Computer with manual AI?

[Doctor Rig]

I’m in the market for a dive computer and I find computers with and without air input (AI). AI is either wireless or by hose. Are there computers that that allow the diver to manually input the tank pressure when the diver wants to know his real dive status without the added cost of AI. Seems like this capability would be an easy capability to add and be a cost effective option for sport divers. Why is this not offered..... or what am I missing?

 

[hhmoore]

Real dive status?
Without air integration, the tank pressure that the diver would input would be an approximation of a gauge reading...doesn't seem like the best way to get "real" quantification of anything, even if it is budget friendly.

 

[Joneill]

I’m in the market for a dive computer and I find computers with and without air input (AI). AI is either wireless or by hose. Are there computers that that allow the diver to manually input the tank pressure when the diver wants to know his real dive status without the added cost of AI. Seems like this capability would be an easy capability to add and be a cost effective option for sport divers. Why is this not offered..... or what am I missing?

I’m not sure what you are really trying to do? What would be the point of manually adding air pressure info into the dive computer? If you want it for historical info, most dive log programs allow you to add start and end pressure to each dive when you download them.

 

[KeithG]

Maybe provide a more complete explanation of the problem you are trying to solve?

Your explanation has me confused. Do you want to enter pressure at the start, during or after a dive. Where do you intend to get the pressure information?

 

[CT Sean]

A dive computer can't "know" a diver's "real status" without some connection - wireless or hose - to the tank. Even if one could input a starting tank pressure and estimated SAC, it would be static calculation that the computer provides with no consideration for the conditions of the dive itself. IMO, this is way too dangerous to include as "cheap AI" (especially since it's not air integration at all) and it's probably good that it's not an available option.

 

[Doctor Rig]

Thanks for asking clarification request questions!

As I understand it: From a macro perspective, computers without tank pressure input are not significantly safer than gauges and a watch. Computers with tank pressure input, give the diver actual remaining dive time and instructions with considerations to depth, time at depth, stops, etc.

My thought is why aren’t there computers that allow a diver to input tank pressure, and have the computer run the calcs on-demand, using recorded dive history, to guide the diver. A computer with AI, tank pressure, does this continuously real time, but as proposed this manual input would provide the same diver input as a computer with AI, but only on-demand (upon inputting tank pressure).

Wouldn’t sport divers, with gauge pressure data, be in better control of possible dive time and safe assents with this cost effective ability to obtain on-demand dive status information?

Seems like this proposed computer on-demand configuration should be (or maybe already is) on the market, but I haven’t found it.... IMHO.

 

[jgttrey]

Nothing like that out there and i think it would be very cumbersome and of very limited value.

AI computers generally calculate GTR on the basis of a rolling "snapshot" of the rate of PSI change. For example, it might look at the amount of PSI change over the past minute or 90 seconds and extrapolate based on that rate of depletion at the current depth and ascent profile. Thus, the computer itself, generally, is ignorant of the actual volume of gas being consumed (i.e., tank volume doesn't figure into it). It's just looking at a snapshot of how fast the gas gauge is dropping.

Thus, without changing the algorithm, you'd have to enter a series of pressures -- which, unless the data points are spaced pretty far apart, would have to be very precise to yield useful information.

 

[CT Sean]

Thanks for asking clarification request questions!

As I understand it: From a macro perspective, computers without tank pressure input are not significantly safer than gauges and a watch. Computers with tank pressure input, give the diver actual remaining dive time and instructions with considerations to depth, time at depth, stops, etc.

I'm not sure there's any truth to a non-AI dive PC being no safer than tables. If you have actual data to suggest otherwise, feel free to share it. I'm also not sure there's any statistically valid data to suggest that diving with an AI computer is safer than non AI.

My thought is why aren’t there computers that allow a diver to input tank pressure, and have the computer run the calcs on-demand, using recorded dive history, to guide the diver. A computer with AI, tank pressure, does this continuously real time, but as proposed this manual input would provide the same diver input as a computer with AI, but only on-demand (upon inputting tank pressure).

Without reading actual tank pressure, such a calculation would be a "guess" by the computer based on input tank pressure and SAC and could be wildly inaccurate based on dive conditions. If the suggestion is that a diver would enter multiple tank pressures over the course of the dive, as suggested above, that just seems like unnecessary task loading and time that could be better devoted to simply paying attention to one's gauges.

Wouldn’t sport divers, with gauge pressure data, be in better control of possible dive time and safe assents with this cost effective ability to obtain on-demand dive status information?

I don't see why - it doesn't take much for a recreational diver to know when they should start ascending to avoid exceeding NDL and/or gas remaining. And is a diver who can't do this really gonna be "trusted" to follow a calculated dive time remaining which is, as best, a rough estimate? I find it hard to believe that there's a notable portion of divers that are paying appropriate attention to their gauges and have OOA emergencies anyway -outside of equipment failure of course, but DTR/GTR is't gonna help in those cases either.

 

[Doctor Rig]

@jgttrey..... good point, not considered. One possible solution to this would be to enter start and ending dive pressures. After maybe 10 dives the computer could have calculated a reliable consumption rate, but that would be diver specific of coarse. Seems like there could be some possible work-arounds, but healthy safety factors could/should be integrated.

On the flip side, if you don’t have a computer at all, there’s lots of guess work involved, which could easily be called unsafe today.

 

[Doctor Rig]

Thanks for the input. Your valuable experience appears to refute the value of my proposed on-dmemad based computer.... and you’ve clarifed that no such thing exists today, which is most helpful to me in itself!

No telling where the future will take this issue. Should be interesting!