Any Average Depth tables available?

[kramynot2000]

Sitting here counting the hours until I leave for Florida for the holidays ( <72 hours now) I was looking over my past few dives on my Citizen Hyper Aqualand watch, which records both max depth and average depth. So, I started wondering whether there are any tables available that calculate NDLs based on average depth of a dive.

I don't think you could use the standard PADI tables since a square profile dive of say 100' would actually have a slightly shallower average depth once you calculate in the descent and ascent. I guess you could take average depth and pad it by say 5% or 10%.

Anyway, anyone know if average depth tables are available or anyone use average depth with standard PADI, NAUI, etc. tables?

 

[Scuba_Steve]

Hey Tony.

[DISCLAIMER]
Certainly not scientific, and I wouldn't want anyone trying it because this is how I do it, but........[/DISCLAIMER]

Work out your own average depth, including the time factor spent at the various levels, and then use that as your depth when going to tables for your NDL.

I'm speaking directly to recreational diving, (depths, NDL etc).

For an example: A dive to 100ft for 10mins, and then a move up to 80ft for 10 mins will result in roughly a 20min, 90ft dive as far as NDL is concerned.

It's close enough that I don't worry about it. YMMV.

See for yourself with your own computer's numbers. I'm sure you could extrapolate this kind of info from it as well.

Steve

 

[The Kraken]

The concept is nice, but what screws up the issue is the time at each depth.
You could have a dive that had an average depth of 50 feet, but 80% of the total dive time could have been spent at the lower depth.

To use a table you would have to know all of the times that you would spend at specific depths beforehand in order to use a table. The combinations and permutations of such a table staggers the mind.

 

[Uncle Pug]

Planning the dive before hand using an average depth available from your Aqualand after the dive would require a call to Psychic Friends Hotline.

 

[The Kraken]

Planning the dive before hand using an average depth available from your Aqualand after the dive would require a call to Psychic Friends Hotline.

:lol3:

Toooooooooooooooo funnny !!!!

 

[Scuba_Steve]

The concept is nice, but what screws up the issue is the time at each depth.
You could have a dive that had an average depth of 50 feet, but 80% of the total dive time could have been spent at the lower depth.

To use a table you would have to know all of the times that you would spend at specific depths beforehand in order to use a table. The combinations and permutations of such a table staggers the mind.

I was trying to keep it simple for the guy, but yes you're right about the time, which is why I said time at each depth is important.

Sorry though folks, you're going to have to figure out that part by yourself I'm not giving the whole "secret" away!!

As for all the table "combinations and permutations", it's way easier than that too. Didn't we have this discussion a few weeks ago in another thread?

I'd say trust me, but I don't want you to. But I trust me , and I do it all the time, on every "Rec NDL dive", without exception.

As for my buddy Uncle Pug,.....While I agree with the plan your dive thing (doesn't everybody??) you can do this during the dive quite easily too. Not too tough at all. It works when you're not entirely sure of the depth/time you will be at during each level of the dive. (Drift in Coz for example). You'll more than likely know the depth, but unsure of the times spent there until you're actually doing it. Hmm, "NDL on the fly"

Steve

 

[kramynot2000]

:lol3:

Toooooooooooooooo funnny !!!!

Yeah, yeah, yeah, I know that

I was actually thinking about using average depth from the first dive to plan my NDL for a second dive.

I do kinda do what scuba_steve says and kinda figure what my depth was and then look at the tables.

This watch actually calculates average depth based on time at each depth. So this last weekend I was diving off a boat in Monterey and had a max depth of 60' for 40 minutes. Average depth was 42' according to the watch. I was just thinking that it'd be nice to actually use the 42' to calculate NDL for the second dive.

 

[Dr Deco]

Hello kramynot:

It is difficult to make something based on averages since gas uptake is irregular. For example, 20 minutes at fifty feet is not equivalent to 10 minutes at 100 feet.

Dr Deco :doctor:

 

[kramynot2000]

Hello kramynot:

It is difficult to make something based on averages since gas uptake is irregular. For example, 20 minutes at fifty feet is not equivalent to 10 minutes at 100 feet.

Dr Deco :doctor:

Thanks Doc. I guess this answers the science question that was hidden behind my layperson's question.

Well I guess I should get back to work.... or not....

 

[Scuba_Steve]

Hello kramynot:

It is difficult to make something based on averages since gas uptake is irregular. For example, 20 minutes at fifty feet is not equivalent to 10 minutes at 100 feet.

Dr Deco :doctor:

No one is saying to do it that way dude.

That would be just plain wrong for too many obvious reasons.

The way I describe works extremely well under conditions described earlier. (Please don't do it my way though, or you'll die).

It sounds like the way I described is like Tony's watch.

Tony, does it give you your average "rolling depth" as you're diving? Or only at the end on the surface?