Your Gradient Factors?

[scubadada]

Hi @100days-a-year

Thanks for your reply, I appreciate it. It was my impression that the Orcas were on the liberal side for repetitive dives. I still have a Cochran, it works, but haven't dived it for quite a while. It was 2-3 minutes more liberal on the 1st dive than than DSAT I showed in my previous post Your Gradient Factors? | Page 3 | ScubaBoard However, it became even a bit more relatively liberal on repetitive dives similar to how GF high of 95 does compared to DSAT.

Interesting stuff, I enjoy the history

 

[rjack321]

What, exactly, does average depth have to do with nitrogen uptake?

You seem awful angry at the concept of using average depth, which was a widespread practice in table diving before there were decent computers.

 

[tursiops]

You seem awful angry at the concept of using average depth, which was a widespread practice in table diving before there were decent computers.

I'm sorry, but I am unaware of any widespread use of average depth while using tables. All the tables I am aware of are based on maximum depth. Our "original" tables were from the Navy....no average depth used there. To what are you referring?

 

[scubadada]

I've never heard of using avg depth either, started using the USN tables in 1970.

@rjack321 how are avg depths used with tables?

 

[rjack321]

I've never heard of using avg depth either, started using the USN tables in 1970.

@rjack321 how are avg depths used with tables?

Back when we using computer based software to generate trimix tables - using average depth (within reason) was very widespread at least in the Puget Sound area. It's not like Hamilton based software/tables were ever validated anyway. 10 mins at 240 followed by 10mins at 220 on 15/55 ends up being a 20mins @ 230ft kind of dive. Also fairly common on long shallow air dives, Exley was averaging depth on long (2+ hr) cave dives in the 100ft range way back into the 1980s.

 

[scubadada]

Back when we using computer based software to generate trimix tables - using average depth (within reason) was very widespread at least in the Puget Sound area. It's not like Hamilton based software/tables were ever validated anyway. 10 mins at 240 followed by 10mins at 220 on 15/55 ends up being a 20mins @ 230ft kind of dive. Also fairly common on long shallow air dives, Exley was averaging depth on long (2+ hr) cave dives in the 100ft range way back into the 1980s.

Thanks for the reply, far above my pay grade

 

[tursiops]

LOL. So we've gone from "widespread use of average depth with tables" to some guys in the Puget sound area, based on Hamilton's tables for trimix, averaging 220 and 240 and getting 230. OK. And Exley averaging depth in caves. OK.

My skepticism remains. In general, tables are NOT designed for use with average depth, and those few who have decided to damn the torpedos and do so anyway are asking for trouble.

 

[Capt Jim Wyatt]

30/85

A good friend who is an MD, did a fellowship at Duke in hyperbaric medicine, USAF Flight Surgeon, NOAA DMO.....and more advised me to run 30/85 a few years ago, now I run 30/80 and often stay in the water until Surface GF% is 70.

Nothing beats having advice from the smartest dudes in the industry.

 

[_Ralph]

Seems to be 2 thoughts on average depth...

One is on planning your deco as rjack mentioned wrt tables and ratio deco.

And there is using the end of dive (descent, bottom phase and deco) average depth.

Which ever GF I use, I feel best when I exit the water when my total average depth is around 21m.....


If you change your GF, you change the shape of your deco. That can also affect your average depth for the total dive...

Similar in construct to ratio deco, it is a tool one can use to gauge, ‘have I done enough deco?’


_R

 

[michael-fisch]

LOL. So we've gone from "widespread use of average depth with tables" to some guys in the Puget sound area, based on Hamilton's tables for trimix, averaging 220 and 240 and getting 230. OK. And Exley averaging depth in caves. OK.

My skepticism remains. In general, tables are NOT designed for use with average depth, and those few who have decided to damn the torpedos and do so anyway are asking for trouble.

All right, as a recreational diver you drop to 130' for 1 minute at depth, ascend to 60' and stay at 60' for 45 minutes before slowly ascending to a safety stop at 15' for 5 minutes. When you surface will you immediatly die from DCS caused by your 46 minute 130' dive or do you have enough time to stow your gear, eat dinner and have a few beers before you die after having caused an accident while driving drunk?
That's a simple explanation of averaging depth during a dive. Average depths much greater than 60 or 70' end up causing a lot of pain and keep the chamber operators in business.

Michael