Do I really need a computer?

[Rick Inman]

I've gotten to the point where I have memorized a lot of the bottom times at different depths.

I don't think you should memorize the table.

I don't think there's anything wrong with it.

The micro processor has come a long, long way. But it is still infinitely far from being able to equal the human brain. Which is why, if during a dive I have a "feeling" that I should stay a few more minutes at the last stop before surfacing, I do. Because I trust that it can be the amazing human brain putting things together that no computer can. It knows everything - my age, how I'm feeling, how hydrated I am... It actually knows how much n2 is in my tissues, without doing a Doppler test.

Here's some information for historical value only : Some divers have been known to average their depth in their brain (they say it becomes easy with practice), then add their bottom time to there average depth, and use a total of 120 as their NDL. They often change their exit strategy from, "head straight up to 15' for 3 mins", to stopping at 10' intervals for a minute on the way up, and then spending a long time moving up the final feet. No computer, long bottom times and they come out nice and clean.

 

[DA Aquamaster]

On the other hand, who is to say someone who overstays their times and requires mandatory deco, but doesn't do it right and gets a hit doesn't sue the agency for failing to put that info on the table? This is one of those areas that could go both ways.

I agree. Eventually someone will sue for exactly that reason and agencies will have to do the cost benefit analysis of putting that back inot training programs.

Unfortunately one of things that will be considered is how many students would be excluded if a basic understanding of unintentional deco and the related gas planning and reserve awareness were included. Some OW certs do little more than prepare you to dive under the guidance of a DM and the industry benefits due to the increased number of (less highly trained) divers.

What I observed in the mid 80's was basically a dumbing down of the knowledge required of new OW divers and today's OW certs are much more like yesterday's Basic certifications - the step that preceded OW in some agencies - and the reason for it was to increase the potential market.

On the other hand it is hard to bash them too hard for that as the accident rate has stayed about the same so it appears that the less highly trained divers today are for the most part diving conservateively and or with better equipment and or DM support/supervision.

 

[don Francisco]

A dive computer is a tool which makes managing a dive easier, but is not a necessity. While I own and use a computer now, I dove many years using tables and the wheel for planning and managing my dives. Like you, I knew certain profiles by heart and at other times dove with crib sheets of the planned profile and alternatives in case I needed to modify the plan during the dive.

Even with the computer, I still find it easier to plan a dive with the wheel, and use the computer to manage the dive.

So count me among those saying that computers are not a necessity for those who have the ability and discipline to dive with tables. Besides ease, the main advantage of computers is that they allow extended bottom times. As a result, by eliminating the rounding which increases the saftey margin, they may actually make diving less rather than more safe.

As long as you're happy and successful diving with tables, go for it.

 

[MikeFerrara]

Here's some information for historical value only : Some divers have been known to average their depth in their brain (they say it becomes easy with practice), then add their bottom time to there average depth, and use a total of 120 as their NDL. They often change their exit strategy from, "head straight up to 15' for 3 mins", to stopping at 10' intervals for a minute on the way up, and then spending a long time moving up the final feet. No computer, long bottom times and they come out nice and clean.

Within limits, depth averaging works and it's easy enough to verify using decompression software. We're talking about a time weighted average, BTW. I don't use the 120 thing but I do average depths. I don't always use the straight average. When conditions make it seem like a good idea, I use a deeper depth opr even the max depth. Along with this, I dive profiles that I think are sensible (the nonsense being done at lots of resorts is NOT sensible, IMO, especially for older folks with questionable dive skills), use nice slow ascents and do some minimal decompression for all but the shallowest of dives.

All the precision that divers think they are getting with a computer is wishful thinking at it's worst, though it does sell lots of expensive but needless toys. While we can accurately measure depth and time and be precise about crunching those numbers according to some model, the ability of the model to accurately predict the effects on our bodies is still very limited. We're using a micrometer to measure what we're cutting with an axe.

To illustrate, simply examine some different tables (or computers) and note the wide variance. For a real education, get some decompression software and run some dives while varying the user selectable parms and see how DRAMATICALLY, the output varies.

 

[MikeFerrara]

We've had this converstaion about 100 different times and if one does a little searching they could fine many many pages on the subject along with some good info.

The OP mentioned the kind of dives he does and maybe talking some specifics would help?

I stopped using a computer when I started "technical" diving because the computers just didn't do what I wanted them to do. However, that's when I realized that, while I had been carrying a computer during my other diving, I hadn't really been using it, and didn't need it. As I think back through dives and dive sites, I couldn't even tell you why I ever baught a computer in the first place other than marketing hype that sounded good to me at the time.

 

[Dtaine]

I stopped using a computer when I started "technical" diving because the computers just didn't do what I wanted them to do. However, that's when I realized that, while I had been carrying a computer during my other diving, I hadn't really been using it, and didn't need it. As I think back through dives and dive sites, I couldn't even tell you why I ever baught a computer in the first place other than marketing hype that sounded good to me at the time.

I don't have many dives under my belt, but I rented one from a shop for a dive once to see if it was something I'd want to buy. I realized I didn't use it for anything other than keeping track of dive time. My watch does that and is quite a bit cheaper.

 

[MikeFerrara]

I don't have many dives under my belt, but I rented one from a shop for a dive once to see if it was something I'd want to buy. I realized I didn't use it for anything other than keeping track of dive time. My watch does that and is quite a bit cheaper.

That's about what I noticed but I don't like to make cost the issue. I've owned a bunch of computers and there's still probably 4 or 5 of them floating around the house or garage someplace that I could use if I wanted to.

 

[rstofer]

You would have been better served with at least owning a set of tables with deco information ...

The NAUI table contains a certain amount of deco information. For example: the NDL for 100 fsw is 22 minutes. The table also states that if you stay for 25 minutes there is a mandatory 5 minute stop at 15'. If you stay for 40 minutes, the stop time is increased to 15 minutes. So, you can nearly double your stay and still use table info for deco.

Although it was my practice to write the various ANDLs on a slate, I always carried my dive table in my BC pocket. Now that I have a BP/W, I am looking for a place to keep the thing. I miss it! Linus has his blanket, I have my table!

That, and there's no way these old eyes could read the table under water. I need to get diopter lens attachments or something.

I think divers would be well served to look into the NAUI tables. For one thing, all 3 tables are on the front of the slate. The back side has the graphic for doing the dive plan. There's no need to flip sides to handle the SIT.

Richard

 

[SurDo2]

Plan your dive and dive your plan...All I've ever used my computers for is a depth gauge and a bottom timer. They're convenient and cool but entirely unnecessary.

Later.

 

[nilsdiver]

Has anyone here given up the computer for one reason or another and just gone back to doing the math in the head?

For myself, I really don't miss it, but it was one of the things they told us we absolutely had to have.

My Suunto Vyper has been in gauge mode for over 2 years now. I like it better that way. And it has never limited me to square profiles yet.