Aeris Elite - Air Time Remaining

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Vegan Shark

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Location
Okinawa
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I just don't log dives
Anyone else question the accuracy of the calculations? I'll often be at 1000 PSI or so at 40 ft, and it calculates that I have 100 min remaining (I'm on double 100s, but even then there's absolutely no way I can get nearly 2 hours out of 1000 PSI). Is the algorithm assuming that I suddenly develop the sac rate of a corpse? I never use air time remaining for dive plans, so it's not that big of a deal, but man I wish I could breathe as little as it thinks I can!
 
I think your answer is yes you have a SAC rate of a corpse.

If I am correct you can not program the tank size and volume into the computer. As such it most likely uses the default of an aluminum 80@3000psi. That works out to .02666 cft/psi of consumption.

If you are using twin 100s or 200cft@3442psi that works out to .0581 cft/psi
So just using the twin 100s will throw the calculation off by over 50%
You will most likely have just under 1/2 what the computer tells you remaining.
 
It gives me completely different readings based on the tank size I'm using, so I think it doesn't go off of a default like AL80, but instead calculates based on how slowly the pressure is changing. But 50% of the computer's estimate usually feels about right. I wonder if "air time remaining" means air time until you reach 500 PSI, or 0 PSI.
 
Vegan,

I do not believe underH2O is correct. I suspect that you get different data depending on the tank you are using is because the rate the psi changes which is directly associated with the tank you are using. An LP80 should give you different times than an AL 80. I never considered the issue you adress because It was my belief that the tank size did not matter because it was computing how long , based on comsumption rate in psi, till you reached the min psi. IE 1000psi in tank and surface psi set to 400. you have 600 to use and you are using it at a rate of say 30 psi a minute. that gives you 20 min for the dive at that depth. So if youare using double 100s , the psi would drop at 1/2 the rate of a single tank. I would look at your configuration to see what you have set as the surfacing psi. If it is at say 100# then you have 900 psi to use till you hit min limit. That setting will effect time to surface calcs also. Now on the other hand if you are using an hp100's doubled. then at 1000 psi you have about30% of full tank and that would be about 65 cuft. How long do you think 65 cuft should last you at 40 ft and a min psi of nearly zero. If you have an air use of say .6 to .7 at 40 ft. (sac of .3 to 3.5) then you would have 100 minutes available. It sounds weird perhaps but i haver made 70 min dives at 80 ft before on an lp95 pumped to 108 and come up at 400 psi. Let me know what your configuration is set at.
 
Vegan,
Not sure if the Elite functions differently that an Aeris Epic, but are you sure the time remaining you are seeing as 100 minutes is the air time remaining and not NDL or O2 time remaining?

The little symbols are small, and they can be tough to see perfectly.

This being said, the Aeris computers are supposed to show the time (Air, NDL, O2) with the least amount remaining, so my statements above would seem to be counter to what your computer is showing, but thought I would throw it out as a possibility.
 

I agree with you regarding the computer showing the shortest time of all the factors. so if it was 100 m for O2 then the air remaining wold be even longer. has to be sac of a corpse.



Vegan,
Not sure if the Elite functions differently that an Aeris Epic, but are you sure the time remaining you are seeing as 100 minutes is the air time remaining and not NDL or O2 time remaining?

The little symbols are small, and they can be tough to see perfectly.

This being said, the Aeris computers are supposed to show the time (Air, NDL, O2) with the least amount remaining, so my statements above would seem to be counter to what your computer is showing, but thought I would throw it out as a possibility.
 
It's definitely air time remaining, and not NDL or anything else. I'll check the setting, but I haven't changed them so it should be on default, which I'm assuming is around 500 PSI. Will take a picture of the air time remaining reading when I go diving in a couple days.

Any idea if it uses your average sac on that dive to calculate, or your lowest recorded sac?
 
Vegan,

I do not believe underH2O is correct. I suspect that you get different data depending on the tank you are using is because the rate the psi changes which is directly associated with the tank you are using. An LP80 should give you different times than an AL 80. I never considered the issue you adress because It was my belief that the tank size did not matter because it was computing how long , based on comsumption rate in psi, till you reached the min psi. IE 1000psi in tank and surface psi set to 400. you have 600 to use and you are using it at a rate of say 30 psi a minute. that gives you 20 min for the dive at that depth. So if youare using double 100s , the psi would drop at 1/2 the rate of a single tank. I would look at your configuration to see what you have set as the surfacing psi. If it is at say 100# then you have 900 psi to use till you hit min limit. That setting will effect time to surface calcs also. Now on the other hand if you are using an hp100's doubled. then at 1000 psi you have about30% of full tank and that would be about 65 cuft. How long do you think 65 cuft should last you at 40 ft and a min psi of nearly zero. If you have an air use of say .6 to .7 at 40 ft. (sac of .3 to 3.5) then you would have 100 minutes available. It sounds weird perhaps but i haver made 70 min dives at 80 ft before on an lp95 pumped to 108 and come up at 400 psi. Let me know what your configuration is set at.

I believe KWS is entirely correct. I've been diving Oceanic computers since 2001, a VT3 since 2010. I've used many different types of cylinders from Al 80s through steel 133s. I do not dive doubles. The ATR has always been pretty accurate and when ATR hits zero, you should have your entered surfacing psi left after making a normal ascent and taking your SS. The ATR will only be on the primary screen if it is controlling the duration of the dive remaining, otherwise it may be NDL or O2. If it is the NDL, for instance, ATR will be displayed on the alternate screen. Take a look at your owner's manual, probably available as a download like Oceanic is if you don't have your paper copy.
 
Your dive computer does not know your SAC. all it has is tank presure from the transmitter to go by. It will figurativly log your tank pressure every minute and then use the difference from the last reading to compute time remaining. I have an elite and a t3 elite. I gave them both up for shearwater's You can use the software that came with the dive computer to run on your desktop computer to show you your SAC. To get it you have to enter the tank size. So for your double 100's you will have to enter 200 cuft and the working presure of 3442 that gives you the 200. the computer takes it form there, looks at your depth and tells you your SAC.


It's definitely air time remaining, and not NDL or anything else. I'll check the setting, but I haven't changed them so it should be on default, which I'm assuming is around 500 PSI. Will take a picture of the air time remaining reading when I go diving in a couple days.

Any idea if it uses your average sac on that dive to calculate, or your lowest recorded sac?
 
Your dive computer does not know your SAC. all it has is tank presure from the transmitter to go by. It will figurativly log your tank pressure every minute and then use the difference from the last reading to compute time remaining. I have an elite and a t3 elite. I gave them both up for shearwater's You can use the software that came with the dive computer to run on your desktop computer to show you your SAC. To get it you have to enter the tank size. So for your double 100's you will have to enter 200 cuft and the working presure of 3442 that gives you the 200. the computer takes it form there, looks at your depth and tells you your SAC.

Again, KWS is entirely correct. You designate the cylinder size and operating pressure in the Oceanlog software and the SRMV (SAC) is then calculated using the start and finish cylinder pressure, dive time, and average depth. The Oceanlog software allows you to designate a default cylinder and to save as many other cylinders as you use. I have half a dozen cylinders saved.
 
https://www.shearwater.com/products/teric/

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