Are some computers unsafe?

[fnfalman]

How does a dive computer keep a diver safe while that diver is fine tuning his or her control?

The computer doesn't control how I dive. If I were to want to go to 300-ft on an HP80, then that's what I'm going to do. If I were to rocket to the surface then that's what I'd do. The computer can't stop neither.

 

[boulderjohn]

The most conservative dive plan is to stay in bed. Whether it is tables or computers, we want to use the one that gives us the best balance between allowed bottom time and safety. Right now there is no good data on the relative safety records of different computers. What that translates into in terms of your question is that there is no computer that has been shown to be unsafe.

 

[drrich2]

It can warn you when something's amiss, sometimes. Such as a custom settable depth alarm. I've seen a newbie in Bonaire head down the reef & go much deeper than planned; on a separate trip saw a recently cert.'d nitrox diver on EAN 32 drop down about 130 feet to get on the same level with a big Hawksbill sea turtle, not realizing how deep she was getting.

You can set some dive computers to sound an alarm at a given depth limit or PSI remaining. That's not a good substitute for being mindful of depth & pressure yourself, but it can be a back up measure.

Richard.

 

[ianr33]

Is a Ferrari unsafe because it is capable of going faster than a Toyota Corolla?

Know your computer and dive it in a way that is safe for you.

 

[mala]

Is a Ferrari unsafe because it is capable of going faster than a Toyota Corolla?

Know your computer and dive it in a way that is safe for you.

i would say that you are much more at risk of a nasty rash in a farrari that a toyota.

 

[Mr Carcharodon]

The two models are based on data from different types of diving. The Suunto uses an algorithm that is based on data consisting mostly of deep, repetitive cold water dives at altitude. The DSAT model (likely the one you used in the OC1, although you could change the algorithm) is based on data consisting primarily of no deco, multilevel, repetitive dives at sea level.
Good luck!

Boy I am lost on this. Maybe you could expand.

Both bubble modes (e.g. RGBM) and dissolved gas models (e.g. DSAT) calculate tissue loading exactly the same way. They set limits differently. DSAT sets pressure limits, RGBM also uses volume limits. AFAIK RGBM did no independent testing to come up with the model parameters used, but rather calculated the volumes that corresponded to the pressure limits in the other models to come up with a new type of limit (i.e they backed into values using available data). RGBM makes some volume adjustments for repetitive dives, sort surface intervals etc. That gives RGBM some capability to address novel situations, but it appears given the track record that the adjustments may be overly conservative. If there is anything that documents that different sets of data were used I would like to hear about it. Or at least that is my just so story. If it is wrong someone can point in the right direction.

 

[supergaijin]

Is a certain style or brand of handgun inherently unsafe?

Different algorithms are incredibly complex and no mathematical computation can monitor all the chemical responses inside the body from individual to individual. Computers are what they are- a pretty way of estimating the human body's nitrogen absorption on a given dive profile.

Deco for Divers by Mark Powell is a great book to start getting in to the various aspects of different decompression theories that exist. Even for someone with a bad head for maths (like me), one can at least learn something from it. Recommended.

 

[Karibelle]

Boy I am lost on this. Maybe you could expand.

Both bubble modes (e.g. RGBM) and dissolved gas models (e.g. DSAT) calculate tissue loading exactly the same way. They set limits differently. DSAT sets pressure limits, RGBM also uses volume limits. AFAIK RGBM did no independent testing to come up with the model parameters used, but rather calculated the volumes that corresponded to the pressure limits in the other models to come up with a new type of limit (i.e they backed into values using available data). RGBM makes some volume adjustments for repetitive dives, sort surface intervals etc. That gives RGBM some capability to address novel situations, but it appears given the track record that the adjustments may be overly conservative. If there is anything that documents that different sets of data were used I would like to hear about it. Or at least that is my just so story. If it is wrong someone can point in the right direction.

I think you're right - perhaps I overstated it. There are dive data that support the RGBM theory - as opposed to dive data that preceded the theory (although it's my understanding that the model arose to meet the needs of technical divers and staged decompression). Those data consider factors not clearly considered in the DSAT model, and in many cases not relevant to recreational divers. Like decompression dives, altitude dives, cold water. My point remains this: what type of diving you plan on doing should influence your computer choice. If you're planning on doing multilevel, repetitive dives with significant surface intervals, at sea level (what I'd think of as "easy, recreational" diving) then the DSAT model will give you the most bottom time within acceptable level of risk. if your diving includes those factors that were considered in RGBM modeling, then perhaps that model is appropriate for you. If you'd like to do what I think of as "easy, recreational" diving with an added layer of conservatism, perhaps the RGBM model is for you.

 

[fnfalman]

I think you're right - perhaps I overstated it. There are dive data that support the RGBM theory - as opposed to dive data that preceded the theory (although it's my understanding that the model arose to meet the needs of technical divers and staged decompression). Those data consider factors not clearly considered in the DSAT model, and in many cases not relevant to recreational divers. Like decompression dives, altitude dives, cold water. My point remains this: what type of diving you plan on doing should influence your computer choice. If you're planning on doing multilevel, repetitive dives with significant surface intervals, at sea level (what I'd think of as "easy, recreational" diving) then the DSAT model will give you the most bottom time within acceptable level of risk. if your diving includes those factors that were considered in RGBM modeling, then perhaps that model is appropriate for you. If you'd like to do what I think of as "easy, recreational" diving with an added layer of conservatism, perhaps the RGBM model is for you.

Do you have any scientific research and theory to back up this claim that RGBM is safer than DSAT?

Otherwise, it's a rather spurious claim.

 

[crls]

No computer is unsafe, is the behavior of the user which is unsafe in related to the tool is using. A computer is a tool, you should understand how to use it, which are the algorithm that it used (the computer) and so on, and make your diving decisions upon it.
No matter what computer or brand you have, you computer is a backup of your brain, which is your primary dive computer. That is why you should study tables, models, physiology, make your own statistical analysis of your dives and use the same gases. There is no substitution for study and practice.

---------- Post added ----------

The validations on a model depends of the criteria in which the sample universe are acquired. Since model building and validation both require samples and the statistical assessment of the performance of a predicting scoring model can be highly sensitive to the data set acquired.

Boy I am lost on this. Maybe you could expand.

Both bubble modes (e.g. RGBM) and dissolved gas models (e.g. DSAT) calculate tissue loading exactly the same way. They set limits differently. DSAT sets pressure limits, RGBM also uses volume limits. AFAIK RGBM did no independent testing to come up with the model parameters used, but rather calculated the volumes that corresponded to the pressure limits in the other models to come up with a new type of limit (i.e they backed into values using available data). RGBM makes some volume adjustments for repetitive dives, sort surface intervals etc. That gives RGBM some capability to address novel situations, but it appears given the track record that the adjustments may be overly conservative. If there is anything that documents that different sets of data were used I would like to hear about it. Or at least that is my just so story. If it is wrong someone can point in the right direction.