I hope it holds up in sothern Mexico - if not I'll still have a great time - "working"
On another concept you can't equate flying an airliner with diving on any level I can imagine. You have no sense of speed or deceleration while flying without instruments. At the least you can watch bubbles while under water and determine which way is up. I hope that the simple rule of going up at a slower rate than the bubbles hasn't changed over the last few few years.

 

[boogeywoogey]

I would get a computer if I were you. Also, take tables with you and if you have the discipline, take time to do some calcs at depth on your slate and run through scenarios.

You are diving at 33ft now, if I remember correctly, but likely to be diving beyond that soon. Computers are a must these days for some of the reasons quoted above but always be able to have access and be able to use tables when you're down in the dark.

I always dive with 2 comps and tables. I laminate tables for different mixes (ccr and trimix and bail out/deco gases) but always 2 comps.....I suggest you get a comp, they're fairly cheap these days anyway and it's something to focus on when you get the wobbles.

boogey

 

[devolution365]

First, about the Microsoft Excel debate: check out www.openoffice.org Its a software package EXACTLY like Microsoft Office, but it's FREE. Completely compatible... I use it at home and at work and I love it!!!

Now, back to computers...

I've been debating the computer issue as well. It's not that I want longer bottom time (my buddy usually runs out of air before we're anywhere close to the table limits), but more because I'd like to know the water temperature and depth at a glance. I've researched and found that buying new is expensive. You can, however, get a simple (no nitrox) used computer for around $100 on eBay. Then I got to thinking... A thermometer is cheap. A depth guage is included in my rental gear (I only own mask, snorkle, fins). I'm not currently planning my dives (I'm diving with a charter), and making myself pull the guage out of my bcd pocket to see my depth is also a good reminder to check my air.

Conclusion: I don't need a computer. (This summer I will be planning a few dives, but I'd rather stay ultra-conservative and stick with the chart when I do that since I'm still very much a newbie.)

Now, for the geek factor (me and my SO are geeks by trade), I may just pick up a Sensus Pro/Ultra. I think having all the info after the dive would be nice.

 

[duckbill]

It's comforting to know that tables vs. computers is still being debated. I was beginning to think that NO ONE knew what a table was anymore. When I pull my tables out at a dive site, more often than not the divers around me have this dumbfounded look on their faces as though I had just pulled out a sliderule or something!

 

[PerroneFord]

Well, I know what a slide rule is, but I wouldn't use one! LOL I wonder what looks I am going to get this weekend when I show up with a depth guage and not a computer!

 

[Kevin K]

Got 6 whole dives under my belt and the last 2-which were the first 2 on my own...were with a computer-air integrated. What an awesome piece of gear!!! Starts computing on it's own,gives me depth,pressure left in tank, how long that air will last at my breathing rate, NDL constantly updated, count down when I got to 15 feet, counts my surface interval and then starts all over again for my second dive!!!!!!!!!! Taking into account all of the info from the first dive including SI. Of course, during my surface interval I consulted my RDP, everyone else on the boat was amused but I did what I was taught and it felt good. Can't wait till I learn how to use all of the functions! But I want to be a good diver so I will always have my RDP with me-just in case. Suunto Vyper was what I was using. What a rookie, huh???