Question Shearwater Teric (GF40/85) goes into DECO on first dive (max depth 25.9m, avg depth 17.6, duration 48mins)

[Sascha314]

That depends on the operator. For example, they are mandatory for Cayman Divers (LCBR and CBBR) and you even sign a waiver before diving that you will do them.

Well there is a difference between talking about a legal or medical requirement.

Its however a good advice to do this stop (even if well within NDL) at least if there is no other emergency thats more urgent. It gives some safety margin. There are studies that show the benefit, but its not taught by every agency. Its not totally clear to me if there are still these benefits if you dive with a conservative GF setting and maintain proper ascent rate.

 

[tursiops]

That depends on the operator. For example, they are mandatory for Cayman Divers (LCBR and CBBR) and you even sign a waiver before diving that you will do them.

Well there is a difference between talking about a legal or medical requirement.

Yes, but....
The PADI RDP -- which i believe was the first table that actually had safety stops on it -- "required" safety stops for all dives within 3 pressure-groups of rhe NDL, or for dives at 100 ft or greater. So, for example, a first clean dive to 80 ft on air has an NDL of 30 mins, but unless you ascend at 25 mins, you've got a required safety stop. That's equivalent to a SurfGF of less than ScubaDada's favored 95, which is what the 30 min NDL would give you.

 

[scubadada]

...That's equivalent to a SurfGF of less than ScubaDada's favored 95, which is what the 30 min NDL would give you.

Yes, I dive 80/95. I've used the SurfGF on my Teric since 2019 and have not surfaced with a GF greater than 80. Before that, I did an adaptive safety stop when close to the NDL on a no stop dive and padded my deco stop when in light deco

 

[rsingler]

Yes, I dive 80/95. I've used the SurfGF on my Teric since 2019 and have not surfaced with a GF greater than 80.

Probably minor quibble, but then why not dive 80/80? At least then you'll know how long you'll have to hang (you probably know already, from experience).

 

[Blackcrusader]

Probably minor quibble, but then why not dive 80/80? At least then you'll know how long you'll have to hang (you probably know already, from experience).

Perhaps we need a different thread to discuss what GF settings to use.
@Divedeeplastlong has perhaps not followed on. The dive he ignored his DC and his wife also seems to have missed her deco obligation just shows how people assume their DC's are wrong because they don't understand them. As a recreational diver I took the time to read the forums here on GF Surf GF and read the user manuals many times. Hopefully now this couple now learn to not ignore their DC's and just "follow" the guide.

 

[scubadada]

Probably minor quibble, but then why not dive 80/80? At least then you'll know how long you'll have to hang (you probably know already, from experience).

Good question.

I have been diving a computer running DSAT since 2002, 2,400 dives, and one of my computers is still running DSAT (a 2010 Oceanic VT3). I am very comfortable with this deco algorithm. I did not start diving Buhlmann until 2016 when I bought a Dive Rite Nitek Q, to learn this deco algorithm. The Nitek Q does not have SurfGF or GF99. I have had my Teric since 2019, about 660 dives, and have used SurfGF and GF99 since. For no stop dives, the more conservative of the two computers controls the dive. For light deco, I clear one or both computers. I use SurfGF to decrease my surfacing GF whenever that is necessary. I would rather spend more time on the bottom before having requisite deco time.

Diving a GF high of 95 allows a reasonably close match to DSAT. This combination allows me to know the maximum NDL I have before I would be willing to make a direct ascent to the surface, should that be necessary. It also tells me the minimum deco time to ascend safely from a light deco dive. I have never had to use either of these contingencies. I'm reasonably cautious in my diving, especially as I get older.

 

[dmaziuk]

Probably minor quibble, but then why not dive 80/80? At least then you'll know how long you'll have to hang (you probably know already, from experience).

If Craig is still doing no-stop dives with occasional "light deco" aka the boxes where optional stop is mandatory, then it should actually be 95/95. However in practice you have to set you GF Low to something really silly to make a practical difference: like 10.

At 80/95 his "light deco" should be no different from 95/95. At 80/80, OTOH, his NDL will be shorter.

 

[scubadada]

If Craig is still doing no-stop dives with occasional "light deco" aka the boxes where optional stop is mandatory, then it should actually be 95/95. However in practice you have to set you GF Low to something really silly to make a practical difference: like 10.

At 80/95 his "light deco" should be no different from 95/95. At 80/80, OTOH, his NDL will be shorter.

The GF low could give me a stop at 20 ft, it never has. Most of my light deco stops are <10 min, longest was 14 min.

 

[rsingler]

Though it's kindof beyond the scope of this forum, it sounds like what we're talking about is
A long "NDL dive" to 95, and then a safety stop until you offgas to 80, versus
A long "light deco dive", and then a deco stop until you offgas to 80.
The duration is the same. The nitrogen load is the same. The hang is the same. The semantics are different.

 

[scubadada]

Though it's kindof beyond the scope of this forum, it sounds like what we're talking about is
A long "NDL dive" to 95, and then a safety stop until you offgas to 80, versus
A long "light deco dive", and then a deco stop until you offgas to 80.
The duration is the same. The nitrogen load is the same. The hang is the same. The semantics are different.

Perhaps. I feel free to make a direct ascent to the surface below a GF high of 95 if need be. I'm not sure I would feel the same making a direct ascent to the surface in deco at a GF high of 80. I guess I should be able to figure that out with my SurfGF. We do what we are comfortable with and what has served us in the past.