AVG depth on the fly?

[rivers]

Any air-integrated computer will give you "Air Time Remaining". As a DM you should have pro-level equipment. Including an air integrated diving computer.

Or if you know your own SAC rate, you can determine your own air time remaining, and not rely on a computer to do it for you. That, in my mind, is more professional than relying on a computer. As a DM, I don't dive with a computer. Just a bottom timer and some tables. Although, most of the time, I know my plan without looking at tables as most of my "fun" dives are similar in profile (30m for anywhere between 30 and 45 minutes depending on conditions).
Anyway, back to the topic at hand. I use average depth on every dive, but my xen gives it to me. However, most of my dives don't have a massive difference between the sea bed and the top of the wreck.

 

[Remy B.]

I wouldn't wanna go diving with that kind of punk...

Don't get confused as well, it shows current depth and at the end of your dive when you check the log it shows the average depth

 

[Kevrumbo]

All my wall dives in 29deg C Palau waters are averaging 20 meters which is 3 ATA (divide 20m by 10 and add 1 gives 3ATA); going with the current, my Surface Consumption Rate (SCR) is a low 11 liters/min; divide 11 liters/min by 11 liters/bar (AL80) cylinder tank rating and you get a 1 bar/min pressure rate; multiply 1 bar/min by 3 ATA average depth yields a pressure Depth Consumption Rate (DCR) of 3 bar/min Checking my bottom timer every 10 minutes, I expect to consume 30 bar (3 bar/min multiplied by 10min equals 30 bar), and accordingly my SPG should read 30 bar less in that 10 minute time frame.


So by 30 minutes elapsed dive time at 20 meters, I expect to be down 90 bar or at half tank (AL80 full tank is 200 bar). At 40 minutes elapsed time, I'm ascending off the wall into the shallow coral plateau around 9 meters (down 120 bar from 200 bar total, or 80 bar remaining in tank). And finally at the 45 to 50 minute mark, I'm at 6m and my 3-5min safety stop with 60 to 70 bar left. I surface and I know even before looking at my SPG that I have around 50 bar remaining in my tank.


This is how you should actively use your SCR with your particular tank, knowing how much breathing gas you have left not only on pre-planning, but also during the actual dive at depth, real-time-on-the-fly --all with easier to use metric units . . .additionally, you have a SPG that reads in units of pressure: why not convert your SCR to a Depth Consumption Rate (DCR) in pressure units to make use of it???

 

[boulderjohn]

Going back to the original question....

My training group was taught to check their depths regularly and maintain a mental arithmetic process to keep track of average depth. That average was used to calculate the ascent profile. I had two friends who checked their actual computer profile after such a dive. One of them had used a computer in gauge mode during the dive, so he had the actual profile to compare with the one they calculated on the fly. They discovered a fairly significant difference between what they had calculated as their average depth and the actual average depth as calculated by the computer. The reason they were comparing is that they were trying to find good reasons that they both got bent.