Any proof that dive computers improve safety?

[njedrn]

Research on this topic would be very difficult to undertake - The study would have to be retrospective from point when someone used a chamber or was diagnosed with dcs, then look back at their dive profile/plan... and as gcbryan put it... if that person was not using a computer it would be almost impossible to get an accurate account of depths, times and plan.

 

[*dave*]

That would be a telling statistic for recreational dives. I would think the make and model of computer or whether the dive was on tables is recorded for each case.
[edit] No it wouldn't... Without the number of non DCS dives and the number of dives conducted using tables and computers, there's no basis for a conclusion. If more computer divers are getting DCS is it because computers are less safe or becasue there are more computer divers?

Pete,
A simple stats like the percentage of DCS divers who used comps vs. overall percent divers using comps will do. Or a decline in number of DCS cases per 10,000 dives per
year, if it correlates with % of dives with computers. I am pretty easy to be convinced :blinking:

 

[rstofer]

Not exactly, Richard. Their rules can be trumped by certification agencies, if these are interested, of course.

There isn't an agency that I have heard of that is willing to state that computers are unsafe. Some agencies are running away from tables.

Dive boats certainly haven't reviewed EVERY agency's rules. Why would they care? You signed a release before you got on board.

You can't expect to SIT around for a couple of hours waiting for your tables to clear while the computer divers are ready to go. Although I see no reason why the boat wouldn't let you SIT out the entire dive. But scheduling other divers around your tables just isn't going to happen.

This just isn't a big deal. Get a computer and be done with it!

Richard

 

[HowardE]

Not exactly, Richard. Their rules can be trumped by certification agencies, if these are interested, of course.

The boat's rules can be "trumped" by an agency? I don't think so.

There are no "agency agents" that are going to come and check up on them? Scuba is an unregulated activity. There are no scuba police.

This is simple really. If the liveaboard you're going on requires a computer... Either get a cheap computer, or find a different liveaboard.

 

[tarponchik]

Wearing a computer and having DCS or not wearing a computer wouldn't tell you anything.

Yes it will, if I know how often divers use comps.

 

[DaleC]

That has a bunch of dangers associated with it, especially with respect to muti-day multi-dive profiles and flying after diving. Good term, we call it, "riding the bubble up."

Yes, with a single tank I never really encountered the phenomenon before (gas limited) but since I switched to doubles it became possible to really ring the last drop of NDL out of my computer. It got me to thinking about how I was bulking up on N compared to a square(r) profile.

An area where I think this can screw someone up is if they are using the tables to calculate SI's during pre dive planning. (which I sometimes do). One could plan repetitive dives and calculate the SI needed for the max depth/time anticipated then dive the planned max depth/time. But if they "ride the bubble up" as you say they would in reality need a longer SI. Not a problem once the diver recognises what is happening but an easy slip the first time you do it.

Unlike bulking up with protein shakes which can make you a "Terminator" bulking up on N can just make you "Terminal".

 

[tarponchik]

Either get a cheap computer, or find a different liveaboard.

Great advice, and so highly original. Thanks.

 

[H2Andy]

A simple stats like the percentage of DCS divers who used comps vs. overall percent divers using comps will do. Or a decline in number of DCS cases per 10,000 dives per year, if it correlates with % of dives with computers.

so you are equating "safe diving" with "no DCS diving"

since the incidence of DCS is so miniscule to begin with, and since statistics are not kept as to who got bent when and whether they were using a computer, you'll never get an answer this way

also, since almost everybody wears a computer these days, you'll probably find that almost every diver who got bent was using a computer

does that mean using a computer is unsafe?

another way to measure "safe diving" is "number of dead divers using computers vs. number of dead divers not using computers"

you could try counting how many divers who die in a year died using computers, and i bet it will be close to 100% since almost everybody wears a computer these days

does that mean that wearing a computer is inherently unsafe?

 

[HowardE]

Great advice, and so highly original. Thanks.

Anytime.

My opinion on if a computer is safer?

Safer than what? Any diver can get bent, once you dive deep enough to exceed the 2:1 (or as some say the 1.6:1 pressure gradient). Dive computers or dive tables don't take into account your physical condition prior to diving. Are you hydrated, well rested, in good shape, hungry, high blood sugar, low blood sugar, high blood pressure, etc.

Computers maximize bottom times by giving you a more realistic picture of depth and time, as to approximate your no decompression and/or decompression obligations at any given moment on the dive. This by no means makes it safer.

Tables include a lot of rounding off, and generally give you less bottom time, since they assume a square profile, and theoretically you should plan for your deepest depth, and round up your time to the next time unit on the dive, thus you're actually diving a shorter time than the table is accounting for, and at a shallower depth than the table is accounting for, and logic would follow that this is a more conservative approach, and logic would also follow that conservatism is safer.

At the same time; if the boat wants a computer, then the rules is the rules. It's their boat after all. Right or wrong... It is what it is.

 

[tarponchik]

If more computer divers are getting DCS is it because computers are less safe or becasue there are more computer divers?

This is fairly easy.

1st, DCS cases are recordered, and my understanding is they are also investigated to some extent, so they probably record if the diver used computer or not. So you know in what % of DCS cases the divers used comps.

2nd, you can get an estimate of how often comps are used per number of dives. You don't have to check records of all dives in the world for this, just test a representative sample by asking a number of divers to check their logs. Provided that your sample of divers is random, you get your estimate of % dives with comps.

3d, you compare the two numbers and check if there is a statistically significant difference between them. If there is, you know the answer. If there isn't, then you do not.