Very good dive,B.Z, just curious, where did you do this dive and what were the water temps, thermoclines etc?
Average total dive depth to estimate your surface Gf
- Thread starter jale
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GF99/99
Contributor
Nice dive
This relationship between total avg depth and surf gf is a pattern and then it needs a lot of similar dives for you to see if you can see something constant.
It is just an observation you may find and that you may use to give you a kind of awareness of your position in the dive.
Sorry I don't know why but I must be having one of those brain fart days. I still am not understanding how my average depth has any relationship to my surface GF. I understand this is just a ball bark estimation tool but I just am not understating what were estimating. Are you saying my surface GF should be around 27??
I usually dive 40/85 or 50/85 so naturally every time I finish a dive/clear deco when I get on the surface my GF is usually 84'ish how does this relate to my average depth? And obviously during the dive my surface GF is constantly changing based on depth, time, gas so at what point in time are we guessing our surface GF
No total avg dpth doesn't equal to surf gf
Total avg depth means you have almost completed your dive and you (at least I) look at it near the end of the last deco stop. When I look at it I expect a number which I have seen many times and which serves at giving another way to validate that I think is correct relatively to my previous experiences.
Just indeed a "ball bark estimation tool", nothing more and nothing "scientific".
Hope that helps
As mentioned, you need to compare many dives and see what trend may be happening ... but, once you start to change parameters (gas types, GFHI, etc), it will change the outcome as well....
It isn't exact, but it is a ballpark figure .... once you start comparing profiles, you may see a trend, you may not ..
Here is a very simple look at some normoxic dives, 18/45 with 50% over 39,45,51m depths for 30min with a GF of 50/85
These end up around 23-25m Average depth ... once could look into it more and run more depths, or durations to figure out how those numbers change .....
Again, this is no way exact, or even as close as a resolution to say a shearwater or other computer running actual GF! Just another tool (mainly for exercise) in case ...
Call it voodoo, nonsense, something that doesn't exist, or ancient ... I just know when my average depth for the dives that I'm doing, if they are deeper than 22-23m, I'm not feeling that energetic later in the day than a diver where the average depth ends up a little shallower (same GF, same gases, etc ...)
_R
The other way I use it is for future planning...
Say, like as I said above, I know I feel better post dive with a 21m average depth for a certain range of profiles.
If I start to plan for a different profile, I can see what the GF might do to the average depth, and adjust more conservative for that new profile, until I dive that profile a while and can then move the GF around to better suit (an I maybe doing too much deco? Not enough?) and see what that average depth number may be for that style of profile...
_R
Say, like as I said above, I know I feel better post dive with a 21m average depth for a certain range of profiles.
If I start to plan for a different profile, I can see what the GF might do to the average depth, and adjust more conservative for that new profile, until I dive that profile a while and can then move the GF around to better suit (an I maybe doing too much deco? Not enough?) and see what that average depth number may be for that style of profile...
_R
Because... <<drum roll>>
Your 21m average depth has a surfGF in the 75-80% range vs the 23-25m average ends up having a surfGf around 85
The more time you do shallow, you are dragging the average up shallower, you are lowering your final GF.
Averages of anything are heavily influenced by the "big" numbers, in diving those are the bottom phase. You have to have more of the small number (the shallow stops) to compensate for the few big BT minutes.
If your average depth is 30m I can almost guarantee you haven't finished deco or its very aggressive.
Ever the skeptic, this seems more like astrology and coincidence than anything meaningful.
Are you still stuck doing those square profile table dives? Want a PADI wheel to get out more?
Your Gradient Factors?
I understand your point but precision doesn't always mean accuracy.
Your computers are indeed precise but is it not good to also have some kind of "trick" to help you to have a general validation of the numbers you are reading?
It is like having a GPS and telling people it is useless to be able to know where is the North just by being aware of the way vegetation grows.
I think all knowledge is good.
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