Pushing your computer to the limit

[yknot]

I'm posting this in response to a question in the instructor's area. As I'm not an instructor, I can only post here. The question was about the wisdom of diving your computer into the yellow. First, prior to my opinion, I would say to take a look at the dive planning mode of your computer. Some models, when asked for the allowable time for a given depth, will automatically respond with a plan into at least the last tick in the yellow, if not the red zone. I would take this as the manufacturer's belief that the algorithms in use are sufficiently conservative to do so. As far as if it is safe or wise to do so, what do you recall from your basic open water training? Do you think that a computer or even some dive tables can prevent DCS or some other dive injury, just because you "keep it in the green" or follow the time and depth limits from a chart? Part of the relevance of this question too is the current drift to computer use. I don't want to revive the "computers rot your brain" arguments but consider the fact that computer awareness and use is now part of basic open water training with some agencies. At some point, a computer may be considered essential gear, just like an octo or BC is now. Partly, I would like to believe that the true reliability of todays newer dive computers is the cause but the cynic in me believes it is more due to an attempt to get new divers comfortable with the technology early on so as to sell more computers and also, by de-empasising the tables, shorten the training time and make it easier to become certified.

 

[The Chairman]

Circumventing teaching tables will not "shorten" the learning time much. Tables only take an hour to teach and master for a group of 4-6. It depends on how clear and accurate you are as you teach it.

You are only at risk of DCS when you dive... it doesn't matter if you use tables or a computer. Both of these are tools to manage that risk... nothing more. There are so many factors that contribute to a person's predisposition to DCS that have nothing to do with tables/computer: hydration, fitness, health, exercize, etc.

 

[bcsean]

I'd have to say I was actually surprised computers weren't covered more in my OW class a few years back. I think too many people buy computers and use them without understanding what they really do. Teaching tables is still fundamental though as it allows a new diver to understand the models that the computers are based on. Plus, not everybody can afford a computer right away and still wants to dive.

Also good to understand how conservative your particular computer is. I know Suunto's are generally quite conservative which is what I dive. I've yet to break the NDL.

 

[Quarrior]

Teaching the tables in the OW class IMHO is done because they are standard for the agency teaching the class. Teaching computers would be next to impossible because of the variables in all the makes and models of the computers.

It would be kind of like teaching the use of DOS and then having the student go out and buy a Mac. They both do the same thing, but function completely different.

 

[The Kraken]

In my humble opinion, yes, I'm about to beat the "use your tables" drum again, one of the problems with a dive computer is that, once purchased, may divers never again use a dive table to plan a dive.

When I first got my dive computer one of the first things I did was check the computer against my dive profile. I dove a square dive profile and check the green/yellow/red marks against the planned dive time.

What I found, without going into unnecessary detail, is that the top of the red area corresponds to the NDL for that dive. The colors are there to alert the diver to the approach of the particular limit. Once a diver hits the top of the red then the computer alert will sound designating end of dive.

I think many computer divers misconstrue the red area to mean death is knocking on the door.

 

[RonFrank]

Part of the relevance of this question too is the current drift to computer use. I don't want to revive the "computers rot your brain" arguments but consider the fact that computer awareness and use is now part of basic open water training with some agencies. At some point, a computer may be considered essential gear, just like an octo or BC is now. Partly, I would like to believe that the true reliability of todays newer dive computers is the cause but the cynic in me believes it is more due to an attempt to get new divers comfortable with the technology early on so as to sell more computers and also, by de-empasising the tables, shorten the training time and make it easier to become certified.

Computers have been credited with descreased diving accidents.

Computers are based on the diving tables.

One could argue that a using a TABLE is really not good as one does not have to understand the math behind the table.

PADI which is the largest cert agency for new divers requires using the tables. They are however (according to the Master Instructor I learned with) considering changing the cert to a computer based learning. ClassRoom/ConfinedWater/Testing/OW take four days. This assumes that the student walks in the door with a full understanding of the TEXT. Not sure how using computers vs. a table would shorten that.

Computers do not prevent idiots from doing stupid things. However which is safer, someone who does not bother to understand tables WITH a computer, or the same without one?? The instructor I learned with carries two puters as his backup. He plans his dives based on the puter and software.

The goal is safe diving. I'm betting that the majority of people out there diving on a regular basis plan their profiles to some degree AND use puters. I'm guessing that the majority of divers out there without a clue generally use a Service where others plan the profile, or limit the BT.

Pushing the NDL is foolish, and does it matter how that is done?

It really does NOT have anything to do with what tool is used to push a limit does it, and computers are arguable MUCH safer than not having one??

Ron

 

[Bob3]

The dive computer as a safety hazard:
Computers let a person load right up to the hairy edge, often with a false sense of security.
Pushing the NDLs over multiple dives on a daily basis, as when on vacation, can put a person at greater risk for one of those so-called "undeserved hits".

 

[miketsp]

This is a question which can't really be answered without knowing which computer you're talking about. My wife and I dive with 2 computers of different brands. One is considered by many to be conservative, the other older, is much more aggressive and to make the latter come close to the tables I first learnt on, I have to use the interface to up the safety factor to about 20%.
And I know people that have been on chamber rides diving this model to the limit.